View Full Version : H-BRIDGE PROBLEM

05-30-2009, 07:18 PM
hi friends,
i built a h bridge circuit i found on net here


and it works fine when it test it on breadboard there is no problems , but when i connect it to my MCU and ran it the transistors heats up very much now iam confused please help

05-30-2009, 09:01 PM
Check how much current its using , Whats the rating of your motors ? I hope u giving right inputs as this is a smokable hbridge !

05-30-2009, 10:03 PM
@snk_naveen: Who ever said that it is a smokeless H-Bridge, lied. :p
What is the input voltage that you are giving to the transistor? Is it more then 5v? Also, I highly recommend an reverse EMF protection diode in this circuit. Secondly, avoid floating inputs to the h-bridge at all costs, so use pull-up's on the uC output pins.

Hope this helps,


Debu :)

05-31-2009, 11:38 AM
Better use L293d IC

05-31-2009, 11:42 AM
yes iam giving 5 volts and iam using a motor like this , that i found it in toys


is the load in this motor too high for the transistors to take ??