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Learned about an HF welder today

I learned something interesting today, that is probably common knowledge to most welders. I have a friend that welds, mostly on marine equipment. He came to me wanting a switch installed on his tig torch to help him tig some anodized aluminum. He has an HF251-D1 high frequncy unit and a Trailblazer

302. I found a schematic for the High frequency unit, but was a bit perplexed as I couldn't locate any semi conductors that I thought would be used to generate a high frequency. Well, later in this process I found out that the thing operates like a tesla coil with a spark gap to create the high frequency.

Now, in order to figure this thing out I wanted to see it operate, So the welder went on to show me and it would not work. He could not get any high frequency arc. He said it worked fine last night, Ok, "so what did you change"? He had added about 70 feet of cable, OK, so let's take that cable out. So now the HF works fine, It turns out the cable was wound up making an inductor that would not allow the HF to operate properly. Once the cable was straighted out it worked fine. So.. the HF unit uses a spark gap to create HF and you can't coil the wire and use an HF unit. I thought it was interesting. Mikek

Reply to
amdx
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I learned something interesting today, that is probably common knowledge to most welders. I have a friend that welds, mostly on marine equipment. He came to me wanting a switch installed on his tig torch to help him tig some anodized aluminum. He has an HF251-D1 high frequncy unit and a Trailblazer

302. I found a schematic for the High frequency unit, but was a bit perplexed as I couldn't locate any semi conductors that I thought would be used to generate a high frequency. Well, later in this process I found out that the thing operates like a tesla coil with a spark gap to create the high frequency.

Now, in order to figure this thing out I wanted to see it operate, So the welder went on to show me and it would not work. He could not get any high frequency arc. He said it worked fine last night, Ok, "so what did you change"? He had added about 70 feet of cable, OK, so let's take that cable out. So now the HF works fine, It turns out the cable was wound up making an inductor that would not allow the HF to operate properly. Once the cable was straighted out it worked fine. So.. the HF unit uses a spark gap to create HF and you can't coil the wire and use an HF unit. I thought it was interesting. Mikek

Reply to
amdx

Cable on the input or output? If on the input you could probably slap a suitable capacitor across it (at the welder) and get it to work.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

And the FCC is going nuts wit all of the gruesome RFI complaints. Spark gap transmitters are almost 100 percent illegal now. "Almost"? if that was the only to transmit an SOS in a life-and death situation, then it is "just" barely acceptable (but do not do that again).

Reply to
Robert Baer

Bullshit!

Hobbyists operate tesla coils and it is legal as long as you don't get too many neighbours complaining. They also operate in museums and at shows. Also some medical electrosurgery units that are still in use today use a spark gap.

Reply to
Shaun

Shaun expounded in news:OlF7p.44630$y snipped-for-privacy@newsfe10.iad:

I still have my Model-T 6V Ford ignition coil, that I bought on ebay (I was hoping then to interest my son in electronics). I haven't operated it in a little while ;-)

When I was young, I had made an HF coil using a paper towel cardboard roll form, and an outer coil of a dozen turns or so. There was a HV cap involved to cause it to resonate.

I'm not sure what the output freq was, but it was fun drawing sparks to your hands. Being HF, it would only tickle slightly.

I'd love to know what the lowest minimum frequency for human tolerance of HF HV arcs is.

I once knew a guy that claimed that he'd test TV HV power supplies by arcing the transformer +HV lead to his fingers (approx 15.7 kHz). I've never had the guts to try it.

Warren

Reply to
Warren

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