4 Bit Optocoupler Isolator Module,PLC Signal Level Voltage Converter Board Module (3.3V to 24V)

Not cheap for what it is but did the job I bought it for great (adding some buttons to an ESP32 with long cables in a noisy environment).

This unit will control other sets of LEDs that require a higher amperage than my led circuit could deliver.

Opto isolation is a really good idea when working on electronics where there is a hot side, something with a higher voltage than your logic side.Optos use a light emitter and photodiode encased inside the chip, in this case the circuit offers an isolation from 3.3V to 24V, in practical terms you can use this connected up to an output on day a raspberry pi (or pico) and use it to turn on or off something that is powered by 12V, safely, there is. I physical connection between the 3.3V and 24V side.When you drive the 3.3V side, the led inside the chip turns on and the photodiode detects this and allows the 12V to flow through the chip, effectively allowing you to turn on and off a 24V signal from a 3.3V signal.The Advantage of using a opto is that even in the case of some short circuit or surge, the hot side cannot damage the low side, until you get up to several kilovolts where the current may jump.This board is available in a number of different versions, changing any given level to another, this board is the 3.3 to 24 volt version, but if you need a mix you can actually remove the resistor on the side you want to change, and make it operate with different voltages, it’s very easy to do.These boards are really cheap and there’s not really a whole lot else to say, they’re good value for money and they do exactly what they do, isolate signals!