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CCS for small signal pentodes
Posted:
Wed Jan 11, 2017 5:50 pmby DeathRex
I was thinking of using a 717A as a small signal amplifier, (I haven't worked with small signal pentodes) but gain depends a lot on the anode resistor. If I wanted high current I would need a low resistance and I would get low gain. If I wanted gain of 100 - 200 I would need a 100Kohm or higher resistor. It seems a perfect place for a DN2540 - LM334Z CCS (I haven't worked with CCSs either). Has anyone tried them together>
You can look at 6AK5s data sheet for curves.
Re: CCS for small signal pentodes
Posted:
Wed Jan 11, 2017 7:39 pmby Geek
I'd use a cascode bipolar. Pair of MPSA92, couple red LED's and a pair of resistors. Better load impedance than both, superior PSRR than single DN2540 and the LM334 isn't good above 40V.
Cheers!
Re: CCS for small signal pentodes
Posted:
Wed Jan 11, 2017 7:46 pmby DeathRex
I was thinking about cascoding them like Shannon shows
hereExcept I would run it at about 5ma, cause peak current is 10ma.
Re: CCS for small signal pentodes
Posted:
Thu Jan 12, 2017 3:54 amby Geek
That's a good idea
Re: CCS for small signal pentodes
Posted:
Thu Jan 12, 2017 9:50 amby DeathRex
To use a DN2540 and LM334Z as a source, would I need a gate stopper resistor for the DN2540? Would that be the only change?
Re: CCS for small signal pentodes
Posted:
Thu Jan 12, 2017 1:01 pmby Geek
Always use a gate stopper.
Nothing will change, since you're working with DC.