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PC PSU into a Lab PSU

bennett326

bennett326

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wa prettier than mine on the inside good job

:edit ill post pics in abit
 
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bennett326

bennett326

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IMAG0135.jpg


IMAG0133.jpg


[IMG}http://i1215.photobucket.com/albums/cc517/bennett326/IMAG0134.jpg[/IMG]

dont laugh at where the electrical tape is i put a hole there i decided i didnt want anymore :p
 
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LaZeRz

LaZeRz

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Haha, nice work!

Btw, the wire your using is pretty thin, you might need some 16 gauge or so. Even with 5 strands of 26 gauge im still getting significant voltage drops at around 5 amps.

Oh yeh, why are there 4 pots? Im guessing course and fine adjustment?
 
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bennett326

bennett326

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LaZeRz said:
Haha, nice work!

Btw, the wire your using is pretty thin, you might need some 16 gauge or so. Even with 5 strands of 26 gauge im still getting significant voltage drops at around 5 amps.

Oh yeh, why are there 4 pots? Im guessing course and fine adjustment?
Click to expand...

coarse and fine for both current and voltage

and i haven't drawn near that much for anything but i may buy some thicker wire.

also the silicone wire can handle 5 amps so you shouldn't need more than a couple strands :thinking:
 
Cyparagon

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5 amps before it melts, maybe. Up to that point, you're generating increasing amounts of heat. The heat comes from voltage drop across the wire. The smaller the wire, the larger the voltage drop. You want to minimize voltage drop because not only does it produce unwanted heat, it also as the name suggests, drops voltage. You may get 5V at the end terminals under no load, but under heavy load, that might sag to 4.5V or lower. This defeats the purpose of using a voltage regulator.

The insulation (PVC/rubber/silicone) has little (if anything) to do with the current capacity of the wire. It's the cross-sectional area of the copper you want to look at. It's 26AWG, isn't it? If you plan to send 5A through it, you need a minimum of 22AWG. Bigger is better. Use this as a guide.
 
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bennett326

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alright ill get some bigger wire i was mainly saying im not really using 5amps much so..
 
LaZeRz

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Cyparagon said:
5 amps before it melts, maybe. Up to that point, you're generating increasing amounts of heat. The heat comes from voltage drop across the wire. The smaller the wire, the larger the voltage drop. You want to minimize voltage drop because not only does it produce unwanted heat, it also as the name suggests, drops voltage. You may get 5V at the end terminals under no load, but under heavy load, that might sag to 4.5V or lower. This defeats the purpose of using a voltage regulator.

The insulation (PVC/rubber/silicone) has little (if anything) to do with the current capacity of the wire. It's the cross-sectional area of the copper you want to look at. It's 26AWG, isn't it? If you plan to send 5A through it, you need a minimum of 22AWG. Bigger is better. Use this as a guide.
Click to expand...

Indeed. Im experiencing voltage drops (0.5v) with 5 strands of 26 gauge wire. I'm planning on changing it over to 14/16 gauge.'

EDIT: Bennett, may I ask what regulators you used for your CC and CV?
 
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bennett326

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LaZeRz said:
Indeed. Im experiencing voltage drops (0.5v) with 5 strands of 26 gauge wire. I'm planning on changing it over to 14/16 gauge.'

EDIT: Bennett, may I ask what regulators you used for your CC and CV?
Click to expand...

just lm338s :undecided: that was before i knew much at all about PSUs. or even electronics :p

im looking into making a similar version to daves from EEV blog its very cool, lots of info. be warned long videos:tinfoil:Daves blog here
 
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Wolfman29

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So I recently did this for a nice, 12V, 15A PSU for my high-voltage experimenting.... In my PSU, I basically just grabbed two of the 12V leads and shoved those to a banana plug port. Think those two 12V will be able to handle 15A+? They are pretty hefty, but stranded: much thinker than my 22 gauge wire... I think something like... I dunno, 18 gauge?
 
LaZeRz

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If you grabbed all of the 4-5 yellow wires than it should handle the current finely :)

I've still got 2 more PSU's that im going to convert :D
 
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Wolfman29

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I only grabbed two of 'em :\ The rest would have cluttered it up far too much... think it should be able to handle it?
 
bennett326

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Wolfman29 said:
I only grabbed two of 'em :\ The rest would have cluttered it up far too much... think it should be able to handle it?
Click to expand...

probably not sorry man:eek:. i did the same thing on one of my PSUs i could only get a amp, with all of them i can get 5 amps :)
 
LaZeRz

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Even if you can pull 15 amps from it before it melts, the wires will end up dropping huge amounts of voltage :p
 
Wolfman29

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Hmm. Maybe I will open it up and see if I can hook up the rest of the wires. I'm looking to making this a proto-power source for a step-up and then step-down 0-50V 0-10A PSU... :p
 
LaZeRz

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That would be pretty cool! :)

Im planning on adding an adjustable current option to my PSU but I'm going to have to find some massive pots, lol

My PSU isn't very efficient at charging my boostcap since its constantly dropping around 9 volts (boostcap@2.7v) So im going to grab another LD1084 and hook it up to the 5volt line on my 2nd PSU. I'm probably also going to grab an IC capable of 10-15amps to make it more useful :D
 
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