Despite several warnings in AoE I have been evaluating a self bias stabilisation based on Ebers-Moll and retained phantastic results. We know the Vbe decreases lineary with temperature, whereas hFE is inversly proportional to absolute temperature. With completely different bias points than usual it is possible to get a stable behaviour using the intrinsic relations within the BJT. A smart application would be a current source(100ppm/K) for 350mA Lumileds for Joe Average, with a BD139 and a couple of resistors, that can be directly driven by a 3.3V PIC. Or a LED driver for Boki. Very good also for power amp self-biasing. I developed very simple formulas for the resistor values and methods to determine the necessary parameters. Anyone interested?
- posted
18 years ago
-- ciao Ban Apricale, Italy