High Current Darlington pair

I have a 12v motor and a 12v battery with a 7 amp output and a 12v electric motor. What transistors in the darlingtom pair circuit should I use to accomadate the high current of the battery and at the same time provide an output of around 7A? I think the ones in the instruction diagram are too weak.

Posted by Anonymous on 21/12/2004, at 17:55 GMT

correction

I meant to say I only have 1 12v motor,my bad

Posted by Anonymous on 21/12/2004, at 17:56 GMT

Choosing a transistor

The current is determined by the motor (providing the battery can supply it). The battery may be capable of supplying 7A but if the motor uses only 2A that is all you need for the transistor rating.

First use a meter to determine the maximum motor current, this will be under load (not running free). Allow a little more for safety and choose a transistor which can pass this current. The TIP31C in the diagram can pass a maximum current of 3A. Consider a TIP41A (6A) or 2N3055 (15A) but there are many more, a supplier's catalogue should have details. Remember you will need a heatsink too.

For further information please see: www.kpsec.freeuk.com/components/tran.htm

Posted by John Hewes on 22/12/2004, at 10:16 GMT

High Current Darlington Pair

The TIP142 would probably serve your needs with a maximum collector current rating of 10Amps and 125W at 25c power dissapation. The higher rated MJ11015/MJ11016 darlingtons would probably need an extra driver transistor.

Posted by RW Neill (varient412@yahoo.co.uk) on 17/01/2011, at 11:03 GMT