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Relay Based Dual H-Bridge

Gives all directions for two motors

I designed this circuit for those interested in controlling motors that require a lot of Amperage, but have gotten frustrated over trying to create a MOSFET H-Bridge. I present to you a simpler design (yes it may take up more space) that uses only one MOSFET. This design allows the user to have two motors run forward, reverse, and have an electronic break. A single logic level N-Channel MOSFET (or a bunch hooked up in parrallel to increase the amount of current the circuit can with stand) allows for this H-Bridge to be PWM compatible! This circuit can also be re-engineered quite simply to use only three pins on a microcontroller instead of five, however doing this will not allow you to have an elctronic brake. Problems and Comments below :)








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For the voltage that is driving the motors, I am actually going to be using 24VDC in mine, but it will basically work from 0<x<55 Volts.

I do like your circuit but you may want change the location of where the motor ground path connects to the fet array.

I've I had this design for awhile and did not catch that! Thanks, you saved a lot of headaches, ill be sure to post an updated schematic!


I had to laugh whem I spotted this one.  Relay 5 does not need to be PWM'd by Pin 5; just connect its ground to the regular (unmodulated) ground. 


Happy Trails

I spotted that too. Haha yeah, I can picture the relay spasming out when the power is applied, very loud and annoying and probably would wear down the relay.

Is this the flaw you spotted in the original circuit? (Reference the updated one). Thanks again for helping me spot this problem! having the robot go full speed in reverse and not expecting it would have been potentially dangerous, thanks!

Additionally, just to be clear, the  ground rail for the motors should be connected to the mosfet rail where the 2s are located.

Thanks! Another pair of eyes is nice to have when its late at night, thanks for helping me edit this circuit!

Looks pretty darn good now.  I want to build it. :)

Alright! When I'm done building mine, ill post it up :)