Let's Make Robots!

do you think this would work if i wired it up to a picaxe 14M

ok this is a circuit i have come up with to try and not use a motor driver for my picaxe,

i will have the base transistors connected to pins of a picaxe 

i will appreciate your input 

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That is an improvement. You are missing:

  • A resistor (about 1k is good) between each Picaxe output pin and the base of each transistor.
  • The diodes in the schematic CtC posted are their to protect your circuit from the back-EMF that will happen when your motors stop. You should definitely include them.

Other than that, this will work, with the following extra notes:

  • The transistors you use must be able to provide enough current for your motors. I don't think you have told us how much current your motors pull (free running and stall), which transistors you want to use.
  • Notice in CtC's diagram how two transistors are NPN and two are PNP? That's good practice because the H-bridge won't short out if you wind up with all output pins set high due to a microcontroller reset or coding error.

Search this site for 'h-bridge matrix' for some good examples.

That way the motors will get 9 volt positive but no negative signal. In your drawing you only used s1 and s3.


You have to connect the transisters crossed: In this example they are switches. If you close s1 and s4 at the same time, the motor wil turn. When s2 and s3 are closed the motor turns the other direction. NEVER turn switch s1 and s2 (or s3 and s4) on at the same time!! as it will be a shortcut and you will blow your transisters.

ok i had a look at it i think this will help me abit more thank you