Re: Where are all the ESR meters?
- From: Jim Thompson <To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx>
- Date: Mon, 23 Jul 2007 06:43:21 -0700
On Mon, 23 Jul 2007 05:50:10 -0700, Winfield <winfieldhill@xxxxxxxxx>
wrote:
[snip]
A better idea, I think, is to use a proper higher-impedance
current source, and drive with a 100kHz sine wave, thereby
greatly reducing the ESL problem, which can otherwise be a
killer for the 1 to 30 milliohm region. Using a sine wave
also means the measured ESR can be compared with laboratory
meter readings. Otherwise, how would one compare sets of
square-wave readings with accurate lab instrument readings?
I'm with you on that, even the frequency.
I'm thinking of using a 2-volt peak sine wave with a 200-ohm
resistor (10mA peak test current) delivered from a rail-to-
rail opamp with a slew rate exceeding say 2V/us. I'll break
the resistor into three parts and add two sets of protection
diodes to the rails. The outermost resistor can be a 100-ohm
10-watt high-thermal-mass part to discharge the capacitors.
I've been thinking along the lines of an AC _current_source_, and
using the cap UT as the filter to keep it queued. Then you get a
linear reading of ESR.
But I've been lacking time to put pencil to paper... I'm up to my
gills in (paying) projects... and, in my business, one must make money
while it's available ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
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- References:
- Re: Where are all the ESR meters?
- From: John Larkin
- Re: Where are all the ESR meters?
- From: Winfield
- Re: Where are all the ESR meters?
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- Re: Where are all the ESR meters?
- From: Winfield
- Re: Where are all the ESR meters?
- From: Jim Thompson
- Re: Where are all the ESR meters?
- From: Fred Bloggs
- Re: Where are all the ESR meters?
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- Re: Where are all the ESR meters?
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