Electronics > Beginners
Confused with about my new Lab/Bench PSU C.C. & C.V. Is it working correctly?
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IanB:

--- Quote from: james_s on August 10, 2018, 08:35:27 pm ---I would say that's splitting hairs. We all know that "constant voltage" means the voltage is constant over a range the device can achieve. Every real world device has limitations and boundaries.

--- End quote ---

That's quite right. But it's equally true of "constant current" mode. The current is also only constant over a range the device can achieve.

Whether you call it "constant current" or "current limited" is just a matter of perspective.
james_s:
Well yeah, I wasn't complaining about the use of the term constant current either. As with almost everything in life, it comes with a few strings attached and should not be taken in an absolutely literal sense.
piguy101:

--- Quote from: mikerj on August 10, 2018, 07:50:36 pm ---This PSU apparently has a button to switch from CV/CC mode which doesn't make a lot of sense.  The Circuit Specialists website doesn't explain things very well either:

Does this mean that the supply always uses the full output voltage compliance range with the button set to CC mode?

--- End quote ---

I have used this power supply in a lab before and I am not a fan of it. With the CC option off, the power supply outputs a constant voltage until it reaches the maximum current it can supply, just over 5 A. With the CC option on, the supply works as a typical CC/CV supply, but the buttons are used to set the current limit in steps of about 40 mA per press of the button. Of course, you have to short the output to see what the current limit is.  :palm:

I have no idea why you would ever want the CC option off. The first thing I always did when I turned on the supply was to enable the CC option, short the outputs and set my limit.

Anyways, the power supply is not great, but it has it two independent 30 V 5 A supplies that can be paralleled or put in series with the press of a button, which is nice.
rstofer:
Shorting the output to adjust the current limit is typical in these older designs and I don't care for it. 

I really like being able to set and read out the voltage and current settings like on the Rigol DP832.  Most, if not all, of the digitally controlled modern supplies have this feature.

Having a known current limit BEFORE you turn on the output seems like a very good idea.  I have used it to good advantage when I was bringing up a Z80 project that turned out to have an address conflict.  Limiting the current to 100 mA before turning on the voltage probably saved a couple of chips.
james_s:
I often just start the output current low and ease it up, stopping if it looks like it's rising to an unreasonable level while the voltage is still low.
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