How can this circuit improve 0...30V???

[cyw1984]

It is a 3 to 24 V linear power supply
how can this circuit improve 0...30V??? 

 

[cyw1984]

Also...If the Vref 0-5V replace 0-10V
how can i change the resistor and how to caculate???

thanks a lots

 

[audioguru2]

It is very similar to our 0V-30V project. It has a simple current limiter instead of an adjustable current regulator, and uses an extra transistor and resistor to turn on the output transistors. The opamp turns them off in this circuit.
It is good that it has a switched input voltage to avoid overheating at high current, low output voltage.

To use a 0V-10V reference instead of 0V-5V, simply make the 5k to 1k divider a 5k to 2k divider. ;D

 

[cyw1984]

It is very similar to our 0V-30V project. It has a simple current limiter instead of an adjustable current regulator, and uses an extra transistor and resistor to turn on the output transistors. The opamp turns them off in this circuit.
It is good that it has a switched input voltage to avoid overheating at high current, low output voltage.

To use a 0V-10V reference instead of 0V-5V, simply make the 5k to 1k divider a 5k to 2k divider. ;D

Vout = (R1+R2 / R1) * Vref

5k >>>> 4k
1k >>>> 2k
Is it OK??

 

[Staigen1]

Hi there, both of you

To use a 0V-10V reference instead of 0V-5V, simply make the 5k to 1k divider a 5k to 2k divider.

Wrong, if i do my math right, maybee i'm wrong, correct me if it is so! According to my math, the divider should be 2k to 1k, or, better up, 4k to 2k! Then you have 0 to 30 Volt out. Also, the resistor in the input rail should have a resistance about 1.3 Kohm. There are moore errors, the series pass transistors 2N3055 and 2N3053 dont have a resistance path from their bases to their emitters! Also, the 2N3904 can get a large negative voltage on the base! How are you planning to switch the input voltage to the rectifier? Observe, maybee you cant get 30 Volts out of this PSU, too low voltage on the input!

Also i belive the IC is wrong here, it can not swing to the negative rail on its input, and i'm not sure on the output, also, it's a doubble OP-Amp! A single would be better here, with offset null and working at the negative rail capabillities!

//Staigen

 

[Staigen1]

Oops, replying at the same time ;D. Hehe ;D

Also, if changing the IC, it must be a high voltage, tolerating moore than the voltage at pin 8!

//Staigen

 

[cyw1984]

Oops, replying at the same time ;D. Hehe ;D

Also, if changing the IC, it must be a high voltage, tolerating moore than the voltage at pin 8!

//Staigen

o...How to solve it???
which IC I should use??

Also ...how can it .....started voltage 3V change to 0V???
and can achieve to 30V

 

[Staigen1]

Hi again

o...How to solve it??? which IC I should use??

Well, wich IC was used in the improved 0 to 30V PSU here on this site? I belive it can handle inputs down to its negative rail, but i am not sure about its output, hey, audioguru, this i belive you know?

Also ...how can it .....started voltage 3V change to 0V???

Because the OP-Amp used in the original schematic not can handle inputs down to its negative rail, the output can not go down to zero! But if you change the OP-Amp to one that can do that, the output also can go down to zero, but you also need offset null capabilly to achieve this with some accuracy. The OP-Amp also have to have capabillities to work near the negative rail on the output, otherwise the output of the PSU will not go down to zero.

and can achieve to 30V

By having a tranny, rectifier and smoothing cap giving some voltages moore than 30 volts when loaded at maximum.

//Staigen