I am trying to figure out 11 frequencies (selectable by 11 position rotary switch) for square wave AC welding inverter. I have a spreadsheet where I put which capacitors I use on every position, and get the frequency for this position. After messing around a bit making sure that I stay within the number of caps that I have right now, I came up with this list of frequencies, in Hertz:
556 417 333 278 249 192 156 139 111 94 74 46Is that a sensible choice?
i
I seem to recall pulse frequencies as low as 20 Hz being useful, and do not recall any use for the higher end of your range, but my recollection is probably a bit out of date. What frequency ranges do commercial inverters use?
You just made me go and check the manual on Miller Aerowave, the most expensive $10,000 tig welder. Their frequency range is from 40 to 400 Hertz. Mine is about same, with the extra 550 Hz frequency value that might be useless.
After (and if) my project completes, I will have a welder comparable to Aerowave. Fully programmable, 8-92% cleaning/penetration control, etc. The only difference that I could see (with my limited knowledge and experience etc), is that Aerowave can have different EN and EP currents, and I cannot, plus Aerowave can do 300 amps at 60% duty cycle and I am limited to 200 amps, 100% duty cycle.
i
Why mess with switching the capacitors? Since precise frequency is not important in TIG why not use a VCO ( voltage controlled oscillator ) and a potentiometer? It would save you lot of wiring. If you want to get fancy you can hook up a frequency counter panel meter to display the frequency.
Regards,
Boris Mohar
Got Knock? - see: Viatrack Printed Circuit Designs (among other things)
void _-void-_ in the obvious place
You're supersititous.
robert
I am open minded here. If you point me in some right direction, for something easy, that allows control of percentage of positive vs. negative in the cycle and not just frequency, I will be happy. If not, I can do with the switch.
The reason why I chose XR2206, is that I can control both frequency as well as percentage of + and - cycles.
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