[time-nuts] 4 KV Power Supply Recommendations

[john.foege at gmail.com]

You can get brand new MOTs (microwave oven transformer) from eBay for quite cheap, or simply scavenge them from old microwaves.

As has been stated, they have magnetic shunts between the windings on either side. These shunts make the transofmer non-ideal and horribly mess with the tranaformers regulation as far as I can remember.

These shunts can be pounded out; being careful of course not to damage the windings which are made generally from aluminum wire and then enameled.

With an American type MOT, you'll get about 2.2kV-2.4kV on the seconday side. As also was stated in previous emails, the insulation the secondary winding is too thin and cheap, which is why one side is tied to the transformer core. I've heard of people lifting this connection, but it's certainly not a good idea.

One thing to do is mount the MOT on a piece of wood that insulates it from the case you are using.

Another very handy trick to make the MOT much less lethal for use, would be to wire a standard incandescent bulb in series with the primary. this limits the seconday side current quite nicely.

John Foege
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-----Original Message-----
From: Bob Camp <lists at cq.nu>
Date: Sun, 17 Jan 2010 20:33:16 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Subject: Re: [time-nuts] 4 KV Power Supply Recommendations

Hi

You also could leave the windings as is and feed the secondary voltage into a voltage multiplier. Still not very safe to wire up. 

If you did wire it up, the available current would be pretty massive. I certainly would not attach it to an ion pump I cared about.

Bob


On Jan 17, 2010, at 6:53 PM, Stanley Reynolds wrote:

> 
> 
> 
> 
> ----- Original Message ----
> From: Chris Stake <stake at btinternet.com>
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Sent: Sun, January 17, 2010 5:05:01 PM
> Subject: Re: [time-nuts] 4 KV Power Supply Recommendations
> 
> What is the operating voltage of the magnetron in a domestic microwave oven?
> Although VERY HAZARDOUS, it might be possible to adapt the PSU from an old
> one?
> Chris Stake
> 
> Yes, if you remove the transformer shunts and the filament windings and add more primary windings in the space you would get about 2700v with a full wave bridge. You also need to lift one side of the secondary that is grounded to the frame. Yes very dangerous and yes I'm luck to be able to tell.
> 
> Stanley
> 
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