power supply software switch hack

Posted on 2003-02-23
Medium Priority
Last Modified: 2010-04-26
Anyone know the proper way to hack a software power supply switch for use as a hard switch?  I am using the supply for electronic uses outside of a computer.  

Taking what seems to be the software switch - only connection with constant +5V - and grounding the white wire thorugh a 300ohm resistor (logic low) seems to turn the supply on.  Should I use a bigger or smaller resistor?  Is this the proper way to do this?  Any suggestions or improvements?
Question by:dhammy69
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 32

Accepted Solution

jhance earned 150 total points
ID: 8004715
The use of a 300 Ohm resistor seems reasonable.  You could, of course, use a smaller value since a "real" pushbutton switch on the PC front-panel shorts the "PO" signal to "GROUND" to signal a POWERON.

If you need to control this from a different piece of equipment, however, I'd recommend ISOLATION to prevent and ground differential or noise problems between the two units.  The best way to to this is via a RELAY or an OPTO-ISOLATOR device.  If you need more details about either of these, please let me know and I can draw some schematics for you.
LVL 12

Expert Comment

ID: 8005091
The supply is intended to be switched with a logic gate. No resistor is needed.. You can also use a transistor, optocoupler, mechanical relay, or any other similar device.
You can also permanently groung the pin, and only use the main ac switch in the back.

Author Comment

ID: 8005468
I guess I was worried about pulling too much current by switching the white 'signal' straight to ground.  But I guess that is how it is designed to be used.  I will add a straight toggle switch (no resistor) and I'll be done - no need for isolating in this case.  Thanks!

Featured Post


Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Windows 7 does not have the best desktop search built in. This is something Windows 7 users have struggled with. You type something in, and your search results don’t always match what you are looking for, or it doesn’t actually work at all. There ar…
There are many software programs on offer that will claim to magically speed up your computer. The best advice I can give you is to avoid them like the plague, because they will often cause far more problems than they solve. Try some of these "do it…
Finding and deleting duplicate (picture) files can be a time consuming task. My wife and I, our three kids and their families all share one dilemma: Managing our pictures. Between desktops, laptops, phones, tablets, and cameras; over the last decade…
Add bar graphs to Access queries using Unicode block characters. Graphs appear on every record in the color you want. Give life to numbers. Hopes this gives you ideas on visualizing your data in new ways ~ Create a calculated field in a query: …
Suggested Courses

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question