[time-nuts] No more 60Hz, How do I discipline 120VAC 60Hz from a UPS

[Will Matney]

John,

A lot of it depends on the design of the transformer, or how close to
saturation its core is ran, and the way the laminations are stacked. The
inverters that were self-oscillating, and used "tickler" bias windings,
depended on saturation to work correctly, and the transformer determined
the oscillation frequency. If you're using a driver/oscillator, you don't
need a saturating transformer, but since square waves might be involved,
there is a different formula you use to design them. Also, you can make the
stack, 1/2 butt stacked, and 1/2 interleaved.

What I found in using a transformer, ran at a lower flux density, is the
best to use in this, say around 10 kilogauss. I think some of the so-called
filament transformers were designed with just enough iron in them to get
by, and ran close to saturation to begin with. I de-rated the power on the
inverter I built, and it was running a modified square wave, and I got by.
Also, I've read that a triangle wave is good for this, or better than a
sqaure wave. Now, I wouldn't have used the transformer I did with a pure
square wave, as it most likely would need to be modified for use like the
author found out.

Take a look at Wikibooks for Transformer Design, and it tells a lot of info
on this.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 6/25/2011 at 5:40 PM John Miles wrote:

>The C. S. Stong 'Amateur Scientist' anthology included a 110V 60 Hz
>telescope-tracking drive generator project that used a reversed filament
>transformer.  It was a bleeding-edge design for the time, using a CK722
Wien
>bridge oscillator (complete with HP-style pilot lamp AGC) and a couple of
>early germanium power transistors.  The author found that he had to rewind
>the transformer to cut down on saturation loss, but he was otherwise able
to
>get it to work OK with the crude solid state technology available at the
>time.
>
>The author didn't say as much, but I wonder if transformers sold as
>'filament' transformers were designed to saturate intentionally, to limit
>the inrush current they would otherwise apply to cold heaters.  I would
>expect modern transformers to work better, just because their
manufacturers
>are more concerned with minimizing losses than they were back in the day.
>
>-- john, KE5FX
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-
>> bounces at febo.com] On Behalf Of Neville Michie
>> Sent: Saturday, June 25, 2011 5:03 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] No more 60Hz, How do I discipline 120VAC 60Hz
>> from a UPS
>> 
>> 
>> An interesting question about making a 50/60 hertz source,
>> Does a 120 to 12 volt transformer have enough inductance to use as a
>> 12 to 120 volt transformer?
>> Remember, the inductance is proportional to the square of the no of
>> turns, where as voltage is proportional.
>> cheers,
>> Neville Michie
>> 
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