Opto switching to replace mechanical button

Thread Starter

dcd528

Joined Jul 28, 2011
42
I have a battery operated circuit that is triggered by a mechanical push button. What optical component could I use that when I cover it with my figure it triggers a mosfet. 4.2 v battery.
Want an optical button I guess.
The push button triggers the mosfet which switches a large resistive load. Nice to change the mechanical button to a touch sensor or ir sensor
 
Last edited:

dl324

Joined Mar 30, 2015
9,093
Post a schematic of how the mechanical switch triggers your circuit so we don't have to play 20 questions.
 

James55

Joined May 29, 2016
39
You may want something along the lines of this

Basic Optocoupler NPN circuit.png

...which was taken from a Lewis Loflin video on Opto circuits which you can watch here....


Good luck
 

dl324

Joined Mar 30, 2015
9,093
You could use a voltage divider consisting of a light dependent resistor (LDR/photocell/photoresistor) and resistor on the gate of the N channel MOSFET.

For more abrupt switching action and/or hysteresis, you could add a comparator.
 
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