From: firstname.lastname@example.org (N. Thornton)
Subject: Re: Spark gap q
Date: 13 Nov 2002 12:55:36 -0800
NNTP-Posting-Date: 13 Nov 2002 20:55:37 GMT
email@example.com (John Crighton) wrote in message news:<firstname.lastname@example.org>...
> On 12 Nov 2002 10:07:43 -0800, email@example.com (N. Thornton) wrote:
Thanks for the replies.
> Is there any combination of material / curent etc that produces a
> fixed spacing spark gap that doesn't burn at all, i.e. would be very
> long lasting?
I am thinking in terms of miniature spark gaps, run at very small
currents, more signal than power.
> Spark gap design is still something of
>an art. What voltage, current, rep rate, etc?
V very low, very narrow gap. Below 20v.
Current ditto, far below an amp.
Rep. rate 100Hz. faster rep rates would be attempted later, but aren't
Its difficult to be more precise at this point.
> What environment (air, pressurized gas, vacuum)?
All those are an option. Naturally open air would be simpler.
> Can you do active cooling (air-blown gap or hollow electrodes
> with flowing water cooling)?
The short answer is no, as I want to miniaturise this. But the powers
involved are very small, so if it will work at all I dont expect
significant cooling to be needed.
I have worked in the past with carbon arcs, and to a lesser extent
spark gaps, and am wondering if a miniature signal level version could
work long enough to need no maintenance... so we're talking 10 years
used maybe an hour or 2 a day.
>is this the sort of spark gap that you are looking for in this old
Thats a monster! :)
>If so, they are just thick rods of mild steel with a small piece of
>tungsten on the end. These rods with tungsten can be bought
>as spare parts at large welding stores. Quite expensive here
>in Australia. There is a man who makes them for $12 a piece
>here in Sydney by silver soldering old tungsten carbide cutting
>tools to the mild steel rod. The solder has to have a high silver
>content , 45% or more. I tried the the 2% silver solder and it was
>no good. There is a special flux also that has to asked for at
>the welding shop to suit the tungsten carbide. I was told the
>general purpose flux for silver solder is not as good for tungsten
>carbide as the special stuff.
>Since I picked up the complete arc starter for $10 I did not
>follow up on making my own spark gaps.
>Hope this info is of some use.
Yes thankyou, that gives me pointers on materials and possible methods
for miniatures. I hadn't seen those materials used before, at least
At this point I dont know how a very low current arc will behave
differently to power arcs: I'm pretty much at the beginning on this
one, investigation if its a possibility. Thanks,