Review on 🔌 SunFounder 4 Channel 5V Relay Shield Module: Compatible with Arduino R3 MEGA 2560 1280 DSP ARM PIC AVR STM32 Raspberry Pi by Grant Nordstrom

Although this product is well designed (as far as I can tell from the diagram on the manufacturer's website and the physical execution of the design, it looks solid). It's wrong to say that this can be driven from the microcontroller's standard logic level outputs. This requires an output capable of sinking 15mA of current when active. it is not a standard "logical level". That's not to say the rest is bad, it actually has opto-isolation between the logic-level interface and the actual relay coils, just in case you're worried about high-voltage isolation or coil-back EMF effects when the relay turns off (it has blocking diodes) EMF where they should be (hopefully they are correctly identified, working and properly aligned). both because it needs to draw quite a bit of current, and because the voltage might not be that friendly to your 3.3V logic. Requirements for my assessment: Working Systems Engineer (hardware/firmware) since 1978, EE from Caltech, Computer Science from the University of California.