Smart Heater Controller

Minuscule circuit of the electronic heater controller presented here is built around the renowned 3-Pin Integrated Temperature Sensor LM35 (IC1) from NSC. Besides, a popular Bi Mos Op-amp CA3140 (IC2) is used to sense the status of the temperature sensor IC1, which also controls a solid-state switch formed by a high power Triac BT136(T1). Resistive type electric heater at the output of T1 turns to ON and to OFF states as instructed by the control circuit.

This gadget can be used as an efficient and safe heater in living rooms, incubators, heavy electric/electronic instrument etc. Normally, when the temperature is below a set value (Decided by multi-turn preset pot P1), voltage at the inverting input (pin2) of IC1 is lower than the level at the non-inverting terminal (pin3). So, the comparator output (at pin 6) of IC1 goes high and T1 is triggered to supply mains power to the desired heater element.

Electronic Heater Controller Circuit Schematic.

Note:

CA3140 (IC2) is highly sensitive to electrostatic discharge (ESD). Please follow proper IC Handling Procedures.

When the temperature increases above the set value, say 50-60 degree centigrade, the inverting pin of IC1 also goes above the non-inverting pin and hence the comparator output falls. This stops triggering of T1 preventing the mains supply from reaching the heater element. Fortunately, the threshold value is user-controllable and can be set anywhere between 0 to 100 Degree centigrade.

The circuit works off stable 9Volt dc supply, which may be derived from the mains supply using a standard ac mains adaptor (100mA at 9V) or using a traditional capacitive voltage divider assembly. You can find such power circuits elsewhere in this website.

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USB Power Booster

Power shortage problems arise when too many USB devices connected to PC are working simultaneously. All USB devices, such as scanners, modems, thermal printers, mice, USB hubs, external storage devices and other digital devices obtain their power from PC. Since a PC can only supply limited power to USB devices, external power may have to be added to keep all these power hungry devices happy. This circuit is designed to add more power to a USB cable line.

A sealed 12V 750 mA unregulated wall cube is cheap and safe. To convert 12 V to 5 V, two types of regulators, switching and linear are available with their own advantages and drawbacks. The switching regulator is more suitable to this circuit because of high efficiency and compactness and now most digital circuits are immune to voltage ripple developed during switching. The simple switcher type LM2575-5 is chosen to provide a stable 5V output voltage.

USB Power Booster Circuit Diagram

This switcher is so simple it just needs three components: an inductor, a capacitor and a high-speed or fast-recovery diode. Its principle is that internal power transistor switch on and off according to a feedback signal. This chopped or switched voltage is converted to DC with a small amount of ripple by D1, L1 and C2. The LM2575 has an ON/OFF pin that is switched on by pulling it to ground.

T1, R2, and R1 (pull-up resistor) pull the ON/OFF pin to ground when power signal from PC or +5 V is received. D2, a red LED with current resistor R3, serves to indicate ‘good’ power condition or stable 5V. C3 is a high-frequency decoupling capacitor. The author managed to cut a USB cable in half without actually cutting data wires. It is advisable to look at the USB cable pin assignment for safety.

Circuit Source: DIY Electronics Projects

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12v to 5v dc dc converter circuit diagram

Power supply is needed for all of electronic circuits. Say you have a 12V power supply and you want to use it as a 5V power supply. Then use this 12v to 5v dc-dc converter circuit diagram to convert 12 volt to 5 volt. This DC converter circuit provide 5V, 1Amp at output. Here is the small schematic circuit diagram of 12volt to 5volt converter.

Circuit Diagram of 12VDC to 5VDC converter:

Fig: 12 volt to 5 volt dc converter circuit schematic

This DC-DC converter is based on IC LM7805. The LM 7805 is a 3-terminal fixed output positive voltage regulator IC. The output current of this circuit is up to 1Amp . Use a heat sink with LM7805 to protect the IC from overheating.

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Simple L200 Charger

This circuit came about as the result of an  urgent need for a NiMH battery charger. No  suitable dedicated IC being immediately to  hand, the author pressed an L200 regulator and a 4.7 kΩ NTC thermistor into service.  Those components were enough to form the  basis of a charger with a cut-of f condition  based on cell temperature rise rather than  relying on the more common negative delta-V detection.

L200 Charger Circuit Diagram :

The circuit uses the L200 with the thermistor in the feedback loop. When ‘cold’ the  output volt age of the regulator is about 1.55 V per cell; when ‘warm’, at a cell temperature of about 35 °C to 40 °C, the out-put voltage is about 1.45 V per cell and the  thermistor has a resistance of about 3.3 kΩ.  This temperature sensing is enough to pre-vent the cells from being overcharged. P1  adjusts the charging voltage, and R2 limits  the charge current to 320 mA. The IC is fitted with a small 20 K/W heatsink as it dissipates around 1.2 watts in use.

The charger circuit can be connected permanently to the battery pa ck . Charging  starts when a ‘ wall wart ’ adaptor is connected to the input of the charger. The unregulated 12 V supply used by the author  delivered an open- circuit voltage of 18 V,  dropping to 14 V under load. Even though  the charge voltage is reduced when charging is complete, the cells should not be left  permanently on charge.

The author uses the circuit to charge the battery in a torch. After three years and some 150  charge cycles the cells are showing no signs of losing any capacity.

Link : http://www.ecircuitslab.com/2012/08/l200-charger-circuit.html

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Rocket

• One empty 35mm plastic film canister and lid. These are getting harder to find, but stores that develop film should have some. (The white canisters work much better than the black ones do.) If you have trouble finding canisters, you can get them HERE.
• One fizzing antacid tablet (such as Alka-Seltzer - Get this from your parents)
• Water
• Safety goggles

1. Put on those safety goggles and head outside - no really, when this works, that film canister really flies! If you want to try the indoor version, do not turn the canister upside down in step 5.

2. Break the antacid tablet in half.

3. Remove the lid from the film canister and put a teaspoon (5 ml) of water into the canister.

   Do the next 2 steps quickly 

4. Drop the tablet half into the canister and snap the cap onto the canister (make sure that it snaps on tightly.)

5. Quickly put the canister on the ground CAP SIDE DOWN and STEP BACK at least 2 meters.

6. About 10 seconds later, you will hear a POP! and the film canister will launch into the air!

Caution: If it does not launch, wait at least 30 second before examining the canister. Usually the cap is not on tight enough and the build up of gas leaked out.

Theres nothing like a little rocket science to add some excitement to the day. When you add the water it starts to dissolve the alka-seltzer tablet. This creates a gas call carbon dioxide. As the carbon dioxide is being released, it creates pressure inside the film canister. The more gas that is made, the more pressure builds up until the cap it blasted down and the rocket is blasted up. This system of thrust is how a real rocket works whether it is in outer space or here in the earths atmosphere. Of course, real rockets use rocket fuel. You can experiment controlling the rockets path by adding fins and a nose cone that you can make out of paper. If you like this experiment, try the Exploding Lunch Bag. Be safe and have fun!

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does water temperature affect how fast the rocket launches?
2. Does the size of the tablet piece affect how long it takes for the rocket to launch?
3. Can the flight path be controlled by adding fins or a nosecone to the canister?
4. How much water in the canister will give the highest flight?
5. How much water will give the quickest launch?

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‘Green’ Solar Lamp

Energy saving is all the rage, and here is our small contribution: how much (or rather how little) current do we need to light an LED? Experiments with a super-bright 1 W green LED showed that even one microamp was enough to get some visible light from the device. Rootling in the junk box produced a 0.47 F memory back-up capacitor with a maximum working voltage of 5.5 V. How long could this power the green LED? In other words, if discharged at one microamp, how long would the voltage take to drop by 1V?

A quick calculation gave the answer as 470 000 seconds, or about five days. Not too bad: if we use the capacitor for energy storage in a solar-powered lamp we can probably allow a couple more microamps of current and still have the lamp on throughout the night and day. All we need to add is a suitable solar panel. The figure shows the circuit diagram of our (in every sense) green solar lamp.


By Burkhard Kainka (Germany, Elektor)

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LED Workbench Lighting

Here is a very useful workbench lighting unit for electronics hobbyists. The portable inspection lamp circuit consists of an on-board voltage regulator and a high-bright 5mm white LED. Any 9 to 18 volt dc rated ac mains adaptor, capable to source about 100mA of output current can be used to power this portable inspection lamp.

After construction the led workbench light circuit should be enclosed in a suitable plastic bottle cap as illustrated here. The miniature lens shown is an optional component. In the prototype, plastic made lens lifted from a discarded torch was used!

LED workbench lighting lamp circuit schematic

The adjustable 3-pin voltage regulator IC1 (LM317L) in TO-92 pack, is here tuned to supply an output of near 4.5 volt dc. This supply is directly fed to the white LED (D2) through the current limiter resistor R3 (51 Ohm). Diode D1 (1N4001) works as an input polarity protection guard and two small electrolytic capacitors (C1 and C2) connected at the input and output pins of IC1 improves the overall stability of the regulator circuit. Use a standard RCA or EP socket as the input terminal J1.

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Basic single supply voltage regulator Circuit Diagram

The circuit uses a CA3140 BiMOS op amp capable of supplying a regulated output that can be adjusted from essentially 0 to 24 volts. The circuit is fully regulated.

 Basic single-supply voltage regulator Circuit Diagram

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Aviation Intercom Circuit

Before its move offshore, I was lucky enough to be involved in developing the avionics system for the Flightship Ground Effect FS8 craft (see www.pacificseaflight.com/craft.shtml). Although officially classed as a boat, it has wings and can travel at 180km/h some three metres above the water. The communications system was adapted from an aircraft unit and was a particular problem. It was expected to allow speech between the two pilots and radio, as well as receive audible warnings from the onboard computers and feed sound to the onboard data logger. Initially, the system was very noisy due to ground loops and incompatibility problems.

A circuit similar to that shown here was the solution. Although optimised to suit Softcom brand headphones with active noise reduction, it should be suitable for most aviation sets. The plugs indicated are standard aviation types but are insulated from the instrument panel to eliminate earth loops. The inputs from the two pilots microphones are summed and amplified by transistors Q1 & Q2. When one pilot presses his or her transmit key (mounted on the yoke), the transmit relay (RLY1) closes, muting the other pilot’s microphone via the optocoupler (OPTO1).

Aviation Intercom Circuit Diagram

The outputs from the microphone preamp, computer audio transformer (T1) and radio speaker transformer (T2) are summed via 10kΩ resistors and applied to the input of IC1, an LM386 audio amplifier. Note that transformers are used here to avoid creating additional earth loops. The output of the LM386 drives the pilots’ headphones via transformers T3 & T4, which are needed for impedance matching. Each audio source has its own level control (VR1, VR3 & VR4). The main volume control (VR5) is included to allow for ambient noise level. VR2 is used to set the signal level for the data logger.

Source: http://www.ecircuitslab.com/2011/06/aviation-intercom-circuit.html

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AUTOMATIC OFF TIMER FOR DVD PLAYERS

      Are you in the habit of falling asleep while listening to music? If yes, you’ll love this circuit. It will automatically start functioning when you switch off your bedroom light and shall turn your CD player ‘off’ after a predetermined time. In the presence of ambient light, or when you switch on light of the room in the morning, the CD player will again start playing. Unlike the usual timers, you don’t have to set this timer before sleeping.

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      The circuit derives its power directly from the bridge rectifiers. When ‘on’/‘off’ switch S1 is closed, LED1 glows to indicate that the circuit is powered ‘on.’

      In the presence of light, the resistance of the light-dependent resistor (LDR1) is low, so transistor T1 conducts to drive transistor T2 into cutoff state and the timer circuit remains inactive.

     The collector of transistor T2 is connected to reset pin 12 of IC CD4060 (IC1) via signal diode D5. IC CD4060 is a 14-stage ripple counter with a built-in oscillator. The time period of oscillations (t) is determined by capacitor C3 and resistor R8 connected to pins 9 and 10 of IC1, respectively, as

follows:

t=2.3RC

where ‘R’ is the value of resistor R8 and ‘C’ is the value of capacitor C3.

     When transistor T2 is cut-off, its collector voltage is high. So pin 12 of IC1 is high and IC1 is in reset condition.

     When light is switched off, the resistance of LDR1 increases, driving transistor T1 into cut-off state. The collector voltage of transistor T1 goes high to light up LED2 (indicating that the timer circuit is enabled) and transistor T2 starts conducting. As the collector voltage of transistor T2 goes low to around 0.2V, ground potential becomes available at reset pin 12 of IC1. The low state at pin 12 enables the oscillator and it starts counting. LED3 at pin 7 of IC1 starts blinking. Its blinking frequency depends on the R-C components connected between its pins 9 and 10.

     The status of LED2 and LED3 in the circuit with light falling and not falling on LDR1 is given below:

LDR1	Timer LED2	Reset pin 12	Count LED3
Light	Off	High	Off
Dark	On	Low	Blink

     During counting, in case the power fails momentarily, capacitor C2 (1000μF) will provide the necessary power backup for IC1. That is, during the period, pin 3 of IC1 is low. When output pin 3 of IC1 goes high, the relay is energised through transistors T3 and T4 and, at the same time, counting is disabled by the feedback from pins 3 through 11 (clock input) of IC1 via signal diode D7. That is, due to the feedback, output pin 3 remains high unless another high-to-low pulse is received at its reset pin 12.

     After the relay is energised, there will be no AC power in the socket. The glowing of LED5 indicates that your CD player has been switched off.

     The desired ‘off’ time period for the timer circuit can be set by choosing proper values of resistor R8 and capacitor C3. If R8 is 680 kilo-ohms and C3 is 0.22 μF, the ‘off’ time period is around 45 minutes.

     The glowing of LED4 gives the warning that your CD player is going to be switched off shortly. In case you want to extend the timer setting for another round, just press reset switch S2 momentarily. LED4 stops glowing and counting starts again from the initial stage.

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Build a Period To Voltage Converter Circuit Diagram

The input signal drives ICD. Because ICD`s positive input (V+) is slightly offset to + 0.1 V, its steady stateoutput will be around +13 V. This voltage is sent to ICC through D2, setting ICC`s output to +13 V. Therefore, point D is cut off by Dl, and CI is charged by the current source. Assuming the initial voltage on CI is zero, the maximum voltage (^Cinax) is given by: 

When the input goes from low to high, a narrow positive pulse is generated at point A. This pulse becomes -13 V at point B, which cuts off D2. ICC`s V+ voltage becomes zero. The charge on CI will be absorbed by ICC on in a short time. 

The time constant of C2 and R5 determines the discharge period— about 10 /is. ICB is a buffer whose gain is equal to (R& + R9)~Rg = lM5. ICD`s average voltage will be (1362f 1.545) + 2 = 1052/. RIO and C3 smooth the sawtooth waveform to a dc output.

Period-To-Voltage Converter Circuit Diagram

Build a Period-To-Voltage Converter Circuit Diagram

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EL Lamp Driver Using HV832MG

An EL lamp is a solid state, low power, uniform area light source. Because of its thin profile (as thin as 0.3 mm) and the fact that it can be built into almost any size and shape, EL lamps are an ideal way to provide back-lighting for LCD displays, membrane keypads and a variety of other applications. Electroluminescent (EL) lamps offer significant advantages over point light sources such as LEDs, incandescent, and fluorescent lighting systems. As a result of these advantages, EL lamps are seeing growing use. Many wireless phone and pager manufacturers are converting to EL lighting systems in keypads and displays. The typical lamp consists of light emitting phosphor sandwiched between two conductive electrodes with one of the electrodes transparent so allowing light to escape.

As an AC voltage is applied to the electrodes, the electrical field causes the phosphor to rapidly charge and discharge, resulting in the emission of light during each cycle. Since the number of light pulses depends on the magnitude of the applied voltage, the brightness of EL lamps can generally be controlled by varying the operating voltage. Because EL lamps are a laminate, they exhibit a capacitance of the order of 2.5 nF to 3.5 nF per square inch. When high voltage is applied across the electrodes, the resulting electric field excites the phosphor atoms to a higher energy state.

When the electric field is removed, the atoms fall back to a lower energy state, emitting photons in the process. The wavelength of the emitted light is determined by the type of phosphor used and the frequency of the excitation voltage. With most phosphors, the spectrum of emitted light will tend to shift towards blue with an increase in excitation frequency. Color is usually controlled, however, by selecting the phosphor type, by adding fluorescent dyes in the phosphor layer, through the use of a color filter over the lamp, or a combination of these. EL lamp brightness increases approximately with the square of applied voltage. Increasing frequency, in addition to affecting hue, will also increase lamp brightness, but with a nearly linear relationship.


Most lamp manufacturers publish graphs depicting these relationships for various types of lamps. Excitation voltages usually range from 60 VPP to 200 VPP at 60 Hz to 1 kHz. Increased voltage and/or frequency, however, adversely affects lamp life, with higher frequencies generally decreasing lamp life more than increased voltage. EL lamps, unlike other types of light sources, do not fail abruptly. Instead, their brightness gradually decreases through use. For intermittent use, lamp life is seldom a concern. For example, if a lamp is used 20 minutes per day, over the course of 10 years the lamp will be activated for a total of 1,216 hours, well within the useful life of almost any EL lamp available.

When designing a drive circuit, a balance needs to be struck between lamp brightness, hue, useful life, and supply current consumption. To generate the high voltages needed for driving EL lamps, dedicated ICs like the Supertex HV832MG employ switch-mode converters using inductive flyback. By integrating high voltage transistors on-chip, this driver avoids the need for expensive, bulky, and noisy transformers to generate high output voltages. The HV832MG employs open-loop conversion. This EL driver incorporates a lamp drive oscillator that is separate from the power conversion oscillator. This allows setting lamp drive frequency independently from the power conversion frequency and so optimize overall performance.

The power conversion cycle begins when a MOSFET switch in the HV832MG is turned on and current begins to rise in inductor Lx. When the switch is turned off, inductive flyback causes the voltage across the inductor to reverse polarity and rise until it reaches the level of the storage capacitor CS, (plus diode drop) at which point the rectifier conducts and the energy contained in the magnetic field of the inductor is transferred to CS. When all the inductor energy is transferred and inductor current drops to zero, the rectifier stops conducting and inductor voltage drops to zero, ready for the next cycle. Output power is simply the amount of energy transferred per cycle multiplied by the number of cycles per second.

It is important to select the inductor and conversion frequency to provide the required output voltage while assuring that the inductor current does not approach saturation levels. If the inductor saturates, excessive current will flow, potentially leading to device failure. Ideally, the inductor current should be allowed to return to zero between cycles. If inductor current is not allowed to return to zero, a higher average current will be needed to meet output power requirements, increasing I2R losses, and decreasing conversion efficiency. On he other hand, if too much time is allowed between zero inductor current and the start of the next cycle, more energy will need to be transferred each cycle to maintain output power, thus risking inductor saturation and increasing I2R and core losses.

This circuit provides an output of 130 volts at 300-450 Hz, draws just 30mA current, yet is capable of driving EL lamps with a surface area of up to 9 cm2. This design has excellent drive capability and provides a symmetrical bipolar drive, resulting in a zero-bias signal. Many lamp manufacturers recommend a zero-bias drive signal to avoid potential migration problems and increase lamp life. The supply voltage should be bypassed with a capacitor located close to the lamp driver. Values can range from 0.1µF to 1µF depending on supply impedance. For very large lamps representing much larger capacitances, a FET follower circuit may be employed to boost the output drive capability of the lamp driver. The HV832MG may be obtained from Supertex Semiconductors, USA, www.supertex.com.

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Fuse Box BMW 1984 528I Diagram

Fuse Box BMW 1984 528I Diagram - Here are new post for Fuse Box BMW 1984 528I Diagram.

Fuse Box BMW 1984 528I Diagram

Fuse Panel Layout Diagram Parts: low beam relay, fog light relay, main relay, purge valve relay, normal speed relay, high speed relay, low beam check relay, high beam relay, fuel pump relay, horn relay, wiper control unit, unloader relay.

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IR–S PDIF Transmitter

The best-known ways to transmit a digital audio signal (S/PDIF) are to use a standard 75Ω coaxial cable or Toslink optical modules with matching optical cable. Naturally, it can happen that for whatever reason, you cannot (or don’t wish to) run a cable between the equipment items in question. With a wireless solution, you have the choice of a wideband RF transmitter or an optical variant. Here we describe a simple optical transmitter. The matching IR-S/PDIF receiver is described else-where in this website. Although designing such an IR transmitter/receiver system does not have to be particularly difficult, in practice there are still several obstacles to be overcome. For one thing, the LEDs must have sufficient optical switching speed to properly pass the high frequencies of the S/PDIF signal, and they must also produce sufficient light intensity to deliver a noise-free signal at the receiver over a reasonable distance.

At a sampling frequency of 48 kHz, it’s necessary to be able to transfer pulses only 163 ns wide! The LEDs selected here (Agilent HSDL-4230) have optical rise and fall times of 40ns, which proved to be fast enough in practice. With a beam angle of only 17°, they can also provide high light intensity. The downside is that the combination of transmitter and receiver is highly directional, but the small beam angle also has its advantages. It means that fewer LEDs are necessary, and there is less risk of continuously looking into an intense infrared source. The circuit is essentially built according to a standard design. The S/PDIF signal received on K1 is amplified by IC1a to a level that is adequate for further use. JP1 allows you to use a Toslink module as the signal source if desired. JP1 is followed by a voltage divider, which biases IC1b at just below half of the supply voltage.

This causes the output level of the buffer stage driving switching transistor T1 to be low in the absence of a signal, which in turn causes IR LEDs D1 and D2 to remain off. The buffer stage is formed by the remaining gates of IC1. This has primarily been done with an eye to elevated capacitive loading, in the unlikely event that you decide to use more LEDs. A small DMOS transistor (BS170) is used for T1; it is highly suitable for fast switching applications. Its maximum switching time is only 10 ns (typically 4 ns). Getting D1 and D2 to conduct is not a problem. However, stopping D1 and D2 from conducting requires a small addition to what is otherwise a rather standard IR transmitter stage, due to the presence of parasitic capacitances.

This consists of R7 and R8, which are connected in parallel with the LEDs to quickly discharge the parasitic capacitors. The drawback of this addition is naturally that it somewhat increases the current consumption, but with the prototype this proved to be only around 10 percent. With no signal, the circuit consumes only 25 mA. With a signal, the output stage is responsible for nearly all of the current consumption, which rises to approximately 170 mA. In order to prevent possible interference at such high currents and avoid degrading the signal handling of the input stage, everything must be well decoupled. For instance, the combination of L2, C4 and C5 is used to decouple IC1.

The circuit around T1 must be kept as compact as possible and placed as close as possible to the voltage regulator, in order to prevent the generation of external interference or input interference. If necessary, place a noise-suppression choke (with a decoupling capacitor to ground) in series with R9. Note that this choke must be able to handle 0.3 A, and if you use additional stages, this rating must be increased proportionally. The circuit should preferably be fitted into a well-screened enclosure, and it is recommended to provide a mains filter for the 230-V input of the power supply. For the sake of completeness, we have included a standard power supply in the schematic diagram, but any other stabilized 5-V supply could be used as well. LED D3 serves as the obligatory mains power indicator.

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Push Off Push On

The ubiquitous 555 has yet another airing with this bistable using a simple push-button to provide a push-on, push-off action. It uses the same principle of the stored charge in a capacitor taking a Schmitt trigger through its dead-band. Whereas the Schmitt trigger in that reference was made from discrete components, the in-built dead-band arising from the two comparators, resistor chain and bistable within the 555 is used instead. The circuit demonstrates a stand-by switch, the state of which is indicated by illumination of either an orange or red LED, exclusively driven by the bipolar output of pin 3. Open-collector output (pin 7) pulls-in a 100mA relay to drive the application circuit; obviously if an ON status LED is provided elsewhere, then the relay, two LEDs and two resistors can be omitted, with pin 3 being used to drive the application circuit, either directly or via a transistor.

The original NE555 (non-CMOS) can source or sink 200mA from / into pin 3. Component values are not critical; the ‘dead-band’ at input pins 2 and 6 is between 1/3 and 2/3 of the supply voltage. When the pushbutton is open-circuit, the input is clamped within this zone (at half the supply voltage) by two equal-value resistors, Rb. To prevent the circuit powering-up into an unknown condition, a power-up reset may be applied with a resistor from supply to pin 4 and capacitor to ground. A capacitor and high-value resistor (Rt) provide a memory of the output state just prior to pushing the button and creates a dead time, during which button contact bounce will not cause any further change. When the button is pressed, the stored charge is sufficient to flip the output to the opposite state before the charge is dissipated and clamped back into the neutral zone by resistors Rb. A minimum of 0.1 µF will work, but it is safer to allow for button contact-bounce or hand tremble; 10 µF with 220 k gives approximately a 2-second response.

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Simple Infrared Remote Control Extender

This ultra-simple remote control extender is ideal for use with a hidden video recorder. The recorder is a Panasonic NV-SD200 and is used as part of a camera surveillance system. A PICAXE-08-based circuit is used to detect events and control the recorder. It also flashes a LED near the monitor to indicate the number of events since last viewing.
Click for larger image

Strangely, the NV-SD200 model refused to work with a number of commercial infrared remote control extenders, hence the need for this design. As a bonus, it uses less power than a traditional extender (no plugpacks) and the remote can still be used in the normal manner.

As shown, an additional 5mm infrared LED is mounted directly in front of the equipment to be controlled. This is cabled back to a convenient location near the monitor and terminated in a 3.5mm plug.

To modify the remote control unit, break the circuit to the anode of the existing infrared LED and wire in a 3.5mm headphone socket. In most cases, the LED will be accessible without dismantling the circuit board. The purpose of the socket is to allow the existing infrared LED to operate normally when the jack is unplugged.

If the socket won’t fit inside the case, then a very short flying lead with a moulded in-line socket can be used instead. By using light-duty figure-eight cable, the transmitting LED could be 30m or more from the hand-held remote control without problems.

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Dimmer Control Voltage Polarity Changer Circuit

Some older Strand dimmer units used a zero to -10V control signal, and the standard analogue control voltage is zero to +10V. This project allows the easy conversion from one standard to another. This is a very simple project, but may turn out to be a lifesaver for small theatre groups and the like. It has come to my attention that there are still a great many old Strand dimmers very much in use. The problem is that they are just too reliable, and wont go away ... but, they use a zero to -10V control signal, so are incompatible with the dimmer unit in these project pages, and with any new commercial analogue control console.

In addition, there are no doubt quite a few old lighting consoles that use this standard, which means that they cant drive modern dimmer packs. As it turns out, a simple opamp inverter will convert either standard to the other. This is shown in Figure 1.

 Figure 1 - Dimmer Control Signal Inverter

There is really nothing to it. Use as many circuits as needed, and a simple power supply (such as that in Project 05) will drive as many of these inverters as are likely to be required in any lighting setup. The above circuit has two channels, and may be simply repeated as many times as you need to get the required number of channels. The 100 ohm resistors on each output are there to prevent the opamps from oscillating when supplying a capacitive load (such as a coax cable).
With an input of zero volts, the output will also be at zero volts. As the input increases (or decreases in the case of the -10V control) the output will change by exactly the same value, but in the opposite direction. Wiring is not critical, the 1458 opamps specified are very cheap (but more than capable of doing the job), and they can be built very simply on Veroboard or similar. Supplies should be bypassed to common (ground) with 10uF electrolytic caps.

source: http://sound.westhost.com/project90.htm

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Two Wire Temperature Sensor

The Type LM35 temperature sensor from National Semiconductor is very popular for two reasons: it produces an output voltage that is directly proportional to the measured temperature in degrees Celsius, and it enables temperatures below zero to be measured. A drawback of the device is, however, that in its standard application circuit it needs to be connected to the actual measuring circuit via a three-wire link. This drawback is neatly negated by the present circuit. When the LM35 is connected as shown, a two-wire link for the measurement range of –5 °C to +40 °C becomes possible.

Actually, the circuit shown is a temperature-dependent current source, since it uses the variation of the quiescent current with changes in temperature. The values of resistors R3 and R4 are calculated to give an output voltage of 10mV °C–1. Where good accuracy is desirable or necessary, 1% resistors should be used. In this context, note that a loss resistance in the link between sensor and measuring circuit may cause a measurement error of about 1 °C for every 5 ohms of resistance. Capacitor C1 eliminates undesired interference and noise signals. At an ambient temperature of 25 °C, the circuit draws a current of about 2mA.

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Cable Tester Uses Quad Latch

This circuit was designed to allow microphone cables or other cables to be easily tested for intermittent breaks that can often be difficult to find using a multimeter. The circuit can test cables with up to four cores. Both switches used in the circuit are momentary contact push-buttons and it can run from a 9V battery, in which case the 7805 regulator can be omitted. To test a cable, connect it between the two sockets and press switch S2 which resets all four latches in IC1, setting them low. This turns on all four LEDs.

A good connection for each core of the cable will mean that the relevant Set inputs of the latches (pins 3, 7, 11 & 15) will be pulled high and the appropriate LED will remain on. A broken connection in the cable will result in the relevant Set input being pulled low by the associated 10kΩ resistor and the so the LED will be off. Because the circuit latches, it is easy to pinpoint even the smallest breaks by simply flexing and twisting the cable up and down its length until one of the LEDs turns off. To test different types of cables, simply connect appropriate sockets in parallel with or in place of the XLR sockets.

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Mini Guitar Bass Amplifier

Output power: 6W into 4 Ohm load, FET input stage - Passive Tone Control

Tiny, portable Guitar Amplifiers are useful for practice on the go and in bedroom/living room environment. Usually, they can be battery powered and feature a headphone output. This project is formed by an FET input circuitry, featuring a High/Low sensitivity switch, followed by a passive Tone Control circuit suitable to Guitar or Bass. After the Volume control, a 6W IC power amplifier follows, powered by a 12-14V dc external supply Adaptor or from batteries, and driving a 4 Ohm 10 or 13cm (4"/5") diameter car loudspeaker. Private listening by means of headphones is also possible.

Parts:

P1______________1M Linear Potentiometer
P2____________100K Log Potentiometer
R1_____________68K 1/4W Resistor
R2____________470K 1/4W Resistor
R3______________2K7 1/4W Resistor
R4______________8K2 1/4W Resistor
R5____________680R 1/4W Resistor
R6____________220K 1/4W Resistor
R7_____________39R 1/4W Resistor
R8______________2R2 1/4W Resistor
R9____________220R 1/4W Resistor
R10_____________1R 1/4W Resistor
R11___________100R 1/2W Resistor
R12_____________1K5 1/4W Resistor
C1____________100pF 63V Polystyrene or Ceramic Capacitor
C2,C5,C9,C14__100nF 63V Polyester Capacitors
C3____________100µF 25V Electrolytic Capacitor
C4_____________47µF 25V Electrolytic Capacitor
C6______________4n7 63V Polyester Capacitor
C7____________470pF 63V Polystyrene or Ceramic Capacitor
C8______________2µ2 25V Electrolytic Capacitor
C10___________470µF 25V Electrolytic Capacitor
C11____________22nF 63V Polyester Capacitor
C12__________2200µF 25V Electrolytic Capacitor
C13__________1000µF 25V Electrolytic Capacitor
D1______________3mm red LED
Q1____________BF245 or 2N3819 General-purpose N-Channel FET
IC1_________TDA2003 10W Car Radio Audio Amplifier IC
SW1,SW2________SPST toggle or slide Switches
J1____________6.3mm Mono Jack socket
J2____________6.3mm Stereo Jack socket (switched)
J3_____________Mini DC Power Socket
SPKR__________4 Ohm Car Loudspeaker 100 or 130mm diameter

Notes:

• Connect the output Plug of a 12 - 14V dc 500mA Power Supply Adaptor to J3
• Please note that if the voltage supply will exceed 18V dc the IC will shut down automatically

Technical data:

Output power (1KHz sinewave):
6W RMS into 4 Ohm at 14.4V supply
Sensitivity:
50mV RMS input for full output
Frequency response:
25Hz to 20kHz -3dB with the cursor of P1 in center position
Total harmonic distortion:
0.05 - 4.5W RMS: 0.15% 6W RMS: 10%

Tone Control Frequency Response:

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1kH Synthetic Inductor

Inductors can be mimicked quite easily using operational amplifiers. The circuit shown here was developed to have an inductance of 1000 H (say, one thousand Henry) with good damping. Using this design you can build a resonant circuit with a center frequency of less than 1 Hz. The slow behavior allows you to use conventional measuring instruments to investigate the circuit in real time. The circuit can also be used as part of a filter design. Opamp1 operates as an Integrator, Opamp2 as a difference amplifier.

The output voltage of Opamp2 is equal to the voltage drop across R1 and P1, which is proportional to the output current. This voltage is differentiated by Opamp1, C1 and R2. The net effect is that the circuit behaves as an inductor. P1 allows adjustment of the inductance value. P2 allows adjustment of the Q factor of the coil by altering the symmetry of the difference amplifier and with it the stability of the circuit.

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An Accurate Reaction Timer Circuit

Add a cheap stopwatch to this circuit to produce an accurate reaction timer. The circuit is wired in parallel with the start/stop button in the watch via a 2.5mm socket, which fits snugly in one corner of the casing. The person conducting the test (the "tester") resets the stopwatch and turns on the reaction timer’s power switch (S3).

The person being tested (the "subject") places his or her fingers near the "STOP" push-button switch (S4). Next, the tester covertly sets a delay time with VR1 and selects either the LED or buzzer alarm via S2. To initiate the sequence, the tester then presses the "START" switch (S1). This triggers 555 timer IC1, which is wired as a monostable. Its output (pin 3) goes high for 2-12 seconds as determined by the setting of VR1. At the end of this delay pin 3 goes low and triggers IC2, another 555 timer in monostable mode.

Circuit diagram:

 An Accurate Reaction Timer Circuit Diagram

The output from IC2 (pin 3) activates the alarm (buzzer or LED) for about 0.5s. After inversion by Q1, it also triggers IC3, another 555 monostable. The positive pulse from IC3 turns on Q2, briefly closing the start/stop switch circuit in the watch. The watch starts to count up. After a short period, the subject reacts to the alarm and pushes the "STOP" button (S4), freezing the stopwatch. The reaction time can then be read off with 1/100th of a second accuracy.

Comparative reaction times could be measured when a subject is: rested or tired, silent or talking, before or after a night out, using a mobile phone, etc. For motoring realism, rig up dummy accelerator and brake pedals, with the brake switch making the stop contact. Or take it to your club and test people as they enter and after they’ve been "steadying their nerves" at the bar.

Author: A. J. Lowe - Copyright: Silicon Chip Electronics

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Telephone Ringer Circuit

If you are lucky enough to have a big house, a large garden, and small children, this project just might interest you. It’s actually a telephone ringer capable of making any mains-powered device work from the ringer of your fixed line. With it, you will be able to control a high-powered siren or horn, as you like, in order to relay and amplify the low-level sound of your telephone (making it audible in a big house or in a large garden)! Alternatively, you can make a lamp light (or an indicator light) and so create a ‘silent ringer’ (helpful when small children are napping).

The other interesting part of this simple and inexpensive project is that it doesn’t require a power supply, contrary to similar items on sales in the shops. Before examining the drawing and understanding the principle involved, it is important to know that the ringer voltage on a fixed telephone line is pretty high. Since Europe and the EU Commission have not yet interfered, the exact value of this voltage and its frequency varies according to the country, but that’s not important here. The line carries direct current whether unoccupied or occupied.

Moreover, no more than a few hundred mAs needs to be stolen from an unoccupied telephone line to make the PSTN exchange believe the line is occupied. Therefore, capacitor C1 has the dual role of insulating this project with respect to direct current present on the line while unoccupied, or while occupied, while also allowing the ringer current to pass. The latter is rectified by D1 and clipped by D2 which makes about 6 V DC available to the C2 terminals when a ringer signal is present.

Circuit Diagram :

 Telephone Ringer Circuit Diagram

This voltage lights LED D3 which only serves as a visual indicator of proper operation as does the LED contained in IC1. This is a high-power photo triac with zero crossing detection from the mains, which allows it to switch the load it controls without generating even the lowest level of noise. This component, that we might just as well call a solid-state relay, was selected because it is comes in the form of a package similar to a TO220, a little bigger, and equipped with four pins. The pinout will not cause confusion because the symbols shown on our diagram are engraved or printed on the packaging. Since this circuit is not yet very common, we need to mention that it’s available from the Conrad Electronics website (www1.uk.conrad.com).

For the purpose of safe operation, the circuit is protected by a GeMOV on the mains side, called Varistor, VDR or SiOV depending on the manufacturer. The model indicated here is generally available. The load will be limited to 2 A, considering the model selected for IC1, which is more than sufficient for the application planned here. Finally, since a number of components in this circuit are connected directly to the mains power supply, the assembly should be placed in a completely insulated housing for obvious safety reasons.

Author: Christian Tavernier - Copyright: Elektor Electronics Magazine

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Voice Bandwidth Filter

This circuit passes frequencies in the 300Hz - 3.1kHz range, as present in human speech. The circuit consists of cascaded high-pass and low-pass filters, which together form a complete band-pass filter. One half of a TL072 dual op amp (IC1a) together with two capacitors and two resistors make up a second-order Sallen-Key high-pass filter. With the values shown, the cut-off frequency (3dB point) is around 300Hz. As the op amp is powered from a single supply rail, two 10kO resistors and a 10µF decoupling capacitor are used to bias the input (pin 5) to one-half supply rail voltage.

The output of IC1a is fed into the second half of the op amp (IC1b), also configured as a Sallen-Key filter. However, this time a low-pass function is performed, with a cut-off frequency of about 3.1kHz. The filter component values were chosen for Butterworth response characteristics, providing maximum pass-band flatness. Overall voltage gain in the pass-band is unity (0dB), with maximum input signal level before clipping being approximately 3.5V RMS. The 560O resistor at IC1bs output provides short-circuit protection.

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Fire Alarm Using Thermistor

Small and simple unit, Can be used for Home-Security purpose

In this fire alarm circuit, a Thermistor works as the heat sensor. When temperature increases, its resistance decreases, and vice versa. At normal temperature, the resistance of the Thermistor (TH1) is approximately 10 kilo-ohms, which reduces to a few ohms as the temperature increases beyond 100 C. The circuit uses readily available components and can be easily constructed on any general-purpose PCB.

Circuit Diagram:

Fire Alarm Using Thermistor Circuit Diagram

Parts	Description
R1	470R
R2	470R
R3	33K
R4	560R
R5	470R
R6	47K
R7	2.2K
R8	470R
C1	10uF-16V
C2	0.04uF-63V
C3	0.01uF-63V
Q1	BC548
Q2	BC558
Q3	SL100B
D1	Red Led
D2	1N4001
IC1	NE555
SPKR	1W-8R
TH1	Thermistor-10K

Circuit Operation:

Timer IC NE555 (IC1) is wired as an astable multivibrator oscillating in audio frequency band. Switching transistors Q1 and Q2 drive multivibrator IC1. The output of IC1 is connected to NPN transistor Q3, which drives the loudspeaker (SPKR) to generate sound. The frequency of IC1 depends on the values of resistors R6, R7 and capacitor C2. When Thermistor TH1 becomes hot, it provides a low-resistance path to extend positive voltage to the base of transistor Q1 via diode D2 and resistor R3. Capacitor C1 charges up to the positive voltage and increases the ‘on’ time of alarm. The higher the value of capacitor C1, the higher the forward voltage applied to the base of transistor Q1. Since the collector of transistor Q1 is connected to the base of transistor Q2, transistor Q2 provides positive voltage to reset pin 4 of IC1. R5 is used such that IC1 remains inactive in the absence of positive voltage. D2 stops discharging of capacitor C1 when the Thermistor connected to the positive supply cools down and provides a high-resistance (10k) path. It also stops the conduction of Q1. To prevent the Thermistor from melting, wrap it up in mica tape. The circuit works off a 6V-12V regulated power supply. D1 is used to indicate that power to the circuit is switched on.

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Supply Voltage Indicator

A novel supply voltage monitor which uses a LED to show the status of a power supply.

This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device): as long as the indicator has good 12 volts at its input, LED1 gives steady, uninterrupted (for the naked eye) yellow light. If the input voltage falls below 11 V, LED1 will start to blink and the blinking will just get slower and slower if the voltage drops further - giving very clear and intuitive representation of the supplys status. The blinking will stop and LED1 will finally go out at a little below 9 volts. On the other hand, if the input voltage rises to 13 V, LED2 will start to glow, getting at almost full power at 14 V. The characteristic voltages can be adjusted primarily by adjusting the values of R1 and R4. The base-emitter diode of T2 basically just stands in for a zener diode.

The emitter-collector path of T1 is inversely polarized and if the input voltage is high enough - T1 will cause oscillations and the frequency will be proportional to the input voltage. The relaxation oscillator ceases cycling when the input voltage gets so low that it no longer can cause breakdown along the emitter-collector path. Not all small NPN transistors show this kind of behavior when inversely polarized in a similar manner, but many do. BC337-40 can start oscillations at a relatively low voltage, other types generally require a volt or two more. If experimenting, be careful not to punch a hole through the device under test: they oscillate at 9-12 V or not at all.

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ECG Amplifier By TLC274

This circuit allows an ECG signal to be displayed on an oscilloscope. Opamps IC1a, b and d form an instrumentation amplifier with a gain of 201. IC1c amplifies the common-mode signal by a factor of 31, and supplies this signal to the right leg. The first consequence of this is that the body is brought to a defined common-mode level, so that the signal will not lie outside the range of the instrumentation amplifier.

The second consequence is that negative feedback is applied to the common-mode signal, so that the amplitude of this (undesired) signal is reduced even further. Diodes D1 through D4, along with resistors R1 and R5, are added to the circuit to protect the inputs against damage from excessive electrostatic charges. The CMRR (common-mode rejection ratio) of the instrumentation amplifier can be set using P1.

To make this adjustment, connect both inputs of the instrumentation amplifier together, and then connect a 100mV, 50Hz AC signal between the connected inputs and earth. Measure the output signal using an oscilloscope, and adjust P1 to minimize the level of the output signal. It is important that the electrodes make very good contact with the skin. In our test measurements, winding three uninsulated copper wires several times around the index fingers (and the right leg) proved to be sufficient to provide a good signal.

The amplitude of the ECG signal measured with this arrangement was 200mV. The current consumption of this circuit is only 2mA, so the batteries should last a long time. This circuit must never be connected to a mains-operated power supply, in consideration of safety precautions that are necessary when making this sort of measurement on the human body.

Source : www.extremecircuits.net

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Tuned Radio Frequency TRF Receiver

Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver technologies such as the TRF receiver and the regenerative receiver were still widespread. The circuit described here is based on the old technology, but brought up-to-date a The most important part of the circuit is the input stage, where positive feedback is used to achieve good sensitivity and selectivity. The first stage is adjusted so that it is not quite at the point of oscillation. This increases the gain and the selectivity, giving a narrow bandwidth.

To achieve this, the potentiometer connected to the drain of the FET must be adjusted very carefully: optimal performance of the receiver depends on its setting. In ideal conditions several strong stations should be obtainable during the day using a 50 cm antenna. At night, several times this number should be obtainable. The frequency range of the receiver runs from 6 MHz to 8 MHz. This range covers the 49 m and the 41 m shortwave bands in which many European stations broadcast. Not bad for such a simple circuit! The circuit employs six transistors. The first stage is a selective amplifier, followed by a transistor detector. Two low-frequency amplifier stages complete the circuit.

The final stage is a push-pull arrangement for optimal drive of the low-impedance loudspeaker. This circuit arrangement is sometimes called a ‘1V2 receiver’ (one preamplifier, one detector and two audio-frequency stages). Setting-up is straightforward. Adjust P1 until the point is reached where the circuit starts to oscillate: a whistle will be heard from the loudspeaker. Now back off the potentiometer until the whistle stops. The receiver can now be tuned to a broadcaster. Occasional further adjustment of the potentiometer may be required after the station is tuned in. The receiver operates from a supply voltage of between 5 V and 12 V and uses very little current. A 9 V PP3 (6F22) battery should give a very long life.

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Laser Alarm

This circuit is a laser alarm system like the one we see in various movies. It uses a laser pointer beam to secure your valuables and property. Essentially, when the beam gets interrupted by a person, animal or object, the resistance of a photodiode will increase and an alarm will be activated. The laser and the receiver can be fitted in same box, sharing a common power supply. As the receiver draws less than 10 mA on average, you’ll soon find that the laser is the most current hungry device! Mirrors are used to direct the beam in whatever setup you require. Examples of a passage and an area protected by the alarm are shown in the diagram.

In the circuit diagram we find a TL072 op-amp (IC1.A) configured as voltage comparator between the voltage reference provided by the adjustable voltage divider P1/R4 and the light-dependent voltage provided by the voltage divider consisting of photodiode D1 and fixed resistor R3. When the laser beam is interrupted, the voltage on comparator pin 2 drops below that at pin 3, causing the output to swing to (almost) the positive supply voltage and indicating an alarm condition. This signal can drive a siren, a computer or a light that hopefully will deter the intruder.

Alternatively it can be used to ‘silently’ trigger a more sophisticated alarm. Resistor R2 provides some hysteresis to prevent oscillation when the two comparator input voltages are almost equal. Capacitor C1 makes the circuit immune to short, accidental interruptions of the beam, e.g., by flying insects. If you want your circuit to have faster responses you can reduce its value to 1 µF. The operation of the circuit is illustrated by the waveform diagram, which also proves the hysteresis action that sets an upper and a lower threshold on the input voltage. You can also see the delay introduced by capacitor C1.

The circuit is simple and could be assembled on a piece of breadboard. After assembling the circuit and testing it, you should mount it in a black box that has just a small hole. You may decide to put the laser in the same box but only if you are sure there is no way the photodiode can ‘see’ the laser beam directly. The small hole should be filled with a black drinking straw so that only light from the direction of the laser beam can enter. With the appropriate setup of the box and the mirrors, the laser beam is so intense that even direct sunlight cannot affect the operation of the photodiode.

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1W LED Driver Circuit

This circuit is designed to drive the 1W LEDs that are now commonly available. Their non-linear voltage to current relationship and variation in forward voltage with temperature necessitates the use of a 350mA, constant-current power source as provided by this supply. In many respects, the circuit operates like a conventional step-down (buck) switching regulator.

Transistor Q1 is the switching element, while inductor L1, diode D1 and the 100mF capacitor at the output form the energy transfer and storage elements. The pass transistor (Q1) is switch-ed by Q2, which together with the components in its base circuit, forms a simple oscillator. A 1nF capacitor provides the positive feedback necessary for oscillation. The output current is sensed by transistor Q3 and the two parallelled resistors in its base-emitter circuit.

Circuit diagram:

1W LED Driver Circuit Diagram

When the current reaches about 350mA, the voltage drop across the resistors exceeds the base-emitter forward voltage of transistor Q3 (about 0.6V), switching it on. Q3’s collector then pulls Q2’s base towards ground, switching it off, which in turn switches off the main pass transistor (Q1).

The time constant of the 15kW resistor and 4.7nF capacitor connected to Q2’s base adds hysteresis to the loop, thus ensuring regulation of the set output current. The inductor was made from a small toroid salvaged from an old computer power supply and rewound with 75 turns of 0.25mm enamelled copper wire, giving an inductance of about 620mH. The output current level should be trimmed before connecting your 1W LED. To do this, wire a 10W 5W resistor across the output as a load and adjust the value of one or both of the resistors in the base-emitter circuit of Q3 to get 3.5V (maximum) across the load resistor.

Author: Nick Baroni - Copyright: Silicon Chip

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Fuse Box 1991 BMW 325i Diagram

Fuse Box 1991 BMW 325i Diagram - Here are new post for Fuse Box 1991 BMW 325i Diagram.

Fuse Box 1991 BMW 325i Diagram

Fuse Panel Layout Diagram Parts: Headlights, High beam indicator, Headlights, Auxiliary fan, Lights/Turn hazard warning, Active check control, Glove box light, Electro-mechanical convertible top, Wiper/washer, Stop lights/cruise control, Active check control, Antilock braking system, Cruise control, Map reading light, Rear defogger, Injection electronics, Ignition key warning/seatbelt warning, back-up lights, Tachometer/Fuel economy gauges, Injection electronics, Brake warning system, Cruise control, Injection electronics, adio, speedometer, on-board computer, Headlights, Heated seats, Power windows, Auxiliary fan, Interior Lights, Power mirrors, Heater/Air conditioning, Auxiliary fan.

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Fuse BOx BMW Z3 Underdash 1996 Diagram

Fuse BOx BMW Z3 Underdash 1996 Diagram - Here are new post for Fuse BOx BMW Z3 Underdash 1996 Diagram.

Fuse BOx BMW Z3 Underdash 1996 Diagram

Fuse Panel Layout Diagram Parts: ABS system, motorsport, airbag, air conditioning, automatic transmission, anti theft sytem, cigar lighter, clock, connector for optional, cruise control, cruise seats adjustment, electronic immobilizer, exhausy gas diagnosis, fuel pump, headlight cleaning system, heated seat window, heated blower, brake light, parking light, reversing light, side ligth, low beam headlight, interior light, high beam headlight.

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Cell Phone RF Radiation Detector LED

From rookieelectronics: This is my favorite project, its too simple and very interesting because it does not require any voltage source. it converts RF frequency waves from cell phone (whenever you call or send a text) to little current to flash a LED.

Actually this project is also called as LED power meter, it is used to test RF equipments. It can detect output power of our FM transmitters, by simply connecting voltmeter in the place of the load(LED) of this circuit.

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Use Of Alignment Tools and Dial Indicators Zurn Coupling

Use Of Alignment Tools and Dial Indicators Zurn Coupling

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LTC3605A – 20V 5A Synchronous Step Down Regulator

The LTC®3605A is a high efficiency, monolithic synchronous buck regulator using a phase lockable controlled on-time constant frequency, current mode architecture. PolyPhase operation allows multiple LTC3605A regulators to run out of phase while using minimal input and output capacitance. The operating supply voltage range is from 20V down to 4V, making it suitable for dual, triple or quadruple lithium-ion battery inputs as well as point of load power supply applications from a 12V or 5V rail.

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Simple Water Activated Alarm

The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and emitter and the transistor switches on. A larger current flows in the collector circuit enabling the 555 osillator to sound.

Simple Water Activated Alarm  Circuit diagram :

An On/Off switch is provided and remember to use a non-reactive metal for the probe contacts. Gold or silver plated contacts from an old relay may be used, however a cheap alternative is to wire alternate copper strips from a piece of veroboard. These will eventually oxidize over but as very little current is flowing in the base circuit, the higher impedance caused by oxidization is not important. No base resistor is necessary as the transistor is in emitter follower, current limit being the impedance at the emitter (the oscillator circuit).

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2500W Phase Control

This circuit controls resistive and inductive loads up to 2,500W. Its main functional device is an integrated phase control circuit - Siemens TLE3103. It contains its own power supply, a zero voltage crossing detector circuit and a logic driver. An additional feature is the low voltage input to enable/disable triac firing enabling/disabling the logic driver. The function is as follows: pin13 TLE3103 open (floating), trigger output active, tied to ground trigger output disabled.

2500W Phase Control  Circuit diagram

An UP and a DOWN button control a 32-step digital potentiometer (IC2, AD5228) via the debouncer IC1 (MAX6817). The potentiometer has a power on reset pin which might be tied to ground causing the potentiometer to start at midscale, or to VCC causing it to start at zero scale. The desired function is selectable using jumper JP1. The triac (capable of driving 40A loads) is a bit overkill for the desired power but the BTA41 has an isolated body and therefore handling of the board under voltage is less dangerous as it is with phase on the package. The circuit uses a 68μH inductance, but this might be replaced with a 100 resistor, then replacing the inductance C5 should have a value of 47nF.

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