Electronics > Projects, Designs, and Technical Stuff
Non-linear CV/CC control in schematic
xavier60:
I'm not certain if the idea I mentioned will get t all the way down to 0V output because of the way the voltage error amp is designed in the LM723.
There needs to be enough voltage applied to pin 4 to keep Q13 turned on inside the IC but the Comp pin 13 can't pull much lower than pin 4.
EDIT: I had the pin numbers all wrong from the data sheet.
Silver_Pharaoh:
--- Quote from: xavier60 on March 03, 2019, 05:43:54 pm ---I'm not certain if the idea I mentioned will get t all the way down to 0V output because of the way the voltage error amp is designed in the LM723.
There needs to be enough voltage applied to pin 2 to keep Q13 turned on inside the IC but the Comp pin 9 can't pull much lower than pin 2.
--- End quote ---
Doesn't need to be perfect, I don't think I'll need anything lower than 1V. I was only asking if I need to test something low voltage like an LED or something :)
I think I'm getting somewhere though, I modified the schematic again and moved the volt adjust pot over to where I think you were telling me to move it.
It seems pretty linear, each 0.1 increase or decrease in the pot turn raises or lowers Vout by ~2V. That's not too bad I think.
I've attached the latest revision below.
xavier60:
Notice that I had to correct the pin numbers in post #15. I keep forgetting that there a 2 packages with different pin outs.
xavier60:
It will need a resistor from Vref to the Inv pin to keep some minimum voltage on it but I'm having trouble figuring out how much it needs.
Silver_Pharaoh:
--- Quote from: xavier60 on March 03, 2019, 05:54:17 pm ---Notice that I had to correct the pin numbers in post #15. I keep forgetting that there a 2 packages with different pin outs.
--- End quote ---
Haha I see! I better pay attention when I'm ordering the LM723.
Wonder why they do that? wouldn't it make more sense to keep the pinout the same?
I think the circuit is pretty much done. I'm happy with it anyway. I've attached it to the post.
Can anyone see any issues with it? I added in the resistor wattages as well. They should be good I think.
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