Warning: Out of Topic. No relation to Devuan but to technology and electronics.
Since, I know some have knowledge of electronics and I am replacing an amplifier's pre-driver stages I am posting here. At present, I am opting to use a simple circuit for testing purposes. This circuit uses a differential pair and the input stage. The differential pair is supplied a pseudo-constant current (2.5mA) from a two resistor chain with a Zener diode connected to ground. This results in a fairly constant voltage that develops across one resistor and the base-emittor junction. Therefore, the bias current can be taken as constant. The output from the differential pair drives the pre-pre-driver stage which has its collector resistor replaced by a constant current source. This both provides a high impedance output resistance for this stage and solves issue of using greater drive current for the same output power. My little hesitation at the this stage, is the biasing to remove crossover distortion. I know a that two diodes are connected in series but I want more control on the quiescent current in the output stages as this can cause overheating and unnecessarily uses energy for no output. Together with two series connected diodes I found some amplifiers use also a preset resistor in series with the biasing diodes to have more control. In my case, I think the choice may be an amplified diode which is a transistor biased in such a way to behave like a diodes but with modifiable characteristic. The latter arrangement have the ability of presenting a voltage that ranges from 0.7V upwards whereas the former two start from 0.7 x 2 volts. Excuse me for my intrusion. Someone might have met or read about a biasing arrangement I have not heard of yet. Thanks. _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
