[R-390] Rube Goldberg 400 cycle ac

[Bob Camp]

Hi

I don't know how many have taken a look at the output of a UPS on a 
scope. If you ever get a chance it can be a significant surprise. These 
days the waveform rarely is anything close to a sine wave. I'm not sure 
that you can run everything on those weird waveforms but they seem to 
work for most stuff.

A two step sine wave approximation is a whole lot closer to a sine wave 
than the stuff that a UPS puts out. A multi winding filament 
transformer and four cheap mosfets should get you quite a bit of power. 
If you find a source for several identical transformers then three 
phase would work the same way. In either case a pretty small chunk of 
code on a PIC processor would give you all the drive waveforms you 
would ever need. Makes all the turn off this one before you turn on 
that one stuff fairly easy.

	Enjoy!

		Bob Camp
		KB8TQ




On Aug 17, 2004, at 6:36 PM, Bill Hawkins wrote:

> The audio amplifier works just fine. I found a 200 watt SS
> amp for a building system that ran off 28 VDC or 120 VAC.
>
> Years ago I had a WWII gyrocompass with a 3 phase 400 cycle
> motor. Found a small 28 VDC to 400 cycle, 115 VAC that was
> single phase. Hooked it across two of the three phase wires
> and connected a 2 mfd cap between the third and either of the
> two power leads and spun up that gyro.
>
> The thrill faded, as thrills do, and I lost track of the stuff.
>
> Sometimes you can find cheap old frequency synthesizers that
> don't reach high enough to be interesting to most people.
>
> If you're really a fan of Rube, you can build an inverted RC
> phase delay circuit (180 + 60) after a 400 Hz oscillator and
> feed 2 audio amps to get something close to true 3 phase power.
>
> Regards,
> Bill Hawkins
>
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