[Fritz] built this 600 joule capacitive discharge spot welder in a case scavenged from a Lincoln plasma cutter. All of the circuitry was designed by [Fritz] and the schematics are available on his website. He has a few other welding related project also documented on his site that are worth checking out. While this isn’t the first homemade spot welder we have seen, it is definitely the first one with a case mod. If you are not up to the challenge of building one quite as complex as [Fritz]’s example, a microwave can be used as the donor appliance in simpler designs.
When [linux-works] found himself needing a switch that could convert coax to opto, he made one. The main chip is a cd4052 cmos analog switch, which he says is really cheap. The rest is pretty self explanatory. This setup can switch between 4 different inputs as well as do the coax to opto conversion.
[Ben Nelson] didn’t even know how to ride a motorcycle when he started on this electric conversion of a 1981 Kawasaki KZ440. The engine wasn’t a loss since the bike was nonrunning when he purchased it for $100. The permanent magnet Etek motor was $500 and each of the four yellow top batteries were $160 (only three pictured). He says that the majority of the conversion work only took two weekends. The resulting, still street legal, ride averages 20 miles per charge with a 45mph top speed.
