LMD18200 – DC motor control adapter

It is a device that controls the DC motor with a gear, which drives a three-way valve mixing water for underfloor heating so hot water does not flow to pipes.



Just provide TTL compatible signals:

• Dir – responsible for the direction of rotation
• Brake – responsible for brake
• PWM – responsible for speed

This allows to make a precise servo motor from a simple motor and carefully position its axis. To do this, encoder should be used on the shaft or multi-turn potentiometer in the servo valve. This allows the microprocessor at any time to check what is the valve position. Additionally, the system has an output which informs about the current flowing through the motor winding. This allows to make protection against valve verve. It is really important. A motor with gear having 40Ncm torque was used.
Additionally, there is a PWM generator of own production on the plate. When there is no need to change speed while working, it can be set once and adjustable only by direction and the drive on/off.
Signal source on the PCB can be switched by a jumper.
The whole project was described in science portal – link:

URL Laboratorium badawczo - rozwojowe PROTON

Below there is a video:


Link to original thread – LMD18200 - adapter sterujący silnikami DC