Someone Here Might Know?


Newly Enlightened
Feb 12, 2005
I know this is a ligth source forum but it seems as though everyone on here is really knowledgeable with all sorts of electrical issues.

I am looking to convert normal 115V 65hz power(from a normal house plug)to 115V 400hz for testing aircarft type motors. It doesn't have top be very highly developped and really would be great to ba as simple as possible. I only need a single phase/115V/400hz/ 3-5 amp max power source. I do the final testing with a regulated power source that costs around 5,000.00 dollars and calibrated yearly. I am just looking to provide 5-6 work stations to do preliminary and functional testing for trouble shooting.

Any help with this would be greatly appreciated.


Eric Wallace

Doug Owen

Flashlight Enthusiast
Jan 30, 2003
Best way out is probably a motor generator.

Years ago I had a very similar problem, setting the presets on some aircraft generator PCBs so I needed variable voltage 400 Hz power. As it happened I was also working on a lawnmower engine driving a Dodge truck alternator. It was easy to set the Briggs and Straton speed and pulleys to get 400 Hz and controling the field gave me the variable voltage part. All I did was tap off a single phase of the three phase going to the rectifier bank in the alternator loading the three phases with 3 light bulbs as a delta.

You could no doubt screw a fractional HP electric motor to a board, mount the alternator and connect them with a fan belt and pulleys. A bit of math with the pulleys should get you close enough for jazz.

Be sure to cover or otherwise guard the exposed belt.

Is that clear enough to understand?

There are of course factory made units that do this, often used in high power radio transmitters. There's an Italian outfit that sells in the EU I bought such a unit from some years ago, but we're talking serious bucks.

Doug Owen