WAY OT! Re: [SEL] Early Switchboard Meters and Switchgear

[Michael P. Koryciak]

Not zeners.Substantial P.I.V. (Peak Inverse[reverse] Voltage) standard 
silicon diodes.
Used for D.C....like a car's coil making a spark when it's magnetic 
field collapses.Same thing happens with all inductive 
[Transformer,Coil,Relay, etc.] circuitry.


John Culp wrote:

> Curt, I don't fool with that newfangled solid state stuff much at all. 
> I wasn't the one who brought up snubber diodes, I pointed out that 
> they were a silicon analog of a tube. If what I'm working on doesn't 
> have tubes in it, I feel like a stranger in a strange land! RC 
> circuits do work well for voltage spike protection on tube amp output 
> circuits, as does a simple resistor across the secondary in the ratio 
> of, say, 20/1 to the load resistance. Spoils the Q of the transformer 
> just enough to keep it from frying things if the speaker's left 
> unconnected and a transient gets into the amp input. An RC series 
> across the transformer's primary serves the dual purpose of also 
> shaping the tone, filtering off highs. It's been called a "conjunctive 
> filter." It's not quite a simple low pass filter, as it is in parallel 
> with the inductance of the transformer primary, so there's an LC 
> resonance also involved.
>
> Yeah, 5Y3GTs are a good old rectifier tube! I've got a big old radio 
> that uses that. Been in the family since 1951. Every once in a while I 
> have to fix it. :-)
>
> John
>
> On Jul 18, 2005, at 2:17 PM, Curt wrote:
>
>> John,
>> Since you have changed from DC circuits to AC circuits,  I gotta ask, 
>> why use a solid state device for energy absorption when a simple 
>> rugged RC circuit does well?
>> I've not seen these quenching/spike diodes you mention used anywhere 
>> on contacts or coils. Are these simply zenors?
>> On your tubes.....5Y3GT 's? I think I've still got a few of those.....
>> Curt Holland
>> Gastonia, NC
>
>
>
> John Culp
> Bristol, Tennessee, USA
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