fool-proof standby switch for tube gear.....if you believe in such things

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emrr

Well-known member
Joined
Apr 12, 2006
Messages
8,525
Location
NC, USA
I didn't make this one up, think I saw it in Glass Audio a dozen years back.  Two power switches, doesn't matter which you throw first, you're in standby mode until you throw the second.  Wait, I guess the not-foolproof part would be not turning them both back off. 

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One project of mine that I considered critical has an "automatic" standby mode.

When PSU switch is turned on, initially only "slow turn on" heaters are started. they will creep up to 6.3VDC in 5-10 seconds. When they pass somewhere around the 5VDC point, a safety relay is finally turned on. This relay initially prevents B+ VAC part from entering the B+ rectifier and filters at all. B+ works only if heaters are online.

If heater PSU circuit dies for whatever reason, The lone B+ won't kill all the tubes either.
 
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