i am using these modules for a project:
I drive them with a Wemos D1 mini via PWM and without a load, my 12V can be regulated fine from 0 to ~11V.
They have only 3 Pins on the circuit where the load is to be connected, Vin, Load and GND. So i connect 12V to Vin, the loads (+) to Load-Pin and both the powersource and motor (-) to GND.
As soon as i connect a load though, the voltage drops to zero and the LED on the module lights up, as it also does, when i turn the voltage to 0V via PWM. I tried that with an RC Heli Motor ( esky 180er ) and the intended load, a rumblepack. Both loads run fine when directly connected to 0 - 12V.
Update: I added a diode to prevent backflow of currency because of the motor and measured... with the motor attached, Voltage on the Load Pin is 0.63 instead of 11V when full ON.
Help my noob brain please!