You need AC for a passive transformer to work (actually you need a magnetic
field that changes over time). DC voltage cannot be transformed by a
passive transformer. You have to chop it up, transform the chopped up
waveform, and then smooth it out again. In other words it takes an active
So are they different? Yes in that a DC transformer doesn't really exist.
Charles Perry P.E.
That is even more dangerous.
Do you know any thing about HV.
Do you know how far a spark can jump.
Do you understand the effect of a sharp point on the high voltage end.
In any case, work with one hand in your pocket if you will not be disswaded.
If you have to ask questions about HV DC that means you do not have enough
knowledge to work with it.
Nothing substitutes for a couple of years of apprenticship where you learn
the things not in the books.
So now you can die by direct electrocution or when one of the caps
If you are unfamiliar with the specifications for HV rectifiers, what
makes you believe that you know what you are doing with caps?
Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com
note to spammers: a Washington State resident
Sorry Chuck you are wrong on that one.
DC transformers do exist and they are used in most satelites.
They use two cores and require an energizing source and are used to measure
They are some times refered to as Mag Amps.
You will find them explained in Rotors.
I also invented a dc transformer which is extremely accurate some years ago.
I can acturally measure with an accuracy of about 1 part per million or even
The higher the current, the more accureate it is.
The offset is fixed, no matter what the current is.
I delivered a paper on it at the IEEE but it was a bit advanced and I do not
think any one even understood what was going on.
It uses a single core.
Basically the DC drives a very narrow loop material way into saturation.
I mean like a thousand times the width of the hysterieses loop.
Now a voltage is applied to the search coil so as to bring the core out of
When the core comes out of saturation and the core travels back up the loop
there is a voltage pulse out of the sense loop. This pulse then is a
measure of how deeply into saturation the core was and a measurement of the
Because the saturated state of the core is so large compared to the loop
width, the measurement can be very accurate.
I actually build and tested the device.
Advantage is just one core and extreme accuracy.
in article email@example.com, Charles Perry at
firstname.lastname@example.org wrote on 9/17/04 5:16 AM:
There is a fundamental problem to assigning passive or active attributes to
a device. To me, there is nothing active about a silicon diode sitting on
the table. Nevertheless, by driving it with an ac signal, it can become a
parametric oscillator. By driving a tunnel (Esaki) diode with dc, it can do
all kinds of interesting things.
Devices do not produce energy although they do transform it.
The main distinction should be between linear and nonlinear devices.
I have a 5000 volt meter.
It is a direct reading meter and is not an electronic one.
It reads 5000 volts directly and does not require any special probes.
The interesting thing about it is that if the conditions are right the
needle sticks to the glass.
I used it when I was designing 28 to 5000 volt isolated, regulated, power
supplies that could fit into a 20 cigarette package.
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