Question on using glow tubes (v-regs)

[andyjevans]

I'm trying out some glow tubes for the first time. In this instance a 0A2. I have, after a 47uF capacitor:
Vin = 200vDC
Vout = 163vDC
R series = 3.3k

Should I be getting 150v out, as this part is a 150v reg? I did the series resistor calcs from this site:
http://www.tpub.com/content/neets/14178/css/14178_148.htm

(incidentally I think there's a typo in the equation at the bottom of the page which reads 60 volts over 22.5mA - should be over 122.5ma I think)

I haven't terminated the glow tube with a resistor - I guess I should try that next. The load is 2.5mA which at 150v is 60k.

Am I doing anything wrong here? Is the glow tube failing to strike properly at the available 200v?

 

[andyjevans]

Spent a little time on this and phoned a friend, and problem solved. I put a .056 teflon cap and 60k resistor across the output and voltage went down to 160. However, tried another glow tube and it was exactly 150v. Obviously the tolerance of manufacture is not that tight.

I was recommended to try a current sink instead of the series resistor - that's supposed to be a step up in quality and quietness. Looks like glow tubes are go!

Any other users with further suggestions? Andy

 

[zarniwoop]

hey, im not an expert on these things, but i was thinking about trying them in a project. You say your load is 2.5 mA. The spec. says 5mA is the min. current... so that may be an issue. I guess you could just bleed a little more current through a resistor. let us know how it works out!

 

[pengboon]

5mA is min current through the gas tube regulator. Theoretically, your load can have any current, as long as you give the gas tube the min of 5mA, of course less than it's max too... 🙂