Same Ground for Optocoupler

Thread Starter

jacopo1919

Joined Apr 12, 2020
41
Hello!
I need to control a on-off state of a device via a GPIO output of a raspberry Pi and both units are powered from the same power supply.
For this purspose i want to use an optocoupler to act as a ''switch button'' but the 2 units are going to share the same ground.
Is this going to cause problems of any sort?
greetings
 

Thread Starter

jacopo1919

Joined Apr 12, 2020
41
I'm trying this because i want to replace a physical on/off button of a specific device with a message coming from the raspberry pi's GPIO.
i mean to use it this way:
The raspberry send a 3.3V message (max V out level) to one side of the optocoupler to make it act as a switch for the other side which is tied to 3.7V (this is coming out of a 3.7V voltage regulator, but starting from the same power source).
Basically this would allow me to transform a 3.3V switch into a 3.7V switch and to replace a relay.

The 2 grounds of the optocouplers are going to be the same though, because the power supply is the same...
 

nsaspook

Joined Aug 27, 2009
8,382
How much current does the 3.7V load require? Because this application doesn't seem to require galvanic isolation I would use a device designed for load switching with a 3.3V input instead of one designed for isolation.
 

BobTPH

Joined Jun 5, 2013
3,308
Show us how the switch you are trying to replace is connected. And tell is how much current it must carry. Then we can help you design what you need.

Bob
 
You can use an opto-FET or optoMOS relay. Some of the OPTO-MOS relays only require 1mA for the LED.
You sometimes don't need the low on resistance or the current carrying capability. they are great for switches in a matric.
 
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