EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: djnz on January 04, 2017, 08:31:39 pm
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A lab power supply that I acquired recently seems to have a problem. Whatever may the set output voltage be, when its output is enabled, it jumps first to about 0.65V and and then goes to the set value. If the set output voltage is greater than 0.65V, I don't see this as an issue at all, but if the set output voltage is smaller than 0.65V, this becomes a case of overshoot. I have attached an oscilloscope trace photograph taken when the output voltage was set to 0.5V.
I was wondering how much of a problem this really is.
1. In which cases could this behavior actually be an issue? Which components / circuits could be fried or adversely affected due to this? Would it actually matter if it's fixed or not?
2. What could be the reason for this? From the 0.65V value, I suspect there is a PN jn drop involved. How could I go about investigating / fixing this?
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It might be just the way the power supply was designed, not a problem, are you using a crappy power supply or a good quality one?
other than that, did you notice any instability with various loads?
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Haven't noticed any instability / other problems yet, though I have only drawn up to 1A from it and it can supply 3A (30V 3A X 2ch, 5V 3A X 1ch). I was actually testing it for assessing its quality. So far, its meter has been pretty accurate and it has stuff like has remote sensing, USB programming (SCPI) so it's definitely not trying the cheapest. It's an ITech supply, also rebadged and sold by BK Precision, so I expect it to be of fairly good quality.
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Haven't noticed any instability / other problems yet, though I have only drawn up to 1A from it and it can supply 3A (30V 3A X 2ch, 5V 3A X 1ch). I was actually testing it for assessing its quality. So far, its meter has been pretty accurate and it has stuff like has remote sensing, USB programming (SCPI) so it's definitely not trying the cheapest. It's an ITech supply, also rebadged and sold by BK Precision, so I expect it to be of fairly good quality.
Try to add about 10uF capacitor at the output, and put a 0.5A+ load on it and see if the overshoot still happens.