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From: John Popelish
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X-Mailer: Mozilla 4.7 [en] (Win98; U)
Subject: Re: Inductor used in 110v to 15v
References: <3DE81288.C85DE010@rica.net> <3DE82608.E96CD844@rica.net>
Date: Fri, 29 Nov 2002 04:32:58 GMT
NNTP-Posting-Date: Thu, 28 Nov 2002 23:32:58 EST
> John, you set me on my path. Thank you. But after reading the above article I came away with a few questions that are probably
> more trivial than anything. What would happen to this circuit if we could increase the frequency of the AC from 60Hz? And, what is
> the point to the resistor in series with the DC circuit? Dave
The resistor in those schematics represents the load connected to the
output of the rectifiers. RL means load resistor. It is just
symbolic of some circuit that passes current in response to an applied
When the frequency gets higher, less core material is needed to make a
practical transformer. This is how they can get a few hundred watts
out of a golf ball sized transformer in a switching supply, where the
frequency is produced by transistors pulsing on and off at 10s of
thousands of cycles per second. If the frequency gets up into the
million cycles per second, it begins to get practical to make air core
transformers. Tesla coils are just big air core step up transformers
with loose coupling between primary and secondary windings. (Do a
google search for tesla coil and you will see how they are made.)
But for line frequency transformers, there is no practical substitute
for silicon steel laminated cores, either punched E and I stacks or U
I stacks, ot tape wound toroidal cores. ebay and surplus distributors
are good sources for transformers larger than a few VA.
By the way, adding the word, turorial to almost any noun is a good way
to find information on devices and circuits from Google.
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