> At 09:13 AM 9/1/99 +0200, Imre wrote: > > White noise generator, design by dr. Imre Bartfai, 8/30/1999 > > > > +--------------------------------------------------------------------- > Vdd > > | 220k 220k > 5V > > | +---\/\/\---+ +---\/\/\---+------+ > > | | | | | | > > | Ge | |\ | | +------+ \ > > | EFT317 PNP +-----+----|- \ | | | / > 220k > > | C | | | >-+----| |----+ | |\ \ > > | |/ \ +-------|+ / 47n | +-----|- \ | > > +--B| 220k / | | |/ | | | >--+ > > |\ \ | | 1/2 LM358 +----------|+ / | > > |E | | | | | |/ \ > > +----| |----+--+ + + + / > 47k > > | 47n | | | | 1/2 LM358 \ > > \ \ \ \ \ | > > 4k7 / 1M / / 2k2 1M / / 2k2 + out > > \ \ \ \ \ > > | | | | | > > +-----------+-----+-----------------------+----+---------------- > Vss > Robert A. LaBudde wrote: > Where does the transistor collector go? Presumably to Vdd? (Unconnected as > shown.) > The collector is not connected. This circuit relies on the reverse breakdown of the Base-Emitter junction which produces a lot of noise. More or less the same as a zener diode, which can also be very noisy, although a transistor is usually worse (or better depending on your point of view). Regards Mike Rigby-Jones