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H-Bridge Circuit

OK so I've been saying I'll do a circuit for an h-bridge for a long time, now I've been and done it. It's not meant for big motors just those small ones so ideal small robots. You'll find that H-bridges are an essential part in robotics for controlling motors, a similar design to this one was used in KTX1.

Component identity code Components that can be used
TR1 and TR2 are PNP transistors BC327 Sil PNP 50 volts 800mA
TR3, TR4, TR5 and TR6 are NPN transistors BC337 Sil NPN 50 volts 800mA
R1 and R3 need to be tested depending on the transistors used but I find that 100 Ohm resistors work well. <read100 Ohm ?
R2 and R4 again need to be tested, I use 1K resistors <read 1K ?


The components that are on the list are what I normally use but you can use different parts, so if you wanted a bit more current you could use ZTX transistors instead or if your a beamer and only have the 2N3904 and 2N3906 transistors you could use them although they can only handle 200mA.

How it works

By connecting input 1 to + Volts one side of the bridge will be turned on lets say the motor turns clockwise now if you disconnect input 1 and connect input 2 to + Volts the other side of the bridge will be turned on turning the motor anticlockwise, now it is very important that you never connect both sides on the bridge at the same time because if you do you will put a short strait across the power supplies and your transistors will fry (needless to say there never work again).









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