voltage regulator tubes

[dgta]

...but was simply wondering if one of these things would work at all with the anode attached to a voltage source and the cathode attached to a plate. In this case an EL84. No grounding other than the cathode of the EL84 or any tube for that matter.

Yes it would conduct electricity, this was answered already. Whether this can be considered "it works" depends on what it is you are trying to accomplish.

Of course, enough voltage would be applied to the anode. I was wondering if the thing would conduct the voltage at all in a series connection AND if you supplied it with 250 volts would 175 volts be the result .

Yes it would do that subject to the current limitations stated. So if your EL84 is running at between 10 and 20mA at all times, yes. If not, then it won't.

...or would a VR75 still only allow 75 volts to pass (until it ceases to work)

Voltage doesn't pass through a device. Current does.

One would have to think if you could get the voltage to jump across that gaseous gap, even though this in itself would produce noise, that it would leave most of the noise from the line in the gas.

No there is no basis for thinking that. There is no known material, including plasma, that magically removes noise from a signal. Just the opposite.

Not sure how much regulation would ensue.

None

If you are curious about how things work, I highly recommend a beginning course in electronics at your local community college or university_

 

[bayermar]

Me personally? I'd put a 5 kΩ resistor on that regulator and not use its regulated voltage directly. Instead, run it to the base of a HV transistor in series with the HV leg, to deliver around 0.9 volts less than the reg-tube nearly-constant-current stable volts… [...]
[goat hides behind a tree, expecting fusilage of eggs, tomatoes and last year's sushi…]

GoatGuy

Hi GoatGuy,
No need to hide behind the tree. The only thing I am throwing is a sketch (of a schematic). Something along that line?
The right version with CCS supplying around 10mA (sorry did not find a correct symbol).

To everyone else: It's nice to be back after a couple of years (must have been almost 10) and seeing some of the usual crowd still around (and some sadly missed 🙁 ).

Cheers,
Martin
🙂

 

[SemperFi]

Mr Kolbrek did some nice measurements and experiments if ya look here:
Testing Power Supplies

Scroll to the VR tube part. Interesting fix he does to get a flat impedance over frequency, adding a resistor in series with the bypass cap, thereby able to increase cap value a bit.

(Kolbrek's mod was linked to in the first page of this thread)

 

[bayermar]

Interesting read, indeed. Thanks!

The link on the first page seems to be dead.

Cheers,
Martin

 

[kd1yt]

VR tubes actually generate small amounts of random noise. Easy to knock it out with proper circuit design, But the idea that they magically subtract noise is baloney. I like VR tubes. But they are not magic.

 

[SemperFi]

Well VR tubes are good for getting a voltage within a decent range, and they make great indicators VS a fugly LED.
How about this Martin, attached schem?

Ref Kolbrek, the C can be increased if used w the series resistor, I'd try 10uF but might be conservative and use 10ohm or higher for R. A flat impedance of 10-20ohms over a wide frequency is better than a low impedance with rising peaks in the hundreds of ohms.

 

[bayermar]

Hi SemperFi,

yes, that looks good. VR tubes look great, but I have to admit that I have a soft spot for LEDs as well.
Indeed, higher output impedance might not be such a problem if there is less variation over a large range of frequencies. Especially if the load is reasonably constant.
If you want to have lower output impedance, you would probably go "all silicon" anyway. 😀
The cap on the base of the pass transistor is for soft start?

Best,
Martin

 

[SemperFi]

The cap after the base resistor creates a capacitance multiplier function with the R, C, and NPN.
The Capacitance Multiplier | audioXpress

 

[bayermar]

OK. Got it.
Thanks!

Martin