some people mentioned BJTs as another way to dissipate the energy into heat. They are current controlled devices tho ... how could they be implemented in a similar fashion? can anyone give examples of a circuit that uses a BJT?
I would imagine they are probably cheaper and higher rated than the IGBTs ![Huh? ???](https://www.eevblog.com/forum/Smileys/default/huh.gif)
I might be able to use a FET for the precision and the BJTs for the bulk of the load
The company, TDI (Transistor Devices Inc, now astrodynetdi.com ?) has made dynamic loads (Dynaload) for many years and we have bought and used many of these from E-bay for the past 25+ years. They have different modes, constant voltage, constant current, pulsed, external control, etc....
They used TO-3 BJTs in parallel and emitter resistors, just like an audio power amplifier, for transistor sharing. Also good heat sink and fans for cooling. We have had to fix a couple of them and we would replace the BJTs with better parts like the On-Semiconductor MJ15024 parts or similar. The old ones at least used not very good BJTs like, 2N3055s as I remember. MJ15024 (and that general family) are 250V parts with a good SOA and we used these in audio power amps for many many years as well as other amplifier companies.
I didn't think you needed higher voltage ?
boB