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Re: Ignitron Tubes
Tesla List wrote:
>
> >From baronin-at-post.crc.cra-dot-com.auTue Jul 2 13:15:34 1996
> Date: Tue, 02 Jul 96 17:16:00 EST
> From: "Baroni, Nicholas" <baronin-at-post.crc.cra-dot-com.au>
> To: engtes <tesla-at-pupman-dot-com>
> Subject: Ignitron Tubes
>
> >From what little I understand about ignitrons, they are
> a bit like a controllable mercury arc rectifier - ie
> what SCR's are to diodes.
>
> Could you use two of them, one between the transformer
> and the pulse cap and the other between the cap and TC
> primary, ie
> Ignitron 1 Ignitron 2
> 3|E-------(===)----------(===)-----3
> 3|E | | | 3
> 3|E gate? --- gate? 3 TC Primary
> 3|E --- 3
> 3|E | 3
> 3|E--------------------------------3
>
> and control the ignitrons so that you charge the cap
> up to peak voltage on one half cycle (at 50/60 Hz it
> should block and act as a 1/2 wave rectifier.
>
> Once the voltage has fallen, fire the second tube to
> connect the primary across the cap. The oscillations
> would then continue until there is no energy in the
> primary circuit. With all the sparks, the oscillations
> should damp quickly and avoid latching in the Low
> Frequency HT.
>
> If they are slow to de ionise, won't they still
> conduct? May want to add another tube across the
> second back to front and trigger them together.
>
> Then fire the first ignitron again and start the
> cycle again.
>
> I realise that as far as power throughput is
> concerned, this is a dog of an idea only charging
> up every other half cycle. I also don't know the
> details of the trigger circuitry, it is easy
> enough to detect a zero crossing but I don't know
> enough to drive the tubes.
>
> Any comments? Is an Ignitron functionally equivalent
> to a SCR/Thyristor or do I have a misconception
> somewhere?
>
> Nick B.
Nick,
They are exact replicas of SCRs but they can't shut down quickly so make
terrible replacements for a gap.
Richard Hull, TCBOR