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Lab Power Supply - The Lost Current
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Damianos:
I lost the communication!
If someone gives me an algorithm, to decode the messages, it may be reestablished!
TimNJ:
Try a "diode-OR" to switch between the CV and CC control loops. This is a common and effective way to implement constant current limiting on a "normally CV" power supply.

Check out the attached schematic of an HP6214A lab power supply.

Also check out this Keysight article: http://powersupply.blogs.keysight.com/2012/07/how-does-power-supply-regulate-its.html



xavier60:
There is a 5W 0.68 ohm resistor on the regulator PCB. I can't see the marking of the resistor next to it? Are these the shunt resistors?
radoczi94:

--- Quote from: TimNJ on February 02, 2018, 05:16:56 am ---Try a "diode-OR" to switch between the CV and CC control loops. This is a common and effective way to implement constant current limiting on a "normally CV" power supply.

Check out the attached schematic of an HP6214A lab power supply.

Also check out this Keysight article: http://powersupply.blogs.keysight.com/2012/07/how-does-power-supply-regulate-its.html





--- End quote ---

Thanks, will try it.

Edit: One thing came into my mind. I am not shure, that I can put a diode in series with the CV opamp. What I could do is to move the diode on the CV opamp output (D7) and tie it's anode to the driver transistors' (Q4) base.


--- Quote from: xavier60 on February 02, 2018, 12:01:13 pm ---There is a 5W 0.68 ohm resistor on the regulator PCB. I can't see the marking of the resistor next to it? Are these the shunt resistors?

--- End quote ---
Yes, it was in there, when I took the picture. When I put those 0,68R resistors,then I realised, that the "missing" 2 amps is more or less linear with the output load current.
xavier60:
Don't modify it until you have found a definite reason for the problems. Have you checked for oscillations?
When you checked the regulator PCB for a possible short bypassing the shunt, did you have all of the wires connected?
 

--- Quote from: radoczi94 on February 02, 2018, 09:51:56 pm ---
--- Quote from: TimNJ on February 02, 2018, 05:16:56 am ---Try a "diode-OR" to switch between the CV and CC control loops. This is a common and effective way to implement constant current limiting on a "normally CV" power supply.

Check out the attached schematic of an HP6214A lab power supply.

Also check out this Keysight article: http://powersupply.blogs.keysight.com/2012/07/how-does-power-supply-regulate-its.html





--- End quote ---

Thanks, will try it.

Edit: One thing came into my mind. I am not shure, that I can put a diode in series with the CV opamp. What I could do is to move the diode on the CV opamp output (D7) and tie it's anode to the driver transistors' (Q4) base.


--- Quote from: xavier60 on February 02, 2018, 12:01:13 pm ---There is a 5W 0.68 ohm resistor on the regulator PCB. I can't see the marking of the resistor next to it? Are these the shunt resistors?

--- End quote ---
Yes, it was in there, when I took the picture. When I put those 0,68R resistors,then I realised, that the "missing" 2 amps is more or less linear with the output load current.

--- End quote ---
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