how to remove current adjust part

[root2hell]

i have an schematic which has 2mA to 2 A current adjustable and 0-30V voltage adjustable. but i want to remove current adjustable part can anybody help me what arts i need to remove to make it 0-30V regulated power supply.
thanks!!!

 

[KlausST]

Hi,

Just adjust it it to 2A. ;-)

R7 is the shunt, via R21 to U3, this is the regulator Opamp. R17 and P2 build the reference input.
Controlled via D9.

This is the whole current regulatin circuit.

Klaus

 

[Audioguru]

That schematic has many faults. It does not produce 30V at 3A. Many of its parts are overloaded so it is not reliable. I fixed it in the forum at Electronics-Lab.
The current regulation in the fixed version protects the circuit from being destroyed if the output is shorted or if the load current is higher than 3A.

 

[root2hell]

In theoretical description of the above schematic it is said that the U3 opamp gives a gain of 3X but i didn't get how it will give gain of 3X.
and when i put probe i didn't get output=3X(input).

 

[Audioguru]

The new schematic you posted does not have a U3 opamp. It also does not have any current limiting or regulation so it will make a spectacular fire when it is overloaded.

The original schematic has U3 as its current regulator. It has no DC negative feedback so its voltage gain is about 200,000 times.
U3 compares the voltage across the current sensing resistor R7 with the voltage at the current setting pot P2. When the voltage created by R7 exceeds the voltage on the pot then the output of U3 drops and D9 causes the output voltage of the project to drop until the voltages at U3 inputs are the same.

- - - Updated - - -

I looked at the original project at Electronics-lab. It says opamp U2 (not U3) has a voltage gain of about 3X.
The voltage gain is 1 + (R12/R11). R12 is 56k and R11 is 27k so the voltage gain of the entire output amplifier is 3.074 times.

Opamp U8 in your new schematic with the driver and output transistors has a voltage gain of 2X. The output voltage of the project will be 11.2V x 2= 22.4V.