Re: Here comes the SCR based coil
I have used a small ferrite transformar from in a colour TV set to trig
an scr. Some will work, some wont. also could consider using a
Transformer from old switchmode power supply ( these are designed for
pulsing), or perhaps a wideband 600R line isolating tranny. Also maybe a
good idea to connect a diode across the tranny in opp. polarity to scr's
gate to protect from reverse transients
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>Date: Wed, 13 Jan 1999 21:25:41 -0700
>Subject: Re: Here comes the SCR based coil
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>From: Tesla List <tesla-at-pupman-dot-com>
>Original Poster: Eddie Burwell <eburwell-at-HIWAAY-dot-net>
>At 06:53 PM 1/11/99 -0700, you wrote:
>>Original Poster: "Bill the arcstarter" <arcstarter-at-hotmail-dot-com>
>>Where'd you get the SCR gate trigger transformer? :)
>Mine were surplus from a motor drive circuit. I took the core and wound
>own. Some ferrite toroids like line noise filters may work. Just make
>they don't saturate before you have completely turned the gate on.
>Check out http://www.mag-inc-dot-com/
>I couldn't tell you what to get yet but I'm sure they would have it.
>>I suppose all coilers need is a supply of primary amp*turns at the
>>appropriate excitation frequency...
>>How fast will your circuit run at this point? What sort of output do
>About 500pps max right now. I have been fighting some problem and
>the hard way about magnafier output transformers. It has been difacult
>me to design a transformer with high coupling low inductance and a
>step up ratio. My most succesful transformer so far has been an 8" pipe
>wound with 180 turns of 4 mill poly and 1/2"x2mill copper tape. The
>was one turn of a 3" copper strap. With this setup I could get 8"
>Kind of dissapointing. Some calculations based on the ESR of the
>tell me that 180 turns is too many for a good impedence match. I cut
>the turns to no avail. The transformer by it self could produce 1.5"
>which tells me there is some loss going on somewhere since with 1KV in
>theoretically could have 180K out. So with a little head scratching I
>realized that loading on the secondary will produce loading on the
>and thus more loss in the parasitics of the circuit. So I think I need
>increase the L in the primary so that the parasitics are less
>also need to tighten up my wiring to minimize the parasitics.
> The problem with increasing the L is that the primary resonant
>can get low pretty quick! Especially with 2.5-30uF on the primary. I
>like 20-40Khz! I think that is the route I'm going to take. I have
>30lbs of #25 and maybe 10lbs of #14 and #16. I need to come up with a
>resonator (third coil) in this frequency range. At first I was thinking
>using a short squat coil to get a large inductance. Then I realized
>self C is the bane of a maggie although at these frequencies it won't
>significant. Any thoughts on this are more than welcome.
>>Since the current pulse is such a step (as opposed to a sinewave)
>>implies that substantial energy will be at frequencies far away from
>>the secondary's self-resonant frequency. I'm not sure there's
>>which can be done about that in your design. This may be the limiting
>>factor in terms of net arc length output!
>The BIG ??? diode in my schematic allows ringing. I'll see if I can
>waveform on my website.
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