throbscottle
Well-Known Member
I have been re-visiting the idea of building a capacitive discharge welder such as used for battery tabs, for which 1F car audio "stiffening" capacitors are popular, but seem to have got rather more expensive since I last looked. One of these should store about 72 joules at 12v. I've seen a project for one that uses 220,000uF at just over 20v, so that stores 44 joules and looks to be the minimum needed. So aiming for the higher amount of energy within that voltage range, no matter what value/voltage combination I use I can't build a suitable bank of capacitors for less than £25-£30
I did read somewhere that the commercial ones use a smaller, higher voltage capacitor and a pulse transformer to drop the voltage, and found that I can build a smaller, higher voltage (eg 100v, 200v) bank that will store the same amount of energy, much cheaper. So I would just need a transformer to drop the voltage to a suitable level.
Any thoughts on how big a core I would need? Bearing in mind it's only to weld thin metal like battery tabs and emi shields.
I did read somewhere that the commercial ones use a smaller, higher voltage capacitor and a pulse transformer to drop the voltage, and found that I can build a smaller, higher voltage (eg 100v, 200v) bank that will store the same amount of energy, much cheaper. So I would just need a transformer to drop the voltage to a suitable level.
Any thoughts on how big a core I would need? Bearing in mind it's only to weld thin metal like battery tabs and emi shields.