EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: essele on January 05, 2019, 05:04:37 pm
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Hi,
I managed to get myself a Power Designs model 2005 after seeing Dave's video on it ... absolutely beautiful!
Once I cleaned the contacts and experimented with the jumpers I've got it nicely calibrated, all seems to work pretty well.
The only issue I've seen is that it's quite slow to settle, especially when I switch between ranges, but also when I make relatively coarse changes, if I go from 20.000v to 10.000v for example, it hits about 10.030 within a second or two, then spends the next 30 seconds slowly settling down to 10.000. Once it's settled it's pretty solid usually only see a variation of a few uV on my 34470.
Is that expected behaviour, or is it indicative of a problem?
Cheers,
Lee.
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My 2005 drops from 20 to 10 volts to within a couple of mV in a few seconds. Then it slowly drops for about 15 seconds before I would consider it stable.
I have a couple of HP precision power supplies that also take several seconds to settle down.
Don't really know if it is all expected, but there are often fairly large capacitors hanging across the output.
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It looks to me like that would be caused by uneven heating of the differential transistor pair when they are momentarily unbalanced. The time constant is about right for this. There are some circuit design tricks to minimize it but Power Designs did not use them.
Monolithic differential pairs settle much faster (microseconds) because the transistors are in close proximity on the same piece of silicon.
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I don't have a PD2005, but my 2005A doesn't exhibit this behavior. Is your heater operating normally?
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I don't have a PD2005, but my 2005A doesn't exhibit this behavior. Is your heater operating normally?
The 2005A uses a very different circuit.