Beware that "large value" capacitors often have higher impedances at higher
frequencies, so use whatever value you want for the high value, but put a
100 pf and maybe a .01 uf in parallel to shunt the higher frequencies.
By the way, I just yesterday ran across some old line filter assemblies that
could possibly help - they are 2 amp units - I put them on ebay to get rid
of them - if you are interested, search for a listing with this title
fragment " 2 amp Quietone line filter Cornell Dubilier IF-54"
-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Bert Hickman
Sent: Friday, January 1, 2016 10:19 AM
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Subject: Re: [TCML] auto coil HV supply
Hi Doug,
The problem is that every time your dimmer TRIAC or SCR fires, the series
capacitor and induction coil primaries generate a high-current, oscillatory
voltage transient that appears across your AC mains. It's inherent in the
operation of this circuit. The larger the series capacitor, the higher the
transient currents and the greater the risk of damage to other devices on
the same circuit.
Under worst case conditions, the series capacitor will be charged to the
previous peak line voltage when the dimmer fires. For 120 volt mains, if the
dimmer fires at a mains voltage peak (170 volts), the fully charged series
capacitor dumps an ADDITIONAL 170 volts through your ignition coil
primaries. A portion of this 340 volt transient appears across the mains,
potentially wreaking havoc to other devices connected to the same circuit.
Depending on the primary inductance of your ignition coils, a comparatively
high frequency oscillatory current (500 - 2 kHz) with peak current of 10-30
amps will flow through the mains wires. If there is significant inductance
or resistance in the supply path between your breaker box and driver
circuit, these repetitive transients can damage sensitive electronic
equipment on the same circuit. Powering the driver from a line protector
outlet strip may even cause catastrophic failure of its internal transient
suppressors.
One "brute-force" fix might be to connect a higher-value motor-run capacitor
across the mains at your ignition coil driver. The mains shunt capacitor
will help to bypass the higher-frequency currents, thereby reducing voltage
transients seen by other devices across the AC mains.
I'd recommend using a mains capacitor that is at least 2 - 3X the size of
your existing capacitor to tame the "nasties" originating from your driver.
Bert
--
Bert Hickman
Stoneridge Engineering, LLC
http://www.capturedlightning.com
***********************************************************************
World's source for "Captured Lightning" Lichtenberg Figure sculptures,
magnetically "shrunken" coins, and scarce/out of print technical books
***********************************************************************
doug wrote:
> Hi Ed; Thank you for your reply and thanks also to Dave and Miles for
> your replies. What I have is a dual ignition coil, dimmer switch and
> 24uf/370v motor run Cap setup and this thing is really "HOT'! I didn't
> realize how "HOT' until I powered a 12 inch lightning screen with a 5
> inch center plate on it. I had used the HV supply with a Jacobs ladder
> and other stuff with no problems. When I powered the lightning screen
> with it, which is really just a lop-sided Capacitor, it really back
> fired! took out a fluorescent ballast on the same circuit and fried the
> mains outlet it was plugged into! Luckily the mains outlet was remote
> from the wall outlet, like an outlet box with a cord which was plugged
> to the wall.
> I tried to find something on [Corcoms] as some suggested but could
> nothing. What I was hoping was that someone could supply me with a
> diagram with component values, that I could build, on the order of the
> terry filter.
> Thank you all; Doug
>
> -----Original Message----- From: Ed
> Sent: Thursday, December 31, 2015 10:15 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] auto coil HV supply
>
> What kind of coil driver circuit are you thinking of? Some will glitch
> the line and some won't. With the capacitor discharge light
> dimmer/thyristor approach a normal EMI line filter can raise the
> impedance at the coil end so much that the peak current is limited and
> sparks are cut way down.
>
> On 12/31/2015 12:07 PM, doug wrote:
>> Hello; Can any one advise me on some kind of filter or device I can
>> build or buy that will stop any HV spikes from an automobile ignition
>> coil high voltage supply from backing into the mains?
>> Doug J
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
>>
>
> _______________________________________________
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> _______________________________________________
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>
>
>
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