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Re: Gauges
Posted By: Romarrk In Response To: Re: Gauges (Romarrk)
Date: Sunday, 31 March 2013, at 1:10 a.m.
> Mark, may be you are right because Hastings
> tubes are more tricky to run than old-school
> one I use.> They can use only pure AC for drive because
> thermocouples are mixed with heater. That
> means more complex circuit that plain LM317
> I use. Still not rocket science though.Well, seems that western TC gauge tubes 531 and 6343 are intended to use DC heater like one I use. http://www.belljar.net/tcgauge.htm
Actual circiut can be even simpler than shown at Belljar, avoiding the preamp, since many modern cheap multimeters can reliably measure 10-15mV directly.
That brings circut complexity not only to "backyard electronics" but down to "bombarder+choke" level which every 'Neoniste' (with brain not irreversible damaged by mercury vapor ;) shall understand.
Once calibrated against ultimate vacuum, it will make great cheap tool to check if manifold and pumps are ok. Even when pumping down, micron gauge immediately shows the tube is leaky, without resorting to spark tester.
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