Parallel BJTs

Thread Starter


Joined Apr 2, 2009
How to connect two or more power BJTs without ballast resistor?

I done this by FETs. It was NTC, more current, more resistance, so it would self-regulate. But i heard that a BJT was PTC, so i thought if current is imbalance, it will catastrophically failed.


Joined Feb 4, 2008
Yes, this is true nut BJTs have a NTC.

If you parallel BJTs the hottest one will conduct more and more current and finally it will be destroyed.

MOSFETs are good for paralleling due to their PTC.


Joined Mar 24, 2008
Actually Hughs did it quite nicely with their gap welders, and the early models were germanium no less. The trick is to use low ohmage resistors to balance the load somewhat, and match the transistors if you have the know how.