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Common Mode DC Power Filter
Hi Gary

How about a circuit description here for those who do not use youtube?

Have fun
(05-29-2023, 10:40 AM)K O'Connor Wrote: Hi Gary

How about a circuit description here for those who do not use youtube?

Have fun

this circuit null the A/C ripple voltage, but also acts as a passive voltage regulator. Bear in mind, this is all done with injecting an error correction signal, into the back end of the DC rectifier. Since there are no active devices, no transistors, no "IC linear regulators", this approach does not generate any of the waste heat, compared to it's active counter parts.....

Now begs the question , would I use this filter inside my own amplifier builds ? All good questions , given Surface Amplifier already has A/C ripple rejection, as a side effect of using a vacuum tube for it's input Dynamic Load SRPP gain stage. An effect few class A amplifiers can achieve, due to the air gap inside a vacuum tube , mostly......

i was thinking , for example , a more painless way to generate a clean 5 volts for filament power for a 300B.

I expect a few parts from another vendor, a few power rheostats, to make my circuit fully operational. Of course I will share all of that . If successful, the next step would be to replace them with power transistors, to handle higher load voltages and load currents. I'll have to see how that would play out...
Hi Gary

Show us a schematic when you have a working circuit.

Have fun
.... it is a working circuit, and this one reason why I normally don't post schematics on internet forums.
.. also, as a side note, what I meant to say was, I was first, i believe, to install led bias inside a Valve Junior ; not the first to ever do it.
Just one more reason why all this internet forums and all this "management-by-remote-control", just doesn't work...

Common Mode Power Filter / with 0.5 ampere load

In this video, I reduced the load current to 0.5 amperes, to be more in line with the current rating of the power transformer I am using.
Also, I emphasize one of the design goals of this unit to be voltage output adjustable. Reason being, I will go to some effort to
run my vacuum tube filaments right at 6.0 volts. Yes, the rating is 6.3, and I have read where others run filaments up to 7.0 volts.
I believe if filaments allowed to run at 7 volts or higher, those tube probably not live long. I run my filaments a little on the
cool side, and in the last 15 years, my equipment remains fully operational.

So, I did this video to show a response to messages, asking for both the adjustment in output voltage, and the ripple rejection.
Then, it occurred to me, why not run this same type of rig on a 600 volt / 200 milliampere plate power supply ?
Is this not the goal to have very low a/c ripple on the plate of a Single Ended Power Stage ? If so, it would solve a lot of
problems. As such, I would still consider building an external power amplifier for Surface, and using Surface as a preamp.
I don't want to build an audio stereo power amplifier using the 300b. Those tubes about $200 dollars each, and my ears just
not worth that kind of money. But, I would run a stereo power amp using a pair 6L6 power tubes, and I know Surface would be able
to fully drive a 6L6 with the plates running at 600 volts. Yes I know this level is higher than what the data sheet recommends,
but I am able to keep the plate current in check with combination bias and Electronic Power braking on the screen grid.

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