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Post by lamazoid on Jun 22, 2017 10:40:37 GMT -8
1.5 mm is Definitely an Excessive LARGE GAP. A 0.06 mm Piece of material, Just placed on the Two Outer rectangles will create a more suitable 0.06 mm gap on the round center pole. Simple and No Grinding.yes but will it have desired inductance?in my discourse, i am guided by Manfred's cosmic revelation about the true essence of inductors and transformers: ludens.cl/Electron/Magnet.htmli've made a simple Excel file to calculate required number of turns (to avoid saturation) and also required inductance to get certain amount of power. the disadvantage of typical power ferrite core is relatively high AL vs core cross-section. EPCOS makes gapped cores, but they also are not optimal for our design, since we need to store relatively large energy per cycle, with relatively low input voltage. by the way, it's also a reason why typical power electronics books avoid describing flyback topology as low-to-high voltage step-up.
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Post by Gary Lecomte on Jun 23, 2017 6:55:39 GMT -8
I have made Many Low to High Voltage Step Up Transformers. This is a Small one I presently manufacture for a US company. Approximately a 1 Inch cube, 12 Volts in, 10KV out and runs at 6Khz. Obviously this one is Not for High Power, Just High Voltage. When Finished off, it gets Potted in a special Wax to prevent Arcing. But I have also made some High Voltage and High Current ones using those Big E-Cores. One was 12 Volts and 30 Amps in, 4 KV out.
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Post by lamazoid on Jun 23, 2017 10:51:21 GMT -8
View AttachmentBut I have also made some High Voltage and High Current ones using those Big E-Cores. One was 12 Volts and 30 Amps in, 4 KV out. Propably you have push-pull topology in that?
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Post by Gary Lecomte on Jun 23, 2017 15:45:29 GMT -8
Yes, The Best way to go for High Current and High Voltage. But I have also done some Large Flybacks. The Small One I pictured above is a Flyback. One circuit I designed.
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Post by lamazoid on Jun 27, 2017 12:27:09 GMT -8
second prototype:
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Post by lamazoid on Jun 27, 2017 12:41:27 GMT -8
it took a lot of f**k to get UC3843 work properly ( to match calculated params of charge and discharge cycles of inductance), it has even required adding slope compensation to the current feedback loop. finally, it works in static tests (with an resistive load) , but i did not tried to weld yet. i have a constantly growing wish to take a hammer and destroy this crap to hell it seems, for this purpose best choice will be simple 555 ic driver (just like Gary's fencer design) with MANUALLY adjusted frequency and duty cycle. anyway, hammer will wait (at least) for weld testing.... then we'll see, if 500W is enough or not.
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Post by Gary Lecomte on Jun 27, 2017 15:22:54 GMT -8
I Doubt my Fencer circuit (or Similar) would be of any Help for your needs.
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Post by lamazoid on Jun 28, 2017 1:47:57 GMT -8
I Doubt my Fencer circuit (or Similar) would be of any Help for your needs. why? it's simply on an off with required timing. weak output of 555 is not a problem, since i use 4A driver IC made by TI. currently i got 24us ON time and 33us period, but it should be 27/33 , and i can't get it with 3843, cause with too low slope it falls into parasitic oscillation. (and too high slope results in less ON time)
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Post by Gary Lecomte on Jun 28, 2017 5:13:54 GMT -8
Do you have a Schematic as to: "How your applying this High Voltage to the 12 Volt Battery"
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Post by lamazoid on Jun 28, 2017 8:31:39 GMT -8
Do you have a Schematic as to: "How your applying this High Voltage to the 12 Volt Battery" ou have a Schematic as to: "How your applying this High Voltage to the 12 Volt Battery" I meant simple, no feedback, fixed-time control circuit. just as you have in fencer, but of course without HV stage
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Post by lamazoid on Jun 29, 2017 9:48:00 GMT -8
a MUCH better weld with 2mm rod, 2mm steel stripe: at this time, boost converter power is about 350W. and it's almost enough for 2mm rod. what's curious, the welding works only on direct polarity ("+" on the rod). but the correct polarity with DC welding should be reverse: "+" on the workpiece, "-" on the rod. when i try to reverse polarity, it blows the fuse at the booster input (50A). and even when i bypass the fuse, it simply does not work. e.g. _literally_ DOES NOT. the arc simply can't start. curious....
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dave
Junior Member
Posts: 56
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Post by dave on Jun 29, 2017 14:57:58 GMT -8
a MUCH better weld with 2mm rod, 2mm steel stripe: at this time, boost converter power is about 350W. and it's almost enough for 2mm rod. what's curious, the welding works only on direct polarity ("+" on the rod). but the correct polarity with DC welding should be reverse: "+" on the workpiece, "-" on the rod. when i try to reverse polarity, it blows the fuse at the booster input (50A). and even when i bypass the fuse, it simply does not work. e.g. _literally_ DOES NOT. the arc simply can't start. curious.... Hi Lamazoid , straight polarity with dc is electrode negative . Reverse polarity is electrode positive . Around 70 % of the heat is generated at the positive pole .I don't know much about your circuit as I'm not an engineer like some of you guys but I think this may have something to do with direction of current flow in the components . I have over 40 years experience as a welder and would really like to see you develop this idea , good luck mate . Cheers , Dave.
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Post by tolik212 on Jun 30, 2017 11:28:33 GMT -8
Something affects the control circuitry - one of feedback loops. Probably current FB. This accurate measurement network quite sensitive to parasitic products from all kind of transients.
I was always sure, that current should to follow from + to -, otherwise , the circuit just isn't working at all... Especially solid state semiconductors based
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Post by lamazoid on Aug 8, 2017 1:18:40 GMT -8
finally got PCBs from factory. this is AL based material, for maximum heat transfer.
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Post by lamazoid on Oct 24, 2017 12:19:45 GMT -8
recently, i went in situation, where this welder could help. while off-road driving, i got exhaust pipe break apart )) that was a loud SOUND, hah )) 2mm rod could help. or either a MIG setup with pulverized (no-gas) wire... so this project is not forgotten, despite i still have no time to get my hands on it..
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