PHOTOS of my Franceformer and the sparks

Made a 1/4" spark gap... I see sparks... Very exciting...

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Reply to
Ignoramus27736
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That's a neon xfmr. Three of those in series should make a dandy Jacob's ladder! The buzzzzzzzZZZAP noise it makes adds to the fun. With 3 or 4 of them in series, a Jacobs ladder should be able to sustain an arc over an inch long before it goes out at the top and starts again (ZAP) at the bottom.

The nameplate ratings can be confusing. They deliver rated voltage under open circuit conditions, rated current at short or near-short conditions. Once a spark/arc is initiated, voltage drops to about 1KV in a short gap. 1KV is a near short condition for a 30KV xfmr.

A job I once had was designing electronic oil ignition xfmrs, 30KV at

30 mA. They ran at about 30KHz. In normal use the rectified AC wasn't filtered -- but if a filter cap was added, the arc/spark was eery quiet -- just sort of a soft hiss. A Jacob's ladder with that was like the audio was missing.
Reply to
Don Foreman

Dang, so it really is a Franceformer, huh? Looks big enough to be very dangerous.

Reply to
Dave

no no no no no no NO!!!! please don't put them in series. if you do that, you will very likely destroy one or two of them due to breakdown between the primary and secondary - look at it this way, all the primarys are in parallel (you plugged them in, right?), with the secondaries in series, there is around 27KV between the secondary of one transformer and the primary of the one farthest away (electrically). The primary to secondary insulation is designed for a 4.5KV standoff, with some safety factor, you are at 27 - not good, breakdown very probable. AND, if you are unlucky, you will find that the secondaries are center tapped with the center tap connected to the case.

Why risk good transformers. with 9KV and a jacob's ladder you start at about 1/4 inch at the bottom, you should be able to get an easy inch or three at the top - the plasma conducts much better than air.

Find one of the tesla coiling groups before you destroy these things, please.

bill n

Reply to
william_b_noble

Yeah, Ha ha, I thought the name was a typo/joke too.

Reply to
xray

Sounds interesting. I have 13 of them today. Maybe I will get more tomorrow. I forgot to pay for all the stuff I got today (and the owner forgot to ask me for money) and need to go there tomorrow to pay anyway.

Sorry, I digress.

I am confused by different statements made by different posters. Some say that they cannot be set in sequence because they are center tapped to ground. I am not so sure, since they can be mounted in isolation. Who to believe?

Yes. I just tried something interesting. I tried blowing at it. It made some big arcs and a corona discharge. Tomorrow, I may try to blow argon at it from my tig welder.

Very nice.

Well, sure, that's what constant current stands for, more or less.

The nameplate does not actually say what the output current is, AC, DC, HF, etc. I think that midpoint grounding pretty much implies AC. Not sure if it is 60 Hz or HF. My guess is that it is 60 Hz, both from the buzzing sound as well as the weight of this franceformer.

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Reply to
Ignoramus27736

This does make sense. I think that I could try to acquire some glass cabinet on some stupid estate sale, or a cheap used fishtank, fill it with argon from my tig welder, and make some funny arcs inside.

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Reply to
Ignoramus27736

Yes, this is a franceformer. I have about 4 franceformers, and 9 other brands, all very similar in dimensions and appearance. Total 13.

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Reply to
Ignoramus27736

As it turns out, Franceformer is a company, a part of Scott Fetzer Co, which is itself a part of Berkshire Hathaway. I own a tiny bit of that company's shares, in fact.

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Reply to
Ignoramus27736

This is somewhat related, since it involves a sign transformer. flames conduct electricity:

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On the left is a propane tank connected to one 7500v leg of a 15kV transformer, and the right lead attached to the other 7500V leg.

Reply to
Cydrome Leader

go here and learn a little about tesla coils - I'm trying hard to point you to a venue where you can make some $$ off those things - but I won't post more on the subject now - it's up to you - fragment of mail from listserv below:

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Reply to
william_b_noble

Yes, they can theoretically be connected in series if you float the cores, but then you run into the problem that the cases are connected to the cores, the on/off switch is screwed into the case, the primary cable runs through the case, or (as William Noble pointed out), the primary/core insulation isn't rated for 4.5kV.

In other words, it's not practical given the structure and the voltages involved. Put one volt into the primary and it would work, but without significant reworking of the transformer itself (depotting/immersing in oil/reworking leads/insulating the primary), it isn't practical at 120VAC.

Jon

Reply to
Jon Danniken
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Reply to
MK1

Huh?? Did I see the same pix?

Reply to
Brian Lawson

All true -- but if you have 13 of them and they were cheap, how could you resist trying it with a couple? HV stuff is designed with pretty generous margins because insulation, etc degrades over time in the presence of HV.

Reply to
Don Foreman

My units are quite old, in fact. After carefully thinking about these issues, I realize that they cannot be put in sequence, unless I find some cheap isolation transformers. I get nice sparks with 9 kV, I can live with that for now.

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Reply to
Ignoramus29878

Back in the stone age when I was doing science demos at a local science museum, we aquired a Tesla coil that used some monster old radio tubes rather than the spark gap system to generate the high frequency. As you said above, it was nearly silent while making foot long sparks. The sparks were more brush like (softer looking) than the standard spark gap unit we had.

The really cool thing about this unit was...no leaked low frequency in the sparks. You could stick your hand right in and not have the usual shock you often get from Tesla's. It did leave tiny pin prick RF burns on the surface of your skin (not deep enough to "feel").

As a demonstration piece, however, people in the audience really missed the snapping and crackling.

Koz (who once took a solid direct hit of a 3-1/2 foot tesla spark while well grounded and screamed "aww...FU**!" to an audience of kids as he jerked a couple of feet. )

Reply to
Koz

Try quickly pulling a piece of typing paper through the arc. Do it fast enough that the paper doesn't light and you will see perforated holes showing that the arc is not continuous as it appears....after all, it is AC.

Koz (who did this as part of the science demos also....Kids have no clue that AC from your wall socket is not the same as DC from a battery)

Reply to
Koz

I suspect they heard that word before..... Look at the bright side. At least you didn't expose them to something that would mar them for life. Like seeing you electrocuted (or pee your pants).

Reply to
Chuck Sherwood

And I bet none of them burst into flames upon hearing it,either.

Or a half-second glimpse of a nipple during the superbowl half-time show or something. Now that, would be life-changing. Or something like that.

Seriously, a 3.5' spark...have you calculated the voltage for that? That could have been a game-over type event, no?

Reply to
Dave Hinz

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