Using Motor Bridges

Posted on Feb 7, 2014

Bridges allow your robot to control high current motors. They literally `bridge` between the low-current logic circuitry of your robot`s brain to the high current demanded from the motors. Many, but not all, use the common `H` arrangement of control circuitry (usually power transistors) to provide on/off and directional controls to the motors - h

Using Motor Bridges
Click here to download the full size of the above Circuit.

ence the oft-cited name H-bridge. Though often considered "old school, " motor bridges using relays solve a number of problems, and easily provide for handling motors demanding many amps of current. Especially when purchased surplus, relays offer a cost-effective means to control your robot`s motors. The following two circuits were contributed by robo-maestro Russell Cameron. Circuit 1 is a hybrid solution using a DPDT relay for controlling direction, and a power transistor for on/off control. The transistor can also be driven in low-frequency PWM (pulse width modulation) mode for controlling motor speed. Circuit 2 is a half-bridge using a SPST and SPDT relay and transistor-controlled logic to manage on/off and direction. The bridge requires a split supply (two sets of batteries), and is well-suited for use when driving those small toy motors that are meant for 3V operation. (Like all split-supply drivers, one set of batteries may deplete faster than the other, depending on the driving habits of your `bot. ) A very popular and reasonably priced all-in-one H-bridge motor control IC is the L298. It can control two motors, not just one. It can handle 2 amps per motor, though to get the maximum current be sure to add a heat sink. The L298 has a large cooling flange with a hole in it, making it easy to attach a homebrew metal heat sink to it. If there`s a downside to the L298 it`s that it comes in a special Multiwatt 15 ...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Car PC MP3 Player
    Interfacing Alphanumeric LCD To Microcontroller
    Busy Telephone line Indicator
    Digital Clock
    Brake Light Signal Module
    FAN7710 Ballast Control circuit design
    AM radio circuit chip