|
Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
|
Thread Tools |
15th Mar 2019, 1:07 am | #1 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Series connected stabilizer valves: questions
I have three 'known-good' 0B2 stabilizer valves. The 0B2 has a stab. voltage of 85 v. ± 1v. depending on its current and a striking voltage of about 130 v.
The idea is to connect three 0B2 valves in series to produce a stabilized voltage of 255 v. (255 = 85 x 3) from a 350 v. input voltage. I used 220 kΩ resistors from the 350 v. to the two 'lower' valves to meet the striking voltage requirement and a 4k7 Ω resistor from the 350 v. to the first 0B2. Yet configured as a '255 v. stabilizer', the current drawn from the 350 v. supply is far less than my calculations predicted - so as a '255 v. stabilizer', it doesn't work. The wiring is correct; my arithmetic makes sense - so what part/s of all this do I have wrong or do not understand? All replies will be appreciated. Al. |
15th Mar 2019, 2:34 am | #2 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 898
|
Re: Series connected stabilizer valves: questions
The 0B2 is 108V nominal, not 85V - what datasheet are you looking at?
|
15th Mar 2019, 7:27 am | #3 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,637
|
Re: Series connected stabilizer valves: questions
The calculation for these valves is about 5mA for each valve + the load current from memory, so 220k for the lower valves is too much I think, each lower valve is only getting around 0.75mA or the middle valve is getting around 1.5mA, the lower one nothing.
Andy.
__________________
Curiosity hasn't killed this cat...so far. |
15th Mar 2019, 7:34 am | #4 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
|
Re: Series connected stabilizer valves: questions
Hi Al, I may have some 280 or so volt stabilisers, a bit bigger than the OB2 valve though; but may handle a greater current.
Ed |
15th Mar 2019, 10:33 am | #5 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
|
Re: Series connected stabilizer valves: questions
Skywave,
First thought, apart from the obvious that they are 105 volt regulators, is do they all fully light when powered? You probably do not have enough voltage headroom to start with. Getting series regulators to strike and pass burning current can be a bit of an art, especially three in series... You do not show your calculations so what current do the pull from your supply and what were you expecting? Working on what you have and assuming they are all 'lit', 350 volts in and 315 volts 'regulated' out, so 35 volts drop, using your 4.7k limit resistor should see about 7.5mA? It might be necessary to actually add a small load to make it stable. A 100k, 1 watt resistor will load it by about 3mA. So questions are, what stabilised voltage do you want and what current does it need to be? Alan
__________________
Never Leave Well Enough Alone... |
15th Mar 2019, 11:22 am | #6 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
|
Re: Series connected stabilizer valves: questions
There are circuits with diodes as well as resistors which put the regulators in parallel for firing and then in series for running. However, your first job is to use 85V regulators instead of 0B2.
|
15th Mar 2019, 1:44 pm | #7 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
Re: Series connected stabilizer valves: questions
0B2 data sheets with graph/formula etc:
http://www.mif.pg.gda.pl/homepages/f.../127/0/0B2.pdf Lawrence. |
15th Mar 2019, 2:23 pm | #8 | |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Re: Series connected stabilizer valves: questions
Quote:
Apologies to all who were similarly confused. Al. |
|
15th Mar 2019, 5:09 pm | #9 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,924
|
Re: Series connected stabilizer valves: questions
I might be inclined to go the wimp's way and buy some zeners
B
__________________
Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
15th Mar 2019, 5:25 pm | #10 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Re: Series connected stabilizer valves: questions
Having now reviewed my above thinking, etc. I can now see that that thinking was clearly in error. I really shouldn't do things like this when its very late at night and most of my brain cells have gone to sleep! (Especially with voltages of these magnitudes. ) But enthusiasm being what it is . . . However, with a bit of a re-calc., etc., things are now working as they should.
350 v. in; 1k5 series resistor; 150 kΩ resistor from stabilized rail to anode of 2nd. valve; similarly, 220 kΩ resistor to anode of 3rd. valve. That puts about 1 mA start-up current into each of those two valves to initiate the striking voltage. The voltage across each valve is then as it should be. Current through the valves is approx. 20 mA. On test, Vstab is 322 v. no-load; 320 v. at 20 mA. That is more than adequate for what I have in mind. Al. |
15th Mar 2019, 5:32 pm | #11 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Re: Series connected stabilizer valves: questions
Bazz: using Zener diodes for this application. I ruled that option out on two grounds:
1. Past experience showed that the temp. coefficient of H.V. Zeners seriously degrades the stabilized voltage; 2. I have more N.O.S. 0B2 valves in stock than I am ever going to need. Al. |
15th Mar 2019, 5:49 pm | #12 |
Guest
Posts: n/a
|
Re: Series connected stabilizer valves: questions
Surely you only need the start up resistor to the second valve down, the two in series below have a total breakdown of much less than to 350V in, it can be quite a big resistor too. Or one across any valve.
Last edited by Guest; 15th Mar 2019 at 5:50 pm. Reason: Added another idea |
15th Mar 2019, 6:19 pm | #13 | |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,924
|
Re: Series connected stabilizer valves: questions
Quote:
B
__________________
Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
|
15th Mar 2019, 10:37 pm | #14 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,706
|
Re: Series connected stabilizer valves: questions
What about trying an OA2 & OB2 in series, as used by HP in the 412A Voltmeter to provide 255V.
David |
15th Mar 2019, 10:55 pm | #15 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,527
|
Re: Series connected stabilizer valves: questions
Quote:
To avoid that problem, use a longer string of lower voltage zeners. Distributes the dissipation as well so you can use lower power ones.
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
|
15th Mar 2019, 10:56 pm | #16 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,951
|
Re: Series connected stabilizer valves: questions
Pat Hawker's "Technical Topics" offers this: it also works if replicated across a chain of series-connected glowtubes so each one 'sees' rather more of the supply-voltage until they are all ignited.
|
16th Mar 2019, 12:58 am | #17 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Re: Series connected stabilizer valves: questions
Thanks for the further replies: several ideas there that are new to me.
And on that sub-topic of 'things new', how about this . . . I tested several 0B2 valves - they've been in my possession for decades and are all 'N.O.S'. They all carry the brand name Haltron and are all marked CV1833. All of them - except one - met the published spec. for an 0B2. The one that didn't performed excellently as 115 v. stabilizer. I am not aware of any B7G-based stabilizer valve that has that voltage. Any ideas to explain that? Al. |
16th Mar 2019, 1:08 am | #18 | |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Re: Series connected stabilizer valves: questions
Quote:
The production of that -ve. L.V. rail looked like something new to me - at first. But when it's re-drawn in a 'conventional' style, it then appears to be not new at all. Many have been the times I've struggled to understand cct. diagrams drawn 'American style', which, when 'translated', then become understandable. Al. Last edited by Skywave; 16th Mar 2019 at 1:23 am. Reason: General re-write |
|
16th Mar 2019, 10:04 pm | #19 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,706
|
Re: Series connected stabilizer valves: questions
I guess you wanted 3x108V (324V) instead of 3x85V (255V).
HP often used the 5651A 85.5V reference tube for the voltage regulation with either a valve or transistor based series regulator. The 5651A has a lower current rating than the 0A or 0G series voltage reference tubes. Not sure about the 115V one, the last faulty VR tube I found had a crack from one of the pins, I'm sure it lit up at first but I didn't check the voltage until until another fault occurred, the neon must have slowly escaped or mixed with air as the instrument warmed up. David |
16th Mar 2019, 11:05 pm | #20 | |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,924
|
Re: Series connected stabilizer valves: questions
Quote:
Since my last post I recalled that one PSU I built for my HRO HT used 3 zeners (75V ?) to control a MOSFET, thereby reducing the power level and thermal load on the zeners. B
__________________
Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
|