http://theepicenter.com/tow02077.html

Looks like a neat project if you have a motor and alternator around, and you like to tinker.

 

Haven't built one, but worked on some welders (can't remember the brand name) that was made from a GM 24volt alternator (with regulator removed), belt driven from a small engine. Instead of the regulator it had a rheostat and some other circuitry to let you adjust the current. The alternator was one of the big jobs, like a 130 amp or so, was set up to run at a pretty high RPM, and the exciter voltage was fairly high. It actually put out around 150 amps at weld voltage and the open circuit voltage was around 60 volts. It worked pretty decent, but even with a double pulley v-belt system, it was prone to smoking the belts when loaded heavily and the brackets were prone to breaking from the vibration. I'd say a newer style pulley system with a ribbed belt and a solid plate mount like the one in the link you posted would solve that. I'd like to make one that ran at a lower RPM (to make it 60HZ), and use a small welder transformer (I have a couple laying around). I'd run the transformer in reverse (primary and secondary reversed) to step up the voltage to 115. Not REAL useful, but might help in a pinch. Given that I've got engines and transformers, if I could find a BIG used alternator, it'd be cheap. The price you'd have to give for a new alternator of that size would probably exceed the price of a comparable generator, though. It'd be fun anyway. Heck, I just came from the garage, where I'm building my own MIG wire feeder. When finished, it'll be better than what most weld shops are running and I'll have less than $100 in it. I love DIY projects!

 

Interesting.

My boss has a Pontiac of some sort on his acreage, that is supposed to be donated for salvage; I think I'll check out that alterneator first, then keep my eyes open for a motor.

 

I made such a thing a few summers ago to be incorporated into a project that I never started due to lack of time that year. Then I buried the powerplant in the garage somewhere for later use so my apologies for not offering pictures.

Mine's comprised of a 60A-ish alternator, an old self-oiling air conditioning compressor, and an electric start horizontal 8HP honda engine. Using GM FWD serpentine pulleys and a GM FWD belt tensioner, I interconnected the three pulleys so the honda engine drives both the AC compressor and the alternator. 8HP is probably not enough to get "full power" out of the alternater and the AC compressor but for the purpose I was making this it was more than enough.

I rewired the honda engine so the internal alternator is no longer part of the circuit and simply along for the ride, using the GM alternator to recharge the motorcycle battery as well as power the ignition on the honda engine.

The way things are arranged, looking at the pulleys, the engine is on the right, and the alternator is on the top left, and the AC compressor is underneath the alternator. The serpentine belt goes around all three pulleys, and the belt is pulled between the alternator and the compressor towards the engine, to go around the tensioner. This ensures that there is maximum contact between the belt and the alt/comp pulleys to prevent slippage.

Underneath the engine and accessories, is a large "pancake" air compressor tank of maybe 4 gallon in size (just a guess) I picked out of the trash and the compressor fills that nicely. I installed an electric air compressor switch assembly that powered the AC compressor's clutch when pressure drops below something like 85 psi and disengages the clutch when pressure reaches 125 psi or something like that. That part is broken so I manually actuated the clutch by connecting and disconnecting a spade connector while watching a pressure gauge. This was just to test if my plumbing "held air" so that was fine. Just have to replace the pressure switch thing and it''s good to go.

 

I made a light plant once for night fishing in the Gulf. Took a 3 1/2 HP horizontal shaft engine and drove a 60 amp chrysler alternator with it. At first I used a stock chrysler regulator but had trouble getting 12 volts to carry the load over any distance without having to use welding cables. (Who wants a roaring engine close to the fishing spot).
Finally I settled on just feeding the field of the alternator with a solid 12V from a battery. This let the alternator put out around 100 volts which very nicely ran 4- 24 volt aircraft landing lights wired in series. I swear I could almost see the steam comming off the top of the water from the heat of the lights.