Two buttons Safety relay

Posted on Jan 4, 2013

This circuit turns on a relay when two buttons are pressed at the same time.The relay backs off after few seconds, then the buttons have to be released and pressed again. This feature is often required in industrial safety.

Two buttons Safety relay
Click here to download the full size of the above Circuit.

Two button control relays are used in industrial safety in order to keep the operator's hands away from the dangerous parts of the machine. This feature is often required by the safety regulations.
Just for fun I designed and tested a curcuit that activates a relay by pressing two buttons at the same time, with a tolerance of 0,5 seconds. The relay is supposed to work instead of the pedal switch.
Once the circuit is supplied the input voltage (pin 2/6) is high, so the output keeps the low level.
By pressing one button the second transistor is supplied by 560Kohm, too high; so the collector keeps almost off and the input voltage is...

Leave Comment

characters left:

New Circuits



Popular Circuits

Moto Alarm
SWR Meter
Digital Levels Scope Displays 2 Logic Signals On 1 Scope
Vlf Converter
Headlight Flasher Circuit
Audio Gambar Skema Condenser Microphone Amplifier
Infrared alarm barrier circuit
BTL Mono Amplifier With DC Volume Control Circuit
timer 555 schematic
interfacing to microprocessor
Water Level Alert
high resistance voltmeter circuit diagram
bedini cole window motor
Zener Diode Tester Test Gears Circuits Schematics
Refrigerator working principle circuit indicator
XTR106 and send RCV420 composed of 12V power supply reception circuit diagram of the ring