[time-nuts] Transformer design.

Will Matney xformer at citynet.net
Mon Jun 27 19:30:43 UTC 2011


I have several units made by ESI that I use for this, and one is the big
3-piece rack unit that contains the bridge, and the two suppies with the
detectors, one a mirror galvenometer. I also have one of their 4-1/2 digit
LCR meters for the bench, and three smaller units, two digital, and one
analog 250BE. It seems like you can sneeze sometimes, and change the
reading, just by the leads placement, when trying to do some exact
measurements. The test leads have a lot to do with it, in and how they're
made. I noticed some of the new Asian made Kelvin leads using two plain
wires to each clip, and I can see headaches trying to use them. All mine
use shielded, twisted-wire leads, and you still have to watch on them. I
use a panel mounted fixture for all small work, where there is no lead
length to worry about.



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On 6/27/2011 at 12:08 PM Brooke Clarke wrote:

>Hi Will:
>I got interested in RF coils and spent a couple of years winding coils, 
>and measuring them on a Boonton Q meter.  That led to Tesla and I got a 
>number of his publications.  It turns out that a Tesla coil is not 
>magical, it's just an RF transformer where the primary and secondary are 
>resonated.  I took him some time to find a mechanical structure (pipe 
>mast insulated by wine bottles with a capacitive top hat).  The high 
>school "Tesla Coils" really are just RF transformers because they omit 
>the resonance on the secondary.  Tesla did not understand Q and thought 
>it was something magic.
>Measuring impedance is very different than measuring things with 
>connectors, both in terms of backing out the connection parasitics and 
>in terms of using a measurement method that minimizes errors (for 
>example network analyzers only work when the impedance is within a 
>couple orders of magnitude of 50 Ohms).
>Have Fun,
>Brooke Clarke
>Will Matney wrote:
>> ...
>> I encourage any on here to add to it, especially in the design of RF and
>> audio impedance transformers. I wanted to do more, but never found the
>> to set down and do it, plus I never really designed that many of them,
>> power transformers. What I wrote was the basics, but didn't get into any
>> formulae, etc, which I would have liked to have seen included. Any help
>> would be appreciated, not just by me, but our entire electrical and
>> electronics community as a whole, especially any students who read it. I
>> even found a link on Google, from a Russian university, who had their
>> students read it at one time.
>> Thanks,
>> Will
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