Laboratory power supply 0-30V 0-10A

I put this power supply together and it works. But after some modifications, the assembly according to this scheme is ok until the transformer windings are switched (120 Watt 2 X 15V toroid), ZD2 overheating (voltage at C10 - 20V). I made the transformer winding switching system on the LM 358, power supply from additional winding 15V, intended for a four-digit double A / V meter from Ali. Now it works without a problem, only there is a problem with resetting the ammeter, after starting it shows 32 mA. I used the same meters in my colleague's eurotips ETL power supply, they work without any problems in it. When comparing both of these power supplies, I bet on ETL.

karel21 wrote:

it is ok until the transformer windings are switched (toroid 120 W 2 X 15V), ZD2 overheating took place

Because you misread the diagram. Take a close look at it - to which point is the diode connected?
The voltage switching only applies to the power supply circuit, not the zener diode.

That's right, I read the diagram correctly, also a correctly made PCB. The power supply for switching the transformer windings, the relay and the power supply 723 are connected to the first winding of the AC 15V transformer, permanently, through a rectifier diode D2 1N4007. Despite this, the DZ18V burned, I checked the board and components many times until I was bored, I had to make a mistake, but I missed it. I finally etched the new plate and it works fine.

tanks for your Practical schematic...but a qustion:How can i upgrade trans 2x15 to 2x23? if can use that voltage than need to change any Piece of schematic?
specially part of R5 and R23 OR R13 and R26?
tanks

that schematic is Upgrated to 0-50 volt and sam curent..
foe any one need it.

sahamipoor wrote:

How can I upgrade trans 2x15 to 2x23?

Replace the transformer with a suitable one?

398216 Usunięty wrote:

sahamipoor wrote:

How can I upgrade trans 2x15 to 2x23?

Replace the transformer with a suitable one?

replase it with another trans 10 amp...

Hi guys..
I made this board and I'm very satisfied with it and it's function...
But the Instantaneous flow starting is veryyy high, after current lemited Get started!!
At the lowest output current mode (about 10ma), By doing short circuit It do spark strongly!!!than curren limeted worked!!!
why??? how can put on the Short circuit protector?

Jawi_P wrote:

eurotips wrote:

one capacitor with a capacity of 100mF is a bad idea, a better solution is 10x 10mF and a dedicated pcb only underneath it with holes for a solid mounting.

And soft-start will be mandatory, not optional.
The second thing is that by roughly calculating the filter capacity for a maximum current of 10A, and the ripple level of 2V, I ended up with 0.05F. And that's a lot already.
I would reduce C9 as much as possible and / or use a current source at the output to discharge this C.
Since there is D3, the fuse at the output would also be useful?

c9 (100 mf 63v) overheats when there is a 12v load on the output.
I changed capacitors twice.
now i have 100v 33mf.
like no problem. working

I thought while doing my power supply so recently that the use of the OP07 amplifier is obsolete. But this system is a real prehistory
I have some 723 left in different housings from the period when a lot of it was put into the CB radio power supplies

needs a simple black and white pdf mirroed pcb atwork,the one shown here is crap for toner transfer!

quadzillatech wrote:

I need a simple black and white pcb mirroring pdf file.

Install Sprint-Layout 6.0 Viewer free and print.

quadzillatech wrote:

I need a simple black and white pcb mirroring pdf file.

Or maybe let's order a few of these pcb - I will buy 2 pieces myself.

A very big problem in this project is:
In high voltage-20v-, the short circuit current is very high at the first moment of probes stick together.. even, when the current volume is completely closed on low current.
any one had selution for this?

Any reason why current adjust potentiometer is logarithmic?