Thread Starter


Joined Dec 2, 2023
Hello all , I want to make optocoupler relay PCB. the development board I'm using giving 3.3V as triggering voltage . can someone help me or please share the schematic diagram with me .

thank you


Joined Mar 30, 2015
Welcome to AAC!
  1. What is your definition of an "optocoupler relay PCB"?
  2. What is driving this board that makes you think you need electrical isolation?
  3. What are the relay specs?
  4. How much current can the 3.3V signal source?
We're here to help you, not do all of the work for you...


Joined Mar 14, 2008
A design requires specifications, and you have provided none, other than a vague description of what you want.
Please provide that as dl324 requested.
Also what supply voltage(s) are available?


Joined Jan 23, 2018
Visit the "Schematicsforfree.com website, then continue to the category of "control" and yo should spot the circuit that you need. Download the circuit and come back here for the explanation of how it works.

Without specifications, professional engineering rates apply. For each contributor.


Joined Mar 13, 2020

Times like this I think maybe I should offer a service as a "Finder". All I did was put Optocoupler Module in the Amazon Search bar. There are other options as well. Picked this one because it clearly states a 3.3V operational level. Not sure if it was in the specs for this one or for another, but typically 5mA is all that's needed to fire the LED inside the Opto. Once lit the Opto will switch a relay on. This one handles 10 amps through the relay.

Otherwise please state your requirements. Tell us what you're switching and why you feel the need to use an Opto.


Joined Jan 23, 2018
The module in the link uses a 5 volt supply and includes an amplifier transistor. So there is a fair chance that it can not serve as simply an opto powering a relay. And the amazon folks will be of no more help than the guy reading his paper at the bus stop.