Despite what may seem complicated at first, the photograph below includes added features such as an LP2954 5V voltage regulator, a bicolor LED, and two switches for testing. One H-bridge drives one motor. For a common two-wheeled robo. Despite what may seem complicated at first, the photograph below includes added features such as an LP2954 5V voltage regulator, a bicolor LED, and two switches for testing. One H-bridge drives one motor. For a common two-wheeled robot, obviously two copies of the H-bridge circuit are needed. (Click the picture above for a movie) 1. Pressing the ri. R1 and R2 are pull-up resistors. These can be any value from 10 kilohm to 100 kilohm. These make sure the inputs are both on unless a signal from the microcontroller tells one or the other to turn off. With both on or both off, the motor doesn't spin because there's no voltage difference between them. Think of these as default values. Unless a diff. IC1 is a dual MOSFET transistor driver chip. Anything from the TC4424 family will do. The MAX4427 and TC4427A is the same but with a lower amperage rating. The IXDN404 has the highest amperage rating (best choice). The DIP part can be purchased at DigiKey or Mouseras part #IXDN404PI. This chip provides two independent inputs that are compatible wit. My original source had D1 and D3 listed as small-signal diodes. I couldn't find any at the time, so, I used 1N5817 Schottky diodes instead. It turns out that Schottky diodes are much better for motor circuts because they react more quickly. The key factors in substitution are: 1. Are the diodes rated to turn on with less voltage than the TC4424's o. D2 and D4 are also Schottky diodes; the same as D1 and D3. D2 and D4 protect the chips from undervoltage (less than ground) by turning on when the voltage in the motor is below GND. Once again, the batteries take care of the problem, rather than power flowing backwards from the chip. D1 through D4 could be eliminated. In fact, Bugdozerruns without.
