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Portable home made welder alternator.

Balancing it all out

Why build when you can buy?
Choosing the right engine
Choosing an alternator based on your engine
Keeping it ........ Exciting
The sum of all the parts. Hooking it all up.
Balancing it all out
Putting the welder to use
Injury and or death
Credit where credit is due.

This is where we make it operate properly, meaning the engine dosn't overload when welding and your arc is maximum strength.  By improving efficiencies or building in inefficiencies we match the alternator to the engine.  One way of boosting alternator output is to place a capacitor bank on across the brushes.  A way of reducing output is to half wave rectify the brush input with a pair of diodes.  Another simple way of reducing output is to place  variable resistors or 12-24 volt 50-100 watt lightbulbs in line with the brushes and the field input.  
It is important that the alternator isn't pulling more mechanical energy than the engine can offer otherwise the engine bogs and the welder is useless.





This photo shows both built in efficiencies and inefficiencies.  The pair of diodes are used to rectify a small engines alternator, bypassing the engines built in regulator, and allowing higher output voltages.  A full wave rectifier or bridge rectifier (4 diodes) will further increase the output This is useful when adapting a 24v alternator where a field voltage of 12v is inadequate.  The Capacitor further increases the alternators output by filtering the ripples to the field.   

  This diagram shows a slightly different way of exciting the field.  A battery can be used to excite the field for a few hours.  The lamp is a 12v  headlamp (if needed) wired in series to reduce the fields input.  The higher the wattage (usually stamped on the bulb) the more  current is allowed to pass to the field, more ouptut is being developed, and more load is applied to the engine. The lower the wattage the less current is allowed to pass, less alternator output is developed, and the less an engine is loaded.   
  These principals are important to matching the alternators output to the engines highest power output at around 3600 rpm for most small engines.  Too much excitement and the engine will be loaded excessively.  Too little and the welder will not develop  its full output at all RPM's. 
The output of the welding machine is regulated only by rpm's once it is all matched up.  The faster the engine turns the more amps it is capable of delivering,

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