Hi guys,
The circuit diagram of the laboratory power supply:

https://elektrotanya.com/conrad_ps_302_a.pdf/download.html

In parallel to the green LED D107 the following components : D106 1N4148, D108 1N4002, C104 100uF 16V, R106 3K3. What they are for?
I want to make a LPS for otput 0-50V , 0-0.5 A . So examining the circuit diagram

 

One LED is to indicate when in constant voltage mode. The other LED is to indicate constant current mode.

 

I do know what for are those two LED's.
What for are those : D106 1N4148, D108 1N4002, C104 100uF 16V, R106 3K3 ?

 

They are there to drive the LEDs.

 

Whilst building a power supply is a laudable task, and no doubt you would gain further insight into electronics as a result – I doubt you could buy the separate components for the price of this finished unit (and many similar that are available).

https://www.ebay.co.uk/itm/33482637...//Hfj02VD6b38R6PgaRKLyWiil|tkp:Bk9SR6KN3b36YQ

 

Oh, that one’s not working – try this one:-

https://www.ebay.co.uk/itm/16579129...4qIRUX7SVhAkbrirPQuRkjlHF7|tkp:Bk9SR6iN3b36YQ

 

One thing about power supplies, though, is that most of the expensive components can be scrounged from obsolete electronics. Power transformer, heat sink, filter caps, pass transistors. Motorola's MC1466 regulator chip has been out of production a long time, but the application note is still relevant. The LM10CH app notes include a regulator circuit which could probably substitute for the MC1466.

 

Thank you for replies, guys

I had some practic with switch mode PS Hyelec 50V 5A, it's appearance is like that with red LED display:

https://www.diverseelectronics.com/upload/documents/Mastech-HY3003.pdf

Bad impressions, really- output voltage is not quite stable, case is unsteady, made of thin tin, output pins inconvienent, etc. Looked inside-a daughter PCB fixed with cable ties and hot glue... It seems it's schematics was simplified dramatically, they counted on small signal trafos even. Finally, it broke down, a SMD opamp 324 was found dead. I repaired the PS and sold it for a half price, finally... Happy end, indeed.
And , i did realized, i don't need such a big power PS . A linear PS is much more useful, too.
I already have a lot of components , taken from old electronics- transformer with secondaries 45V 1A, 8V 4A, 12V 0.2A, filter caps, opamps 741, 324, 4558,etc, reference 341, connection terminals of good quality etc . Main expenses is my work