• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

HV delay switch

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Hey Folks,

Can I install a switch between the HV secondaries before the rectifier to let the rectifier warm-up before applying the high voltage? Ive seen some scheme that use those but I cannot find a DPST OR SPST switch that goes above 250v in rating. Do you guys know where to get one?
 
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Delaying AC power to the rectifier plates is usually unnecessary if you're using a standard vacuum type. If mercury vapor, then yes it's necessary to delay. If you just want to save a little wear and tear on the tube, then you could put SS diodes in series with the plates and the transformer winding. But if you insist on a switch, then it's best to use a relay. Either manually turn it on/off with a smaller switch, or use a seperate or internal time delay circuit. The contacts will withstand hundreds of volts. I'd look on eBay for the better prices.
 

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Thanks for the input fellas. I was planning on subbing an 83 mv rectifier in place of a 5u4g in my se amp without resorting to a separate filament transformer. The power supply have clc arrangement and I was thinking of just adjusting the first cap to get the right voltage if I use the 83.

Without a separate filament transformer for the 83, where is the best place to put a switch to let its filament warm-up before applying hv? I can't think of a place where to put them but before the rectifier ,n I dnt want to deal with relays.

I think its time to find a 5vct filament transformer.
 
With a MV tube you don´t want to switch the DC.

Switching DC is a more complicated task since relays cope with less DC then AC voltage.

Switch the AC going into the tube !
That was our point in that thread. However, there was a solution found to switch DC that seems like it'd work. Someone here may (or may not) find it useful. I've always thought "Never switch DC" and was surprised.
 
That was our point in that thread. However, there was a solution found to switch DC that seems like it'd work. Someone here may (or may not) find it useful. I've always thought "Never switch DC" and was surprised.

I´ll better read up then, the only thing working for dc i know of is the vacuum switches i´ve "borrowed" from work and they cost an arm and a leg....
 
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