Hacking Power Supply

I am taking the plunge and building a Work Bench Power Supply from a PC Desktop power supply.

The guy in the video suggest that a approximate 0.5 amp load be put on the 5 volt rail (12 volt rail on newer) of the switching PS in order to stabilize it.

This diagram shows how he suggests putting it together.

What say you?

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Former Member over 13 years ago in reply to billabott +2

Of the dozens of PC ATX-type power supplies I've used in analog, digital, and electrochemical circuits, I've never needed to add a "stabilizing" resistor. Basically, ground out the green wire, and the…
R_Phoenix over 13 years ago +2

The resistor isn't to stabilize the PSU, but rather give the system a dummy load on the 5v that helps "pull up" the 12. Taking the green wire to ground will still turn it on, but then messure the voltage…
terryking over 13 years ago in reply to R_Phoenix +1

Power resistors are hard to find. Just use a 12V Automotive tail light / side light bulb on the 5V supply. It will be bright enough to function as a "Pilot light" and will last almost forever at 5V...…

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R_Phoenix over 13 years ago

The resistor isn't to stabilize the PSU, but rather give the system a dummy load on the 5v that helps "pull up" the 12.
Taking the green wire to ground will still turn it on, but then messure the voltage with a meter. It will most likly be under 12 volts, something like 11.7 volts instead. Also you will notice that about an amp of draw on the 12 volt will trigger the crowbar and shut it down with no load on the 5v rail.

The resistor isn't "needed", but it is suggested.

Here's mine,
http://www.jassper.com/other/project.pdf
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terryking over 13 years ago in reply to R_Phoenix

Power resistors are hard to find. Just use a 12V Automotive tail light / side light bulb on the 5V supply.

It will be bright enough to function as a "Pilot light" and will last almost forever at 5V...

...works on every AT / ATX supply I've used....
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terryking over 13 years ago in reply to R_Phoenix

Power resistors are hard to find. Just use a 12V Automotive tail light / side light bulb on the 5V supply.

It will be bright enough to function as a "Pilot light" and will last almost forever at 5V...

...works on every AT / ATX supply I've used....
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Anonymous-58970 over 13 years ago in reply to terryking

12v automotive tail light iv never thought of that terry king il do that to my project and give it old tube circuits feel as well
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billabott over 13 years ago in reply to Anonymous-58970

Q: What is the normal range (or average) for current draw on a vacuum tube heater element.
I am trying to determine if there is a potential of using the VTs in lieu of power resistors.

A: Wikipedia states that tubes like 12BA6, 12BE6 are 12.6 volts.

Here is a fun Vacuum Tube site that indicates the heater of 12B4A draws 12.6/6.3 V, 0.3/0.6 A.

Conclusion: I would need 2 vacuum tubes and sockets to put the approx. 0.6 amp load on the 12 volt rail of my "Steam Punk" power supply.
( I have plenty of tubes; so I will have to find some new/nos sockets for them.)
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