Bank Account Protection Circuit for Motors

Protects electronics (and your bank account) that share a power supply with servo motors.

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PCB and BoM for Returned Energy Dump circuit to protect electronics that share power supply with a servo/stepper motor.

Oops. This wasn't supposed to be published yet, but since the cat is out of the bag, I may as well provide more details. 

Please note that I have not received the boards yet so I haven't been able to test the circuit. I am expecting the boards to arrive in a few days and will build one and test it as soon as they arrive.

When I was working on the sand table Arrakis I made a small error and ran the mechanism into the end of the Y axis at 1500 mm/sec. The abrupt stop converted the kinetic energy in the motors to electrical energy that was dumped onto the power supply rail. It happens that I had a Duet controller board and a couple buck converters to power LED strips connected to the same power supply as the motor. You can guess what happened: the power supply, Duet board, and buck controllers all bit the big one, shaving about $200 out of my savings.

This circuit came from an app note at Gecko Drives. I just selected parts and designed a PCB using KiCAD. 


BoM (mine):

Gerber and Drill files:

KiCAD project file:

I'm not entirely sure how high the supply voltage can be for this, but the PCB traces and the diode I used are good for 10A continuous. I don't know how high the voltage spike at the motor side will be when the motor is in a fault condition. I use 24V iHSV servomotors so I'm confident this circuit will be fine. It's probably OK for 36V motors, too, but I have no idea if it would be good for 48V or higher motors. R1 may need to be bumped up to 1 or 2W...

Stay tuned for test results...

  • Boards are in

    Mark Rehorst02/03/2022 at 21:39 0 comments

    I received the first set of 3 boards from OshPark. I'm waiting on backordered parts from Mouser so I can build them up- the crimp terminals for the plug that mates with the board connector are out of stock.

    I think I may change the footprints for R1 , R2, and D1. The diode and resistor diameters are a bit larger than the footprints I used to make the board, so things may get a little tight.

    If I do a new version of the board it will get posted here, in the meantime, here's what the rev 01 boards look like:

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