Welcome
Username:

Password:


Remember me

[ ]
[ ]
Online
Guests: 35, Members: 0 ...

most ever online: 333
(Members: 3, Guests: 330) on 06 Jun : 15:15

Members: 3344
Newest member: kzoo
Members Birthdays:
No birthdays today

Next birthdays
04/28 Steve Conner (39)
04/29 GODSFUSION (30)
04/29 Zajcek (30)
Contact
If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.


Special Thanks To:
  • Aaron Holmes
  • Aaron Wheeler
  • Adam Horden
  • Alan Scrimgeour
  • Andre
  • Andrew Haynes
  • Anonymous000
  • asabase
  • Austin Weil
  • barney
  • Barry
  • Bert Hickman
  • Bill Kukowski
  • Blitzorn
  • Brandon Paradelas
  • Bruce Bowling
  • BubeeMike
  • Byong Park
  • Cesiumsponge
  • Chris F.
  • Chris Hooper
  • Corey Worthington
  • Derek Woodroffe
  • Dalus
  • Dan Strother
  • Daniel Davis
  • Daniel Uhrenholt
  • datasheetarchive
  • Dave Billington
  • Dave Marshall
  • David F.
  • Dennis Rogers
  • drelectrix
  • Dr. John Gudenas
  • Dr. Spark
  • E.TexasTesla
  • eastvoltresearch
  • Eirik Taylor
  • Erik Dyakov
  • Erlend^SE
  • Finn Hammer
  • Firebug24k
  • GalliumMan
  • Gary Peterson
  • George Slade
  • GhostNull
  • Gordon Mcknight
  • Graham Armitage
  • Grant
  • GreySoul
  • Henry H
  • IamSmooth
  • In memory of Leo Powning
  • Jacob Cash
  • James Howells
  • James Pawson
  • Jeff Greenfield
  • Jeff Thomas
  • Jesse Frost
  • Jim Mitchell
  • jlr134
  • Joe Mastroianni
  • John Forcina
  • John Oberg
  • John Willcutt
  • Jon Newcomb
  • klugesmith
  • Leslie Wright
  • Lutz Hoffman
  • Mads Barnkob
  • Martin King
  • Mats Karlsson
  • Matt Gibson
  • Matthew Guidry
  • mbd
  • Michael D'Angelo
  • Mikkel
  • mileswaldron
  • mister_rf
  • Neil Foster
  • Nick de Smith
  • Nick Soroka
  • nicklenorp
  • Nik
  • Norman Stanley
  • Patrick Coleman
  • Paul Brodie
  • Paul Jordan
  • Paul Montgomery
  • Ped
  • Peter Krogen
  • Peter Terren
  • PhilGood
  • Richard Feldman
  • Robert Bush
  • Royce Bailey
  • Scott Fusare
  • Scott Newman
  • smiffy
  • Stella
  • Steven Busic
  • Steve Conner
  • Steve Jones
  • Steve Ward
  • Sulaiman
  • Thomas Coyle
  • Thomas A. Wallace
  • Thomas W
  • Timo
  • Torch
  • Ulf Jonsson
  • vasil
  • Vaxian
  • vladi mazzilli
  • wastehl
  • Weston
  • William Kim
  • William N.
  • William Stehl
  • Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Forums
4hv.org :: Forums :: Projects
<< Previous thread | Next thread >>   

Converted Regulated ATX 5-16V 18A

Author Post
climatex
Thu Aug 11 2011, 01:06PM Print View
Registered Member #2012
Joined: Sat Mar 07 2009, 10:22AM
Location: Slovakia
Posts: 45
After a debate with Dr. Kilovolt and the other folks who assisted me with polite and informative answers to my questions ( :D ) I've succeeded in converting an ATX supply to output fully regulated output with 18 amperes on max load, everytime, doesn't matter whether at 5V or 16V. //Was lazy to replace the caps, I would crank the output to 24Vs then.//
And the overcurrent protection stayed intact. Beats all LM317s and doghouse-heatsinked linear regulators, in terms of simplicity and voltage stability under load. :)



I know this ain't much high voltage, but I thought it would be interesting enough to share with you.

There's no exact schematic for this, one has to experiment to get the proper values, however if somebody's interested I'll happily explain it for you. All you need is an appropriate potentiometer, a trimpot, some wires and desoldering work.

IIRC, I think that uzzors2k has made a tutorial on this, however I think he disabled the overvoltage and overcurrent protections, thus a short would result in an explosion :)

... And yes, the sticky black textile tape is there just for a camouflage of the hole I drilled for the meter. Wasn't fun doing that with a cordless drill. :P
Back to top
Forty
Thu Aug 11 2011, 04:59PM
Registered Member #3888
Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649
very nice work.
be careful with those currrents unless you've bundled up a bunch of the output wires together (I've melted wires before)
Back to top
Mads Barnkob
Thu Aug 11 2011, 06:15PM
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1897
climatex wrote ...

After a debate with Dr. Kilovolt and the other folks who assisted me with polite and informative answers to my questions ( :D ) I've succeeded in converting an ATX supply to output fully regulated output with 18 amperes on max load, everytime, doesn't matter whether at 5V or 16V. //Was lazy to replace the caps, I would crank the output to 24Vs then.//
And the overcurrent protection stayed intact. Beats all LM317s and doghouse-heatsinked linear regulators, in terms of simplicity and voltage stability under load. :)



I know this ain't much high voltage, but I thought it would be interesting enough to share with you.

There's no exact schematic for this, one has to experiment to get the proper values, however if somebody's interested I'll happily explain it for you. All you need is an appropriate potentiometer, a trimpot, some wires and desoldering work.

IIRC, I think that uzzors2k has made a tutorial on this, however I think he disabled the overvoltage and overcurrent protections, thus a short would result in an explosion :)

... And yes, the sticky black textile tape is there just for a camouflage of the hole I drilled for the meter. Wasn't fun doing that with a cordless drill. :P


Well since this is in the projects section I for one would like a more thorough description of the project itself, so a explanation of your work would be very welcome :)
Back to top
Website
climatex
Thu Aug 11 2011, 06:51PM
Registered Member #2012
Joined: Sat Mar 07 2009, 10:22AM
Location: Slovakia
Posts: 45
I'm glad to see interest. :)

Well, the conversion can be applied to almost any power supply up to 400 W, which is controlled with TL494, or KA7500, or any chink equivalent chip.
You have to find the first pin of the IC and disconnect it from circuit board. Next, take a 10k potentiometer (this is a good starting value) and connect the first pin directly to the second (center) terminal, or the "taper" as I call it. Then, the first terminal of your pot goes directly to +12V and the third to ground through a .. lets say, 3k3 to 5k6 resistor. This value will limit the maximum voltage, you can also put an another potentiometer (as a rheostat) in series with this resistor and ground, then you'll have both "coarse" and "fine" voltage tuning.

This alters the TL494's duty cycle. The fewer the resistance is between the ground and the first pin, and the more between the first pin and +12V, the bigger voltage is on the output. (=which is the original 12V rail, thus the maximum current load is equivalent to the original 12V output. Both 5V and 3.3V rails mustn't be loaded).

However, in most cases, the PSU won't fire up after this modification, most of them will have some voltage sensing on 5 and 12V rails. The trick is to disable overvoltage shutdown but to keep overcurrent protection intact. Usually, you can trace the 5 and 12v outputs to find two fast (or Zener) diodes, they lead to the overvoltage circuitry; desoldering both will get your PSU up and running, if you desolder just the 12V, the supply might turn off at a slight load.

When the PSU is fired up for the first time, the potentiometer must be set to be shorting the first pin with +12V and then you can safely turn it on and begin increasing voltage. If you didn't replace the original caps, which are mostly 1000M 16V chink types, you shouldn't go above 15 or 16 volts, or else the PSU might react like a hand grenade. /The same will occur when you'll short the first pin with ground, as the voltage will skyrocket up and the filtration caps are the first which will explode./

If the supply won't fire up and there are no fast/Zener diodes on the 5 and 12v rails, one might also cut a trace on the circuit board leading to the fourth pin of the TL494 IC (then you have to ground it through a 4k0 resistor, e.g.), or to pins 13,14,15. This way, the IC won't react to the PS_ON signal and neither to overvoltage nor overcurrent protection circuits, so you have to be very careful. /This was described by Uzzors2k, IIRC. I don't recommend this, though./

As you go up with voltage, it stops being nice and linear; for example here a short twitch is made, and the voltage jumps from 13V to 16.2V with ease, so if planning to go over 16V you would appreciate the "fine" tuning potentiometer I described above.

Other than that it works fine. I've just tested an 18.7A dummy load with 4.9V (voltage dropped to 4.7V on load) and the PVC insulation on the lead wiring melted through, made a disgusting smell and a short circuit. I'll upload a photo soon :P
Back to top
PSCG
Fri Aug 12 2011, 07:51AM
Registered Member #3792
Joined: Sun Mar 27 2011, 06:07PM
Location: Greece
Posts: 136
Well, the conversion can be applied to almost any power supply up to 400 W....


I've got 2 PSU's from dead computers that are 550W. I tested them and they work perfect. Can this hack work on these PSU's?
Back to top
climatex
Fri Aug 12 2011, 09:08AM
Registered Member #2012
Joined: Sat Mar 07 2009, 10:22AM
Location: Slovakia
Posts: 45
Well, I have never met with TL494-controlled PSUs that were over 400W in rating. However, if you can find the chip there, or its equivalent (DBL494, KA7500), then it should be no problem :)
Back to top

Moderators: Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Bjørn, Dave Billington, Steve Conner, Wolfram, Kizmo, Mads Barnkob

Jump:     Back to top

Powered by e107 Forum System
 
Legal Information
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.