A few years back, I was doing a search for various all tube power supplies and came across a General Radio supply that had a very interesting layout
the specs are fairly good, and it has some interesting features which include feedback, and the use of a 6AN8 triode as a cathode follower to control
the pass tube, although it uses some feedback to improve the gain of a cathode coupled pair of triodes, which I think is its primary weakness,
and since I had been using a 723 regulator in some projects, why not use the 723 for the reference/error amp instead of the 12AT7, and I came up
with this creation, it works well in spice, and breadboards nicely, I will need to fine tune some of the resistor values, but all in all not bad.
and it improves regulation greatly, both the reference voltage(7.25VDC) and error voltage are virtually spot on, about 0.01%.
the specs are fairly good, and it has some interesting features which include feedback, and the use of a 6AN8 triode as a cathode follower to control
the pass tube, although it uses some feedback to improve the gain of a cathode coupled pair of triodes, which I think is its primary weakness,
and since I had been using a 723 regulator in some projects, why not use the 723 for the reference/error amp instead of the 12AT7, and I came up
with this creation, it works well in spice, and breadboards nicely, I will need to fine tune some of the resistor values, but all in all not bad.
and it improves regulation greatly, both the reference voltage(7.25VDC) and error voltage are virtually spot on, about 0.01%.
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Note: I may decide to move to a 7AC pin out on the pass tube, so I can use a number of different tube types, ex: 6V6, 6L6, etc.
interesting. The 723 is one of the best regulators ever made so there is no quitestion in my mind that performance will be superb.
Here some constructive criticism: if you are going for a tube control amplifier that requires an extra winding: why not voltage double said winding to provide power to the 723, instead of dissipating quite a bit in the MJE340 source follower?
I was recently experimenting with TL783 maida style regulators, the circuit below is an experimenting supply capable of 1.25-350V 100mA output. its got a sink on the output to keep it stable at all load conditions.
Here some constructive criticism: if you are going for a tube control amplifier that requires an extra winding: why not voltage double said winding to provide power to the 723, instead of dissipating quite a bit in the MJE340 source follower?
I was recently experimenting with TL783 maida style regulators, the circuit below is an experimenting supply capable of 1.25-350V 100mA output. its got a sink on the output to keep it stable at all load conditions.
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The 723 takes very little current to operate, so the MJE340 dissipates very little,esspecially operating above 24V , but it makes a huge difference in PSRR, brings the total output noise from 20uV to 2uV so I dont see any issues at all.
The late Roger Modjeski, founder of RAM TUBES had an interesting insight into the 723. Here is a reply on a post concerning the background of the 723. He used the 723 in His infamous RM-4 all tube MC headamp.
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Sometimes less is more, and i really like the schematic, but the ECF80 really doesn't need to be there in my opinion.
What do you think about the below schematic?
I added short circuit protection for the speedup capacitor as per tektronix.
What do you think about the below schematic?
I added short circuit protection for the speedup capacitor as per tektronix.
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I have about 60 or so 6CB6 tubes in my stash, so I thought why not use it to control the pass tube, it doesnt have much gain in triode mode, but gives me a gain of 1000 or more, operating with about 75V on the screen grid, I breadboarded this setup driving a 6L6 and both the reference voltage and feedback voltage are dead on the same, 7.25VDC!!
