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Spark gaps
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From: Zuma [SMTP:mwise-at-ns.sosis-dot-com]
Sent: Thursday, February 19, 1998 3:42 AM
To: Tesla List
Subject: Re: Spark gaps
Tesla List wrote:
>
> ----------
> From: Justin Oliver [SMTP:joelec1-at-ozemail-dot-com.au]
> Sent: Wednesday, February 18, 1998 11:02 PM
> To: tesla-at-pupman-dot-com
> Subject: Spark gaps
>
> I am having trouble with my spark gap. My xfrmr is a 10Kv 10ma ignition and
> I put the two leads together to see how big a spark I could get and it was
> about 1cm. I then made my gap - I got two screws and cut the heads off them
> leaving me with about an inch of screw with thread and 1/2 inch without. I
> then cut two bits of brass bar about 1/4 inch long, drilled a hole through
> the middla and silver solded the bare end of the screw through it with about
> 1/8 inch of the screw end sticking out. I drilled a hole through two L
> shaped bits of steel and screwed the terminals into the holes.
> | |||| |||| |
> *****|*****8888|||88 88|||8888*****|
> | |||| |||| |
> | |
> | |
> ____________| |_______________
> Legend:
> * = Screw with thread
> 8 = Screw without thread
> ||||
> Bit shaped like ||| = Brass heatsink
> ||||
> Using this setup I can only get a spark 2mm long and it sounds like a swarm
> of bees. The spark is all purple like it is giving off ultraviolet. I have
> been told a spark gap works better with an airflow going through it so I put
> about 75 psi through it and the spark turned white and hissed like a snake
> though I could still only get continous sparks at 2mm with short bursts at
> 3mm. Why can I get a 1cm spark from the terminals of the xfrmr yet using my
> gap I can only get 2mm spark. Will this change when I finish my coil and
> there is a capacitor in place? Also, I was told that you can change the
> frequency of a primary by changing the distance of the spark gap because the
> capacitor discharges faster. Is this true?
>
> Justin Oliver
When you tested how long of an arc you could get between the two leads,
Did you touch the the leads together and pull them apart? If so that's
why you may have longer arcs between the leads. In the gap it is set at
a distance to where it has to jump a set amount of space making it a
little harder to jump an arc. Any way back to your situation. When you
give it the recommended capacitance it will more readily jump the gap
better. For a 10kv transformer you should have a total gap setting of
between .075"-.125" but no more than .15". Also I would highly recommend
you build a series cylindrical gap. There are plans availible for this
type of gap and it works 100% better in my opinion.
Chris