Let's Make Robots!

Big Hybrid H Bridge motor driver, inspired by CtC

Run 2 Motors, Fwd and Rev with PWM

I found this site for almost a year ago and I must say it is incredible! Full of useful information and creative, helpful people!

When I saw Chris the Carpenter driving around with Walter I just couldn't help my self wanting to be able to drive 2 * 12V motors with speed-control from a microcontroller. Think about what you can do! :D

Chris motor driver (witch is used in Walter) can be found here:


It was originally designed by BaseOverApex and modified by robologist.


I have to thank this community for its "open source"-minded thinking. It has ben fun and interesting reading trough the old posts on this site about making a big motorcontroller. Here are some of them:







This is my version of the motordriver designed by BOA (robologist mod).


Today I soldered the last parts on the board. I have just had time to test that channel A is working, but it feels so fantastic that it is working so I just had to post this.


The building process:

planing MDC

The plan in eagle cad. This is the second circuit I ever made, so it's not that fancy, but it works.


Messy desk

Cutting the PCB with a scrollsaw.

Ironing the pattern.

Soaking the paper.

Toner transfer complete

Etching the board!

Removing toner with acetone.

Drilling holes.

Board bottom side.

Board topside.


Components in place!!

Had an old oversized heatsink from an old amplifier.

Board complete, it is now in the "test, analyse and evaluate"-stage.

-And also a thanks to djhesit8, you know why! ;)


We might be seeing this board in action in the near future.

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Yeah, I'm fully aware of the "slamming" problem caused by the ratings on the relays (15A), and will try to code around it. I don't think any motor driver in this class can manage to
slam motors from full forward to reverse with a load.

Now I will have to choose whether to have one big fuse or have one for each motor. And if I use normal or reset-able ones and what values.

Then there is the other problem you mentioned. If (or when) the mosfets burn, they will burn closed so that the motors will be left spinning at maximum speed.
I'm thinking of adding a kill-relay depending on how I am going to control this thing. For now I only got components for controlling it wirelessly with a Sony remote :).
Maybe I will have to have a different brain to listening for the "kill" command.

I think I will buy 2 cordless drills for 10€ a peace and go from there.

Here is a quick video, my pocketcamera was out of juice so I had to record it on the phone. Just speedcontrol from one channel, no fed/rev. 


PS. My friend will lend me a cheap MIG-welder for a year. :)

Awesome! And props to you for giving credit to those who inspired you.

Can't wait to see it in action.