[time-nuts] 4 KV Power Supply Recommendations

[Bruce Griffiths]

For a Cockroft_Walton multiplier with m stages with all capacitors equal 
except for the first which has twice the vale of the others the output 
resistance is

~ (2/3)*m*m/f*C

Where the first capacitor = 2C and all the other capacitors =C

f is the line frequency

The accuracy improves as m increases.

Bruce

J. L. Trantham wrote:
> The more I read about this, the more I think I will just let it 'pump'.
>
> This evening, the voltage on pin 4 is -1.039 VDC and the HV is up to 2151
> VDC.
>
> I was wondering how to limit the current capacity of an old HV transformer,
> say 750 VAC, power supply and I suspect it is all in the size of the
> capacitor.  I will have to do some calculations about that.  I was thinking
> of using enough diode/capacitor units to multiply up to around 5 KV with a
> variac to drive it and have taps from the diodes along the way for lower
> voltages as well.  If I can just find my old transformers.  However, the way
> work is now, I suspect the tube will be pumped down before I get around to
> this.
>
> I'll keep my eyes open for HV power supplies on eBay as well.
>
> Thanks for all the info and I'll let you know what progress occurs.
>
> Joe
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Stanley Reynolds
> Sent: Sunday, January 17, 2010 8:38 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 4 KV Power Supply Recommendations
>
>
> Yes even with the mods odds are good the secondary is not well isolated from
> the frame and even with the extra secondary windings the primary loading is
> high per turn and load regulation is poor. Over all microwave transformers
> are not very good, if you goggle them plenty of info and speculation about
> them. If
> you have a matched pair you can turn then into a center grounded
> configuration. There are ways to limit current and voltage like the
> incandescent bulbs in the primary, or the autotransformer already
> mentioned, but mistakes could be costly. HV resistors or strings of
> resistors could also be used in the secondary to limit current.
>
> / rambling on
> Not sure working on very old cesium standards is very safe much less using
> factory made PS at KVs to revive old tubes but some people jump out of
> perfectly good air planes in the name of fun. HV power supplies are scary
> and yes I have ended up on the other side of the room with a odd metallic
> taste in my mouth, not sure why I lived so long ? $200 to ebay sounds better
> than the cost to replace a time-nut, at least this one:-). If you do live to
> see your homemade power supply working maybe your luck will hold with the
> tube repair, did for me but I only got a few months of lock light and I'm
> back to square one. / rambling off
>
> Stanley
>
>
>
> ----- Original Message ----
> From: Bob Camp<lists at cq.nu>
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Sent: Sun, January 17, 2010 7:33:16 PM
> 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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>>      
>
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