BTW, it's the 100k leakage resistance that LT's model leaves out that screws things up.
I'd go with what Kemet think. They made the damn things. I assume they must have measured some.
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
On Wednesday, June 20, 2012 10:37:46 AM UTC-7, Tim Wescott wrote: [about long integration of a DC input]
So, feed your DC suspect into an integrator (1Mohm resistor, op amp with 1 uF film capacitor in negative feedback, + feedback to a DC offset through a second 1M ohm resistor); if this isn't slow enough, divide down the DC by a factor of 10/100/1000 with a two-resistor voltage divider.
You can get hours to days of delay, and it doesn't take any exotic parts values.
m t t f I h p
What the heck is "DC finding"? Don't most people use DC restore circuits in= that situation?
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Or cheat: Hang a uC in there that has an ADC and maybe a DAC (or use PWM for that). Sample regularly and integrate up to wazoo. Then pack it all into a blue, green oder yellow can and write 100,000,000uF on there :-)
My newsreader window cut the subject line at the last three characters so it read "So, where's the cat" ...
-- Regards, Joerg http://www.analogconsultants.com/
Shouldn't that be "grün or gelb"?
;-)
-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
:-)
I always liked the blue-metallic of Philips electrolytics.
-- Regards, Joerg http://www.analogconsultants.com/
The volume of an electrolytic cap tends to track C*V, which is why you can store more joules per volume in higher voltage caps.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
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You'll need a really good ADC to see small voltages. Dithering can at least take out the quantization step errors.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
As I recall, originated by Mullard, before the Philips takeover.
Used to be considered very reliable. Things have moved on.
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
Meow.
I have a microprocessor on the board, which has a DAC. I was tempted -- but the customer was already leery of changes to their circuit, and the particular microprocessor was swapped in after that part of the circuit was done, so I forgot to think about what I could do with DACs.
-- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
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Well, you can get pretty good 24bit conversion these days. That's a lot of dynamic range. Best is to do that differentially.
-- Regards, Joerg http://www.analogconsultants.com/
I weas involved in a similar recently. Too late to change it all out. They were concerned that it ain't safe because the uC can croak. Very understandable, and I would not do it either. But what I'd like to do on the next rev is to plop down one uC per function, running totally autonomous so that it will not even notice if the big processor croaks. All each one would do is a free-run internal oscillator, ADC ... crunch, average, crunch some more, spit DC average out as ... a DC level. Or as an alert signal if desired.
-- Regards, Joerg http://www.analogconsultants.com/
That doesn't really go for ceramic caps. Try to find the stored energy density of this puppy at high voltage:
But it has to be made from the good stuff, not Y5V or Z5U.
-- Regards, Joerg http://www.analogconsultants.com/
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