[0-30 Vdc Stabilized Power Supply]

Prior to the current limit threshold, U3 is "acting" like a comparator, sitting at the positive rail waiting for the voltage across R7 to increase. Unless someone wanted to use the supply as a "regulated current source" whiles it's in current limit, does current regulation matter?? Not that it isn't a good idea, but I can't think of a reason why a "typical hobbyist" would care.

Agree. I want to make it a CV/CC PSU.

[0-30 Vdc Stabilized Power Supply]

R8 and C4 are a filter to remove high frequency noise from the D8 reference voltage circuit. R9 isolates C4 so that D9 can reduce the voltage of the project quickly when current regulation needs it to be reduced.

Since the D8 ref voltage is also used in U3, why don't we put a filter before U3-P3?

[0-30 Vdc Stabilized Power Supply]

Yes, then Q3 would never turn off. The output of the opamp U3 is a darlington transistor and its max voltage is about 1.5V lower than the positive supply.

This makes sense, thanks :)

[0-30 Vdc Stabilized Power Supply]

C4 has NO affect on U3 until you hit current limit, at which point U3 turns on just hard enough to reduce (clamp) the voltage at U2-pin3 such that the drop across R7 becomes small enough to "release" U3. Having R9 will slow down the discharge of C4, not speed it up. Until you hit current limit, U3's output is at the positive rail... so it will not oscillate. In the end R9 doesn't really do much...

indulis,

R9 slows down the discharge of C4, but it allows the U2-pin3 to be pulled down faster. Without R9, the circuit has to wait until C4 is fully discharged before entering current limit mode.

[0-30 Vdc Stabilized Power Supply]

Yes it would.

Will the circuit run without those components in place... yes, but under certain conditions, it might be possible to "flame" some components without it.

R19?? Did you mean R9?

I mean R19

[0-30 Vdc Stabilized Power Supply]

If the project tried to go quickly to a low voltage then the emitter-base junction of Q2 would break down at a reverse bias of about 6V. R15 limits its avalanche breakdown current.

Wouldn't D10 clamp the E-B junction and R16 voltage to 0.7V if there is reverse bias?

[0-30 Vdc Stabilized Power Supply]

4. Can I connect output(pin6) of U2 to base of Q2 (bypass R15)? If not, why?

Let me correct my question. My question is:
If I do not need the protection circuit consists of D10, R15 and Q1, can I drive Q2 directly with output of U2?

[0-30 Vdc Stabilized Power Supply]

May I remove R19? Would this cause an problem?

[0-30 Vdc Stabilized Power Supply]

hi AG,

1. How to decide the value of R9? Why don't we use 10K or 470R?
2. What's the purpose of C5? How to calculate the value?
3. Is C9 used to improve the stability of U2?
4. Can I connect output(pin6) of U2 to base of Q2 (bypass R15)? If not, why?
5. If the system should be grounded, which part of the circuit should connect to ground as well?