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Why transistor Vbe drops when is in active region? BC547 ib=constant

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harrimansat:
Above Vbe, below, Vce, ib=6uA , constant

magic:
I guess it's the Early effect, then.

It's well known that Vbe and Ib required for any given Ic decrease with increasing Vce.
Apparently, the Vbe for any given Ib decreases too.

harrimansat:
Does it increase or decrease?

In that graphic I see that increases, in my experimental measurements, and in the curve tracer it decreases

harrimansat:
Yes, it seems a thermal effect, tested today with a low speed ramp, with a constant 20uA base to emitter. Graph is Vbe, and Vce(60 secons slow ramp)

harrimansat:
I think the mystery is solved, for testing power semiconductors without heatsink the 576 has a pulsed base supply function, at 300us and 80us. It hadn't occurred  to use it for low power semiconductors. Without dissipation the return effect practically disappears. I leave you a video, I also heat the transistor with my fingers to see the effect.

Oscilloscope is connected to Vbe to see pulse duration



Thanks to all!

Best regards

Miguel

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