Self Control

Jan 1, 2011

I’m proud of myself. The unit in the picture is a board I designed and created on my own. I mean, I had a board company take all of my drawings and produce the PCB professionally, but that’s my work all the way through. It controls 4 separate DC motors in forward, reverse and PWM in between, and is powered by an outboarded 12v power supply and controlled by an Arduino.

I used Pad2Pad to create the board from my design schematic. I used Toshiba TA8050P controller chips for the motor drive and use bi-colored LEDs to show motor direction. It’s actually a fairly simple circuit, but I have the power supply (DC to DC converter) onboard and the thing is capable of putting out 6 Amps total across the 4 motor outputs. With heatsinks on the Toshiba chips, I could probably push 8 Amps through. I also added a regulated 5 volt tap so there was power available for sensors or other components. The power supply was built to be reverse polarity and short circuit protected, and uses a TIP42 to actually provide the real supply output. The 7805 only can push an amp and a half, but using the 7805 to control the voltage throughput of the TIP42 provides regulated power at high current. I spent $100 having the board made and probably could have built it myself for a lot less. The circuit is simple enough that it could be easily drawn with resist pens on single sided copperclad. But I got all tricky and spent the big bucks to have a dual sided board and silk screened writing marking the parts, circuit, and my pseudo company name, Dogear, inscribed on it.

The top LEDs show power on and power out and the 4 LEDs next to the chips show motor power and direction.  I’m not sure why the TA8050P is less well known that the L293 or L298 motor controller components. It puts out higher power, takes a simpler circuit, and will do everything the better known chips will.  I used female headers as the sockets for the TA8050P chips, making their replacement a snap should I over burden them at some time.

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