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Re: bought caps
From: Robert W. Stephens[SMTP:rwstephens-at-headwaters-dot-com]
Reply To: rwstephens-at-headwaters-dot-com
Sent: Monday, November 10, 1997 11:18 AM
To: Tesla List
Subject: Re: bought caps
>
> From: Matt Mills[SMTP:megavolt-at-usa-dot-net]
> Reply To: Matt Mills
> Sent: Monday, November 10, 1997 5:47 AM
> To: Tesla List
> Subject: bought caps
>
> Hi,
> Managed to get hold of 5x 0.0005uF 5000v AC/7000VDC caps the other day
> for free, i suppose their values are too low but if anyone knows
> anyway for me to use them in a TC any help would be appreciated. They
> are made by sangamo and are MICA porcelain caps. They are rated at
> about 10A.
>
> Also most TC programs work out the cap needed for primary circuit
> mine says for a 13kv/60ma tranny i need a 0.0147uf cap. but many times
> I read about ppl adding more capacitance or changing theirs, so is
> this not a fixed number or is this just the optimum for this supply?
>
>
> Matt. mailto:megavolt-at-usa-dot-net
>
>
Matt,
Those caps sound fine for a very low power vac-tube TC if you place 4
or all 5 in parallel for the tank circuit cap (0.002+ mfd is a good
practical value for such a TC circuit). Their voltage rating is
somewhat low however so your AC RMS from the
plate transformer should not exceed about 1500 volts though which means a
typical microwave oven transformer (~2000-2100 V) would likely blow
them up. Several 811-A triodes would be a good choice to use at 1500
volts. You could also use 805 triodes which are each approximately
the equivalent of two 811A tubes power wise. Since your caps are all going
in parallel the current capability of the entire bank will be increased.
You could actually parallel quite a number of these tubes if you have a beefy
enough power transformer. You could use a microwave oven transformer if you
reduce the voltage to the primary to about 75% with a variac or fixed
transformer.
rwstephens