Author Topic: Darlington for output transistor  (Read 15256 times)

Crazyyellowfox

Darlington for output transistor
« on: September 30, 2009, 11:31:14 PM »
I'm not doubting that this has been tried, but an NPN darlington works nicely for the output transistor,
some tweaking with the biasing is required, but you can get a nice hot output with an MPSA13/MPSA14
I was also able to coax a darlington pair of two Russian NPN germaniums (mp10) to work for a nice
buttery midrange. in conjunction with two hfe-matched 2SB324 PNPs.

blackcorvo

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Re: Darlington for output transistor
« Reply #1 on: October 31, 2009, 04:59:51 PM »
i did some tests but i only have BC517 darlingtons, and AC107, that were the only germanium PNP transistors i could find here in my town. there's only one place that sells N.O.S. electronic components but they only gave me this model when i asked for germanium transistors... and this one is weird because the red dot close to one of the leads poits the Collector, and the usual - as i heard/searched - is for pointing the Emiter...
I also played with the diode a bit, trying Leds, Zenners, Germanium and Schottky. Myself i preffered the Zenner and the red Led, because they didn't clip too early like the Germanium and Schottky ones. About these two, i think the Germanium sounded best. The schottky sounded too compressed and distorted to my taste. i really like a louder output with less distortion for building clipping modules, so i can use a little trick: i put zenners just after the output capacitor, in way they do the clipping by their voltage, wich gives a little compression in the wave before the "real" clipping, then i put a small resistor in series with the output (nothing higher than 2k, usually 330R), and after this resistor i put the clipping diodes in the usual config. for me it sounds great.

that is another idea people couls use for building distortion circuits: putting clippers in a "cascade" config like that to get different flavours of distortion.

borman09

Re: Darlington for output transistor
« Reply #2 on: May 02, 2011, 01:52:05 PM »
An operational amplifier ("op-amp") is added in the circuit.