Railway Points Sequencer

Dedicated variation rail fanatics using sophisticated train and points controllers regularly have the drawback that as their formats get greater and more advanced, the transformer offering power to the points does not have sufficient present to change a couple of points at the comparable time. The actuators within the points are designed for ac operation so it doesn’t assist via rectifying the provision and including reservoir capacitors, the coils can overheat and burn out if they get jammed throughout their shuttle (ac operation if actuality be told assists to beat friction in the mechanism). The circuit shown right here clear ups this drawback by means of using a sequencer to ensure than only one points actuator can be energetic at any time limit. During operation the controller will switch all the factors on one line concurrently normal, but the different connection to each and every coil is connected to the sequencer unit. This circuit will simplest enable present to flow through one coil at a time. 

Circuit diagram :

Railway Points Sequencer Circuit Diagram

The sequencer circuit consists of a 555 timer configured as an astable multivibrator clocking a 4017 Johnson counter the place the ten outputs are used to modify ten triacs in sequence, enough for ten units of factors. P1 alters the oscillator frequency of the 555 timer and can be adjusted in order that every time interval of the sequencer is lengthy enough to permit the points to modify. 

The switching time varies depending on the type of factors however is usually between 1 s and 1.5 s. Any points that jam during swaping give out a characteristic humming noise in time to the swaping frequency so it makes them more straightforward to find. The eleventh output of the 4017 can be linked to an LED (together with a sequence resistor). This will flash to present a visual indication of the sequencers operation. Power for the circuit is provided through 15 V ac from the points transformer. The B80C1500 bridge rectifier (80 Vpiv, 1.5 A) and regulator IC1 produce a stabilised 12 V for the circuit. Current consumption is only a few milliamps.

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