Can We Connect the 12V and 5V Outputs From ATX PSU In Series To Give 17V-18V?

The PCBWay 0-30V 0-10A Bench Power Supply project that I built requires two input voltage supplies, one around 17V and the other 34V. I tried using two ATX PSU in series in the previous video, giving 12V and 24V ,and tried to modify the circuit to work but the voltage was not high enough for the circuit to operate correctly. In the comments that followed a subscriber said I should connect the 5V and 12V on each ATX power supply in series, giving 17V from each PSU. Is this even possible? Well I don't know but it sounds interesting so let's see if we can do it

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The 0-30V 0-10A PSU Project

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[andymouse]

I learnt a lot as my mate gave me a clue when he said "people forget that the ATX supplies are high current 5V power supplies first and 12V and 3.3V second and are hard to mod " great interesting series...cheers.

[tamastorontali]

Dear Richard, Your videos are very good, informative and objective, I learn a lot from you. Please make a video where you also use the oscilloscope for troubleshooting, not just the multimeter as usual, if you have the means. Thanks a lot for your hard work!

[davet]

Great stuff . This is all about learning stuff .Set off on a course and see where it leads, learning on the way .If guys are looking for a simple PSU project then this is not it BUT a great educational project for all.

[kriswillems]

You could let the ATX supply regulate the 12V line at 17V by adding a voltage divider in the 3.3V feedback loop.

[davidhollfelder]

I use HP DPS-600pb server power supplies for my LiPo battery chargers, and ham radios.
These are rated at about 40A, are quite inexpensive and still available.
There is lots of mod info for these PSUs on the net, including adjusting the output using pots or resistors, etc.

[GapRecordingsNamibia]

Hi Richard, I would say, yes, the "old mixer" with the toroid would be a good

[mikepanchaud]

How about using 2 x 19 volt laptop chargers ? There must be loads of unused ones in flea markets. The outputs are isolated from each other, they should be good for about 3 amps, which is enough for anybody!

[fayyazbahrami]

old atx have two turns for 5 v then added extra 3 turns for 12 v, for your use you have to rewind secondary or change 1 amp diods on -12 v then you have 24v and change feedback to lower output

[jndominica]

How does a psu regulate the individual voltages if it only monitors 3.3V and has one transformer? Suppose I connect a motor to 12V and nothing to 3.3.

[waiduxg]

there is two types of transformer's used in old psu's 33 and 35, on your video is 33, on other psu I think it is 35 and I think they might be wired diferently so you may try this thing with another one...

[nobeme]

I live in Canada I removed a microwave transformer I want to disassembled it and make it into a isolation transformer 120-volt in 120 out so one of the windings is okay with the other one I have to modify I'm thinking 120 winding should give me my 120 v am I correct to see what you think thank you in advance for an answer as always enjoy all your videos...

[wobbiewall]

I'm thinking R6 is providing too much feedback when you try to run with the 212V in series.

[theQdomain]

Richard is there a way to change the reference voltage on the feedback circuit of the power supply so it will output 15 instead of 12 volts. I seem to remember one of your videos talking about changing the voltage on a switch mode power supply by adjusting the voltage divider that sets the reference on (not sure) LM317. I imagine that the Pam controller will just increase the pulse with a bit and result in a higher output voltage. I could be way of base here and you may have already ruled that out. Love the channel. Keep up the good work.

[Pixelwaster]

here is a page (in russian) to a list of schematics to a bunch of computer PSU. Secret code: sector biz us slash docs slashed power_supply_schematics slashing powe_supply_schematics dott phtml. You can get less of a voltage drop across the 2N3055s by using a smaller emitter balancing resistor. I've used 0.1 Ohms but I have seen commercial supplies use 0.05 Ohms. I have a bucket of 3055s (literally sold to me in a bucket) and a similar amount of RCA house numbered parts. Been fixing and nuilding linear supplies since the 90s. The 2N3773 is a nice upgrade. Two 3773 for three 3055.

[perhagensen]

What if you connected 3 ATX power supply in series (12 + 12 +5) and connected a relay so you got 17 and 29 volts?

[future]

Hey Richard! I was watching some of your tutorial videos and loved them. I was wondering if there’s a way to get in contact with you? I saw your discord link in your bio but it says it’s no longer valid as a invite link.

[skysurfhf]

Discord link invite won't work ... Can you fix Richard? Thanks... Greatings from Portugal 🇵🇹 🌟

[dinf]

this series is getting painful to even read the titles. it is impossible to utilize atx psu to feed this type of linear stabilizer in a simple manner, and if you gonna do major, design specific restructuring of the feedback, output and control circuitry of the psu to make it even work... kinda invalidates your whole newbie friendly foolproof premise dosnt it? (not that using linear stabilizer makes much, or well, ANY sense in the first place)