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...
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,...
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...
Fire Alarm Using Thermistor
Small and simple unit, Can be used for Home-Security purposeIn 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...
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)...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
10 Amp Solar Charge Controller
The SCC2 is a solar charge controller, its function is to regulate the power flowing from a photovoltaic panel into a rechargeable battery. It features easy setup with one potentiometer for the float voltage adjustment, an equalize function for periodic overcharging, and automatic temperature compensation...
3W FM Transmitter Circuit
DescriptionThis is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isnt so bad, a PLL can be used on this circuit.This is a circuit that Ive build a few years ago for a friend, who used it in combination with the BLY88...
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Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. ... -
We have already seen in many of my earlier articles how triacs are used in electronic circuits for switching AC loads. Triacs are basically ... -
This project was a particular surprise for me in that the BC547 (equiv 2N2222) can be used to build a 500mW linear amplifier covering the en... -
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 telep... -
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 ... -
A filter removes the dc component of the rectified ac, which is then scaled to RMS. The output is linear from 40 Hz to 10 kHz or higher. Cu... -
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This circuit was designed to allow microphone cables or other cables to be easily tested for intermittent breaks that can often be difficult... -
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