lm317 cant changing adjust pin voltage

[qwertyqwq]

Is goal to have an LM317 with output voltage controlled by a control voltage with a current limit circuit?
If so there are easier ways to do that.

Yeah. All of them will control by ucontroller. Everthing ready except circuit

 

[alec_t]

Try this simplified arrangement :-

 

[crutschow]

Note that the current limit will not work when the output gets below 1.25V (e.g. a short).

 

[qwertyqwq]

Try this simplified arrangement :-
View attachment 124263

Why did you use pulse sources ? I planed to control lm317 with analog voltages. Is that matter ?

 

[alec_t]

Why did you use pulse sources ?

To see what happens when the inputs change. It's a standard simulation procedure.

 

[qwertyqwq]

Try this simplified arrangement :-
View attachment 124263

Working.. Also in simulation , also in appliance. Many Thanks.
But another problem is voltage drop of output. For example oıtput without load there is 24v. On 33ohm load , it drops to 14 v. I know this happens because of the no feedback. Although i change control voltage , output cant move back to 24v. Only goes about 20v.
What can i do for that issue ?

 

[alec_t]

Did you measure the regulator input voltage when the load was 33 Ohms?
Is your circuit built on a breadboard?

 

[qwertyqwq]

Did you measure the regulator input voltage when the load was 33 Ohms?
Is your circuit built on a breadboard?

Yeah your right. Input is fallin about 25v. so 22-23v output becomes normal. I didnt notice input is falling ! It musnt be fall like that. Because i have 20,5v 11amps transformer. Huge transformer. Shouldnt expect voltage drop on input cause of that huge transformer.

And yes im currently tring on breadboard. First circuit was on printed board.

 

[qwertyqwq]

Amazon.com

Transformer is like that one. Seperated two 115v primar winding. Out is 20,5v 11amps. I tied series of primaries so its working on 230 v main voltage.

 

[alec_t]

Transformer is like that one. Seperated two 115v primar winding. Out is 20,5v 11amps.

?? The transformer in the link has a 30V output rating.
A 20V transformer has a peak ouput voltage of 20*1.414 = 28V. A bridge rectifier will reduce that to about 26V under load.
Breadboards are not designed to handle high currents and their contact strips do not provide reliable connections. Some voltage drop might be experienced there.

 

[crutschow]

What is the size of the filter capacitor at the rectifier output?

 

[qwertyqwq]

The transformer in the link has a 30V output rating.

Yup i know. Caıse of that i said that;sorry couldnt find my transformer on internet.

Transformer is like that one.

A bridge rectifier will reduce that to about 26V under load.

And yeah i forgot to calculate recrifier forward voltage drop.

After some arrengment i ll build circuit on printed board.

Many thanks for informations. Because of that i really love this forum. experiences talks , not assumptions. You guys doing great jobs.

 

[qwertyqwq]

What is the size of the filter capacitor at the rectifier output?

Its a 1mf 30v cap. Also ,as datasheet says, there is a 100nf cap on input of the refulator. It connected as close as possible.