From Open Circuits
Salvage Ideas You may not have thought of. Repurposing Junk
Of course you can use the components in a way consistent with their original use, but :
Use upside down, solder components to the headers, that is the bottom of the header that was soldered to the board is soldered to the component. Then insert the component into a prototyping solderless board. The component makes a much better, easier connection than just using the component leads.
 Hard Drive Cables
Use any time you need many many connections and would like to be able to unplug the connection. Additionally you sometime find components like LCD displays that will plug into cable. I usually cut the cable and use only one of its plugs, soldering the connections on the other end. You can also reduce the width of the cable and/or plug ( although the plug will be weaker and may need reinforcement ).
Some plugs are designed to come out at right angles, giving them very long pins. With a little work you can bend these to insert into a protoboard ( along the center line so pins are not shorted together ). I russ_hensel will post a picture when I gettoit.
 Keyboard Cables and Plugs
I get quite a few Keyboard Cables and Plugs, but until recently did not know what to do with them. Then I had a flash – I build a lot of things, but do not really want to deal with a power supply. Why not have one central power supply and plug in each project. I took 3 dual keyboard ( and mouse ) plugs and wired them in series. The supply ( again from a computer ) provides +5 volts and + and – 12 volts. This is good power for most of what I do. The cables are soldered into the project and plug in when I need power. The only limit is that I would keep the power to a few hundred ma.
 Computer Power Supplies as Bench Top Power
Lots of projects published on this, here are a few:
- Converting a computer ATX power supply to a really useful lab power supply
- Jump Start A PSU
- Convert an ATX Power Supply Into a Regular DC Power Supply!
- My Suped Up PowerSupply!
 other modifications of ATX computer power supplies
- Converting ATX power supply to run off a 24 VDC or 12 VDC battery power
 Those Odd Motors
CD Roms, VCRs..... Using these a motors is hard because they normally use complex drive arrangements. Think outside the box: you may be able to:
- Use as a rotery encoder ( google it, there are links out there )
- Nice bearings use as an anemometer bearing for example.
- Rip it up for the magnets
- Find the hall effect sensor and use it.
- Think some have figured out how to uses as generators for POV displays like propeller clocks.
 Dead Mice
Many have the same cable as keyboards ( see elsware on this page ). The ones with balls also have 2 optical rotery encoders. When you get a hundred or more balls there must be something clever to do with them. Wheel mice have an extra rotary encoder arrangement. Some have pretty nice switches.
Optical mice have a tiny camera on a chip. This has been used as a low-res scanner (google). Other uses may come up. There is also a beefy red led.
USB mice especially may have the cable socketed. In any case you'll end up with a cable you can use to USB-power a device. The controller needs a clock source so there's a resonator and often also a 3V regulator.