Review on ⚡️ 5V Relay Module for Arduino Raspberry Pi DSP AVR PIC ARM - JBtek 4 Channel by Antonio Curry

I would give 5 stars except it is active at low level. The problem with active low is that the outputs of many control systems default to low at power-up. Thus, the relays close on power-up until the default program starts and the system sets the outputs high. So in this scenario, if there is a power failure, an activated relay because the pin was pulled low, or ground becomes a deactivated relay because the power supply has been removed. So I think it's best to setup such a relay board as active high. Thus, the state of the relay during system startup is the same as when the power is turned off. I had to break out a soldering iron and dig out some resistors to get the board active high. I did this by desoldering the resistor on the anode side of the optocoupler and soldering a discrete resistor to the optocoupler's pin. I then soldered the input jack pin to the ground pin. I only use 2 relays so I made IN1 and IN2. DO NOT DO THIS if you have no idea how it works!