Purpose of this capacitor in discrete amplifier?

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amplifierguru said:
Whether you're listening standing on your head with a drip feed of your favourite libation, it's still preferable to finesse the cct and, for a few cents more in componentry and science based design effort, be listening to JUST the music, yes? :D :D

That's my preference, anyhow.

Cheers,
Greg


I here you on that. If you are going to make homebrew, whether it be an amplifier circuit or "homebrew": drink, smoke, whatever suits you, there is no reason not to strive for the best. Otherwise it would fester bordem. Cost is a relative factor of course and learning from those with more experience than you is always key to the ending effect. That is what I like this forum, most people here are quite learned people.:)
 

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Hi Andy.

Very funny :D :D :D

Out of context mate. The post was about the PSRR of various diff'l tails. everyone knows what a 2BJT CCS is, but dimitri had to highlight a partly shown piece of the schematic. that's all. It was simply an experimental lash up and had nothing meritorious in itself to display so there was considered no need to show it.

cheers,
Greg
 
Hi Mastertech,

The diode in question was added to the 2BJT CCs for a reason - I needed a 1.2V active component across the 1.2k so I built up the BJT Vbe junction voltage with a diode. Why? because the CCS is temperature comp as well and either the diode or BJT were to be relocated to the heatsink. As the thermal comp required was half that of a std BJT I added an equal but non thermally connected component with a much smaller dynamic impedance than a resistor which would dramatically impair the CCS performance.

So I got my 2mV/degree in 1.2V, temp comp CCS.


Clear as mud.

Cheers,
Greg
 
Hi Dimitri,

I wanted a CCS that had a -Ve tempco of half that of a BJT so put the diode in the sensing leg and EITHER the sensing BJT or diode can go to the heatsink while the other monitors ambient. Simple low cost solution! As you're aware the simple BJT CCS has a normal 2mv/deg tempco of output current , this was simply my way of halving it.

Cheers,
Greg
 
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