Michael Edmiston's idea of charging capacitors in parallel and then
discharging them in series is also called a "Marx Generator", or a "Marx
Bank", "Marx Capacitor Bank," etc.
"A Marx Generator is a clever way of charging a number of capacitors in
parallel, then discharging them in series. Originally described by E. Marx
in 1924, Marx generators are probably the most common way of generating
high voltage impulses for testing when the voltage level required is
higher than available charging supply voltages."
Steven T. Ratliff
Associate Professor of Physics
Northwestern College
3003 Snelling Ave. N.
St. Paul, MN 55113-1598
U. S. A.
Internet: str@nwc.edu (or stratliff@nwc.edu)
Michael Edmiston <edmiston@BLUFFTON.EDU>
Sent by: "phys-l@lists.nau.edu: Forum for Physics Educators" <PHYS-L
12/07/00 08:40 AM
Please respond to "phys-l@lists.nau.edu: Forum for Physics Educators"
To: PHYS-L@lists.nau.edu
cc:
Subject: Re: transformers
Sorry if I am beating something to death, but I thought of an interesting
type of DC-to-DC step-up "power-supply" that helps explain how this can be
done, and it is an example that is pretty simple to understand.
I have a digital camera that uses 4 AA batteries in series to produce
about
6 volts. I use rechargeable NiMH batteries. I have a battery charger
than
can charge one or two or three or four AA batteries in parallel. (The
charger supplies about 1.5 volts to each of four battery chambers.) Let's
assume I charge all four batteries at once (charging in parallel from a
1.5-volt supply) then I use them in my camera (in series to provide 6
volts).
In this example I am manually converting the power-storage components
(rechargeable batteries) from parallel charging to series discharging with
a
cycle time of about one day. I am doing a DC-DC conversion from 1.5 volts
to 6 volts.
Now imagine a power supply in which the power-storage components are
capacitors, and the parallel-charging/series-discharging is operated
electronically (by an integrated circuit) at tens-of-kHz frequency.
The differences between the battery example (which many of us have done)
and
the power-supply example (which might seem somewhat exotic) are rather
slight... (1) capacitors instead of batteries, (2) electronic
reconfiguration rather than manual, (3) reconfiguration periods of
microseconds rather than hours.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817