On Oct 30, 7:13 pm, jb-electronics <[email protected]> wrote: > Remains the question about the spot welder. MOT or caps? I have to say, > I slightly tend towards the MOT solution because it appears safer. What > do you say?
MOT is probably safer and far less complex. You can use the cabling from a tough set of battery charger leads or, as I do, use the cable used by welding machines (very flexible & high current). Use a solid-state relay trigger to switch the MOT with a monostable set to about 100mS. If you want to be cute, add a "lock-out" period after firing of about 500mS to prevent continual firing & abuse. Use brass, not tungsten, electrodes. Cut both secondaries off the MOT with a hacksaw - that is the HV one (fine wire with one end actually connected to the MOT EI cores) and the magnetron filament winding (a few turns of very heavy wire in the middle). Add new windings - about 5 should do, of your very heavy secondary wire - you should aim for about 1.5V at a couple of 100 Amps. Using the monostable means that you can overdrive the cable as you are only powering it for a very short time - secondary should be using something like 4 AWG wire. Make sure you earth the EI core and fuse everything - primary should have slow-blow fuses. Make sure your solid-state relay is rated for inductive loads and has a snubber network... use a mains filer to prevent the cr*p getting back into the house power. If you can afford it, use a zero-crossing solid-state relay. Its simple to do this with discrete components - avoid uPs - they may well object to the huge current pulses flying around and are a completely unnecessary complication. eBay 380381237513 looks like a suitable SSR at a fair price. HTH Nick -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
