piclist 2000\11\02\115649a >
Thread: Protecting a BJT
face BY : David VanHorn email (remove spam text)

>> I am driving a 24VDC motor, draws < 1A, with a TIP121 that pulls down the
>> motor's negative side. I switch this motor on and off regularly (about 10
>> seconds on, 30 seconds off). I have found that the transistor becomes short
>> circuit after some time (days or weeks) and then self destructs due to the
>> continuous conduction and overheating. Has anyone experienced this or know

Do you have a protection diode from the collector of the transistor back to
the motor's supply?

You are trying to instantly stop the current through an inductor, which
will get you in trouble every time.

Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

http://www.piclist.com hint: To leave the PICList


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