Compactron Regulated Power Supply

[denny9167]

Has anyone tried this particular power supply for any projects?

[artosalo]

The possible probelm with this circuit comes from the low amplification factor of the triode of 6JZ8.
The PSRR of the whole regulator is only some 33 dB at best.
If the triode were hi-mu type like 12AX7, the PSRR would be more than 10 dB better.
The regulation of the output voltage is also better with hi-mu triode.
The PSRR can be improved some 10 dB by connecting a 220 nF capacitor between the output of the regulator and the grid of the triode of 6Jz8.

For most applications 6JZ8 works surely well enough.
I have used similar circuit, but built with 6L6GC and 6AU6.

[denny9167]

Originally Posted by artosalo

The possible probelm with this circuit comes from the low amplification factor of the triode of 6JZ8.
The PSRR of the whole regulator is only some 33 dB at best.
If the triode were hi-mu type like 12AX7, the PSRR would be more than 10 dB better.
The regulation of the output voltage is also better with hi-mu triode.
The PSRR can be improved some 10 dB by connecting a 220 nF capacitor between the output of the regulator and the grid of the triode of 6Jz8.

For most applications 6JZ8 works surely well enough.
I have used similar circuit, but built with 6L6GC and 6AU6.

Thanks for the suggestion, would it help to use a VR tube instead of the neon bulb?

[211hojbjerg]

Hi reg's
it is correct that you can improve by using a hi mu triode, however a pentode ca give you mu of 1000-1500, EF184
you can improve just by connecting the pass tube as a pentode, with well regulated g2.
I use EF184 and EL34 im mu reg psu, both connected a pentodes.

best regards
karsten

[artosalo]

Thanks for the suggestion, would it help to use a VR tube instead of the neon bulb?

VR tube is OK, but why not a simply a zener diode (48 V...).

[Tom Bavis]

A way to put those 17JZ8s to work...

6LU8 or 6MF8 is the same pinout and has a higher mu triode, higher power Pentode too.

[denny9167]

I'm curious the tube data sheet says the maximum plate voltage of this tube is roughly 250V,and yet isn't their at least 300V being applied to the anode of the feed through tube?

[SY]

That rating is for plate to cathode.

[Miles Prower]

Originally Posted by denny9167

Has anyone tried this particular power supply for any projects?

Yep.

My design uses the same basic topology, however, I'd bet mine performs better. A single triode for the error amp isn't going to give very much open loop gain, and will compromise the closed loop error correction, and therefore, the voltage regulation. That's probably OK, if you don't need tight regulation, but that's OK for a basic, adjustable bench supply.

For good performance, you need better in an active screen regulator, both in regards to voltage regulation and Zo -- both of which improve with increasing open loop gain.

For a 40V variation in DC rail voltage, this regulator showed an output voltage variation of 0.8Vdc for the required 270Vdc for the screens of Class AB1 807s.

Not too sure about using a neon panel lamp for the reference, as these aren't rated for a lot of current. A voltage regulator VT or a voltage reference VT would be a better choice.

[denny9167]

I appreciate all the input, just finished the power supply,with excellent results. I'm using it to power a tube based buffer preamplifier,requiring only 150V B+. The sound is marvelous!!!!! Dead Quiet!!!!!