I need to use LM723 and Tip-31c to build a voltage-regulator and current-limit c

Question

I need to use LM723 and Tip-31c to build a voltage-regulator and current-limit circuit. the output voltage is 7V and the current through the load should be under 1A or it will shut down.

this is what i bulid

ignore the values on the graph,i use

R1 and R3 = 22 ohms, R2 = 1k, Rsc = 0.68 ohms R7 = 1K ohms. From LM 723 data sheet, there is a formula to calculate R1 , R2 and R3, also shows Vref = 7.15V.

so, I connect my circuit to an AC power supply, then I test my pin 10 voltage that shows 6.20V,but the pin 2,3,4,5 shows that voltage is 6.77, I don't know why that happens. Also, when I connect to a load and let the current flow, then the systerm immidiatly shut down, and no matter what resisitor i put in and how much cureent is go through. That's another problem I don't know why.

next graph shows and example of the LM723 circuit with an external transistor.

Please give me some suggestions about my circuit, Thank You!!!

Explanation / Answer

My suggestion to your problem is as below,

From the data you have provided, I can understad that, from terminal 2 to terminal Vout there is a current flow. This is because, the voltage at terminal 2 is 6.77 and voltage at Vout is 6.2V from your observation. Thus the current is going out of the base terminal of the transistor and to me this points out that the current limit is not working.

So, my suggestion is you try a differnt LM723 IC. By replacing with the new LM723, you would make the current limit to work fine and thus the output would regulate at 7V.

Also, make sure that you observe the voltage at terminal 12 as well. If this voltage is going negative, (because of some issue with rectifier) then also you would face this kind of problem of output not regulating.

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