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Old 27th March 2007, 06:51 AM   #1
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Default Voltage Regulator Tubes

I have been given a bunch of voltage regulators -- 0D3, 0A3, 0B2, maybe a few others -- and have no real sense of how to use them or whether they are worth the effort. Anyone have any good links or suggested reading?
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Old 27th March 2007, 07:51 AM   #2
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This is the PSU for my line stage, with 0D3s:
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Old 27th March 2007, 11:08 AM   #3
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Helpful applications are in the data sheets:


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Old 27th March 2007, 08:07 PM   #4
Sheldon is offline Sheldon  United States
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They are actually pretty easy to use - only a few considerations:

1. Need a little extra voltage above the operating point to light them off (depends on the type).

2. Use a current limiting resistor or current regulator to stay under the maximum current limit (the short term limit is well above the steady state limit) when the downstream stuff is not yet drawing current.

3. The general load recommendation I've seen, is that the load current should be within about half of the steady state limit, and the steady state current through the tube should be around half of the continuous maximum.

4. With series regs., you'll often see a high value resistor (200k or so) from the supply to the series connection between tubes. This helps light off the lower tube.

5. Keep the capacitance across each tube less than 100nF (even less to be on the safe side).

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Old 27th March 2007, 08:19 PM   #5
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Default Re: Voltage Regulator Tubes

Originally posted by dsavitsk
I have been given a bunch of voltage regulators -- 0D3, 0A3, 0B2, maybe a few others -- and have no real sense of how to use them or whether they are worth the effort. Anyone have any good links or suggested reading?
However, main functionality is not so significant (Zeners are available) as their nice look, when they indicate presence of a plate voltage and it's variations:


Click the image to open in full size.
The Devil is not so terrible as his math model is!
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Old 27th March 2007, 10:01 PM   #6
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http://www.tpub.com/content/neets/14.../14178_148.htm theory and calcs

How do you use a 0D3 regulator?

I've archived the following from the Net - not sure who the original authors were.

There is no "maxiumum input" as such. The tubes act like a zener, so whatever voltage you put into it, 150V will be dropped across the tube. That's why you need a dropper resistor, the rest of the voltage is dropped across is and this sets the current thorugh the tube. Without the resistor, even if you put 170V into it, without a resistor, it would blow up. You need to calculate the dropper resistor to drop the remaining voltage and give you a sensible current (5mA - 30mA for 0A2) through the tube. You also need to leave room for the current swing of the circuit you're powering. In theory, you could run them of kilovolts if you like, you would just need a *very* big resistor.Cheers, Pete P.S. The resistor can be replaced by a CCS.

Voltage Regulator (or VR) valves are ingenious devices designed to maintain a constant voltage across their terminals over a range of currents.Such valves have a cold cathode and contain gases at low pressure rather than the conventional high vacuum normally used in amplifying valves. The internal gasses are deliberately chosen to ionise (conduct) at a particular predefined voltage.
They work very well just like a zener.And they glow. Unlike mercury tubes they don't need to wait for the filament to light up, since they ain't got no filament. No mercury, either, just harmless argon. There's *neon* ones, too, which glow a cute pinkish or orange, like 0A3. Just don't force them to draw too much current (they only need a few ma to light up). Colour is entirely due to gas composition. Voltage drop is due to a combination of gas composition and cathode material. The level of intensity of glow is proportional to discharge current.
OD3 and 0A2(150V) are pink / lilac.
0C3 and 0B2 (105V) are also pink as far as I can tell (my 0C3s are almost entirely gettered)
I understand that 0B3 (90V) is a purple/indigo. Prettiest of the bunch IMO. thought ususally gettered into near invisibility.
0A3 and 0C2 (75V) are orange.
The confusion over colours possibly comes from the change in coding between the 0*3 (octal)and 0*2 (7-pin) series, where one went A to D with later letter higher voltage and the other went the other way. In addition there is the confusion added by the 85 Volt reference (low current high stability) 0E3 (octal) and 0G3 (7 pin).
Type OpV StrikeV min/max mA regV Pinout
0C2 75 115 (105) 5-30 4.5 7pin
0A3 75 105 5-40 6.5 Octal
0B3 90 110 Octal
0B2 105 133 (115) 5-30 4 7pin
0C3 105 133 (115) 5-40 4 Octal
0C3A " 127 " "
0A2 150 185 5-30 6 7pin
0D3 150 185 (160) 5-40 5.5
0D3A " 180 " "
0A4 Octal
0A5 7pin
Voltage Regulator 0A2 7 pin small
Maximum Supply Voltage ........................ 185 V
Regulated Voltage ............................. 150 V
Maximum Current ............................... 30 mA
Minimum Current ............................... 5 mA
Regulation (Min to Max Current) ............... 2 V
Voltage Regulator 0D3 octal
Maximum Supply Voltage ........................ 185 V
Regulated Voltage ............................. 150 V
Maximum Current ............................... 40 mA
Minimum Current ............................... 5 mA
Regulation (Min to Max Current) ............... 4 V

The 0A2, OB2, 0C2 tubes are all 7 pin minature base. The cathode of each is connected to pins 2,4,7. The plate is connected to 1 and 5. Pins 3 and 6 are listed as "internally connected" so don't connect anything to those pins.
The 0A3(a), 0C3(a) and 0D3(a) are all 8 pin octal bases, with a jumper between 3 and 7, often used to protect downstream electronics in case the regulator wasn't inserted, pin 5 as the plate, and pin 2 as cathode. The diagram snows pins 1 and 8 not connected.
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