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From: "Smile, it can only get WORSE"
Subject: Re: low loss transformer availability?
Date: Sat, 04 Jan 2003 21:51:03 -0500
Organization: Posted via Supernews, http://www.supernews.com
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RL and others....
OK, I read all the comments and thank you all.
Here's a reply to all the comments posted previously, forgive me for
not posting separate replies.
I need a transformer that has a high impedance input-so that it
doesn't draw much current from the driver source when there is only a
small load current being extracted from the secondary. I was hoping to
operate at 3 mhz because it's easier to make a high impedance primary
when the frequency is higher and 3 mhz is fairly easy to work with.
In reality, I might be able to go down to 100 kilohertz or as high as
I need 12 V AC RMS in..... and (about) 120 V AC RMS out.
Even when I chose a high mu toroid and wound with small wire, I could
not get the impedance of the primary up high enough to prevent a lot
of input current from being drawn by the primary when there was very
little current being drawn by the load on the secondary.
I'm not sure whether this is due to standby loss, or whether it just
means that my primary doesn't have enough reactance to prevent alot of
current from flowing into it when the output load is light.
Going down to .5 v AC RMS input makes the primary draw less current
for the same load on the output, but the turns ratio is 24x (240 to 1
instead of 10 to 1) higher and the secondary turns will have way to
much capacitance coupling between the turns themselves (self
It might be doable IF I could find a method of making a transformer
that minimizes capacitive couplings between the secondary windings by
mechanical design of the transformer.
My question to the group WAS:
Does anyone have any ideas regarding how to make such a transformer?
I know I can make a transformer that isolates the primary from the
secondary (in terms of capacitive coupling between the windings-I've
done it, it works great). But now I need to make a high turns ratio
secondary that doesn't loose all the power through self-capacitance
between the secondary windings.
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