Phototransistor 555 Timer


Posted on Jun 29, 2012

This page shows three circuits for using the 555 timer IC as a photocell controlled train detector. The circuit is shown driving light emitting diodes but any load of less than 200 milliamps could be used. Shown on the schematic is a secondary output that uses the open collector at the DISCHARGE terminal (Pin 7) of the timer. This output can sink a fairly large current and would be ideal for driving relays.


Phototransistor 555 Timer
Click here to download the full size of the above Circuit.

An optional resistor, R6, can be added to the circuit to lower and compress the detection voltage range but this only partially alleviates the problem of the wide detection band. The graphs at the bottom of the diagram show the input voltages at whic




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Car temperature indicator circuit
Bridge circuit
Long-Range IR Transmitter
Monolithic Synchronous Voltage-to-Frequency Converter
Electrical Single Line Diagram - Part Two
forester: window regulator to all the way down to install it
VCO Seiler 80Mhz-300Mhz
A crystal-controlled oscillator
DAC0832 interface circuit with the 8-bit CPU



Top