01-07-2013, 09:58 PM
Hi Kalee,
I hadn't thought about the other emitter going down......
The next bit is what interests me;-
On the other hand, power switching stages are fairly often operated with Vbe in reverse breakdown to get the best possible turn-off speed. Current flow and duration are limited thus excessive energy dissipation in the wrong part of the device doesn't cause any thermal problems.
The best efficiency I have achieved was driving Rev Vbe to about 10V but the Zener used for limiting at this voltage was getting a tad too hot (1W) device. It has now been replaced by 16 1N4007s. Quiescent input 2.5W.
Using a single 1N4007 reduces the efficiency and Quiescent input rises to around 7W with the device becoming hot on its' small heatsink.
The best Output was achieved at around 8V but the heating effect on the device was quite noticeable, Quiescent input around 4W.
Thanks
Mike
I hadn't thought about the other emitter going down......
The next bit is what interests me;-
On the other hand, power switching stages are fairly often operated with Vbe in reverse breakdown to get the best possible turn-off speed. Current flow and duration are limited thus excessive energy dissipation in the wrong part of the device doesn't cause any thermal problems.
The best efficiency I have achieved was driving Rev Vbe to about 10V but the Zener used for limiting at this voltage was getting a tad too hot (1W) device. It has now been replaced by 16 1N4007s. Quiescent input 2.5W.
Using a single 1N4007 reduces the efficiency and Quiescent input rises to around 7W with the device becoming hot on its' small heatsink.
The best Output was achieved at around 8V but the heating effect on the device was quite noticeable, Quiescent input around 4W.
Thanks
Mike
