Now this little baby of a H-Bridge DC Motor Controller works like a charm and looks great. Examine the PDF for some great details. The clear plastic top is nice as you can see the inner workings with Leds flashing. The Power Led comes on to show you have power and the unit is ready to go. Push one button and the motor will rotate and the Led next to the button comes on to show the motor is moving. Push the other button and the motor will rotate in the opposite direction and the Led will turn on to show it is moving.

I think I have this box making and labeling down to a pretty good art. The is the third try on making a decent H-Bridge DC Motor controller. Consult my other revisions for details on some of the issues I have solved with this one.

The back panels are real tidy as you can see from the pictures. Notice the use of the molex connector from computer power supplies to run power in and DC drive power out to the motor. I also have an abundance of DB9 and DB25 connectors which are great for running signals here and there. So the box is portable and could run DC motors in another machine if so desired. In this case it is for my Side Hill Gouger project but it would work fine for any other DC Motor that you wanted to move. It will operate at 12Volts or 24 Volts and produce up to 10 amps of drive current.

The construction of this circuit is explained in the circuits section under labeling. The wires on the right are to the back panel, while the wires on the left go to the front panel. The switches and Leds shown were just for testing before I boxed it up. Note the fuse on the right for protection. Also note the jumper on the right of the board for selecting +12 Volts or +24 Volts Motor drive. The amber Leds beside the MOSFET drivers are bicolor, and change color when the MOSFET is turned on. The H-Bridge configuration is nice to see in action as A-C will turn on for one direction and the B-D for the other direction. The clear plastic cover makes it nice to see it in operation with flashing Leds and should be great for troubleshooting if anything ever goes wrong---goes wrong--goes wrong!

The layout on the left is a block diagram of the components used in the circuit. Note the MOSFET and PNP darlington used for drive (B) and (C). You have to look close in the previous picture as they are fastened to the same heatsink More will be said about this in the later discussions.

It is mainly to show the addition of the TO220 package for the darlington bipolar transistor and the associated resistors.

The diagram on the left is to help in the main power wiring and is meant as an aid to make sure things are kopesthetic. It is will explained in the H-Bridge Rev 1 discussion.

The block diagram on the left show more details on wiring in some of the modification to the MOSFET drivers. I added appropriate resistors to the gates of all the MOSFETS just to make sure they wouldn't pick up a stray turn on signal. The drive on (B) and (C) has changed with the addition of a PNP darlington transistor as the working driver. The reason for this swap was when I operated the circuit with +24 Volts the P type MOSFETS at (B) and (C) just wouldn't get a low enough ground signal to turn on. This seems to be a common problem with operating P-MOSFETS at higher voltages. The gate turn-on voltage is very dependant on the Drain Voltage. Anyway my solution was very simple as I simply changed the driver to a darlington bipolar PNP transistor and used the old MOSFET as a turn-on for the transistor. I had lots of these great TIP107's and physically it was easy to bolt them to the back of the same heatsink as the MOSFET was on.

The schematic on the left is well explained in my REV 1 discussion. The changes I made with this final revision was to swap out the open collector 7406 to a ULN2003 darlington driver IC. I just didn't like to use the 7406 as it is a little darted and I didn't have too many of them. With the UNL2003 I was sure of my operations. Other than that all the gates are mainly used for led indicators which can never harm anything in the construction of a good circuit.

As always you can see great details on this circuit by examining the accompanying PDF.

Revised 2013 by Larry Gentleman