50Hz mains to MHz range? Can it be done?

[neazoi]

Hello, this is a bit weird question
Is there any way to convert 50Hz mains (stepped down to 30V or so) to a high frequency signal, say 1-10MHz?
Any PASSIVE technique you can think of. some kind of mixer or harmonics multiplier.
I am not thinking of an oscillator, I said passive.
Thank you

 

[etmabreu]

Sure. 1Mhz is the 20.000th harmonic of 50Hz. Good luck!

 

[neazoi]

So only harmonics generators could theoretically achieve this? Any other way?
All crazy ideas are welcome

 

[biff44]

use the 50 hz to drive a motor. Have the motor turn the shaft of an RF generator like tesla would have built.

 

[BradtheRad]

This method is interesting even if it is impractical.

Frequency doublers, driven directly by the AC source. Three in a row makes an octupler.

The output amplitude is greatly attenuated. It is not a sinewave.

 

[neazoi]

use the 50 hz to drive a motor. Have the motor turn the shaft of an RF generator like tesla would have built.

A stepper motor should give spikes of higher frequency with relatively slow turns I think

- - - Updated - - -

This method is interesting even if it is impractical.

Frequency doublers, driven directly by the AC source. Three in a row makes an octupler.

The output amplitude is greatly attenuated. It is not a sinewave.

Very interesting circuit! Why not using this in combination with a voltage doubler?

 

[etmabreu]

use the 50 hz to drive a motor. Have the motor turn the shaft of an RF generator like tesla would have built.

1 MHz -> 60.000.000 rpm

Good luck with that generator and all the gears...

 

[godfreyl]

1 MHz -> 60.000.000 rpm

Good luck with that generator and all the gears...

Actually, the idea's not as dumb as it looks at first glance. Alternator based radio transmitters were actually used about a century ago, before tubes took over. Back then they got up to about 100KHz or so. See for example this and this. The trick is basically to use an alternator with several hundred poles.

 

[betwixt]

Google for "Grimeton", there is still one Alexanderson Alternator in working order and it was run a few years ago to test it.

I doubt that would be a viable solution for 1MHz though. If I had to tackle the problem (although I can't think why anyone would), I would start with something to generate sharp 50Hz pulses, possibly an SCR or Triac with peak cycle triggering, then feed it to a high-Q tuned circuit to extract the harmonic of the pulse edge rather than the mains itself. Please don't ask about efficiency - there wouldn't be much!

Brian.