old computer & stereo electronics useful for making md stuff?

[sean from ma]

I've got a couple early 1990s pentium 200 computers, a broken boom-box, and an old garage door setup (remote, motor, wall pad).

Are there any or enough electronic components in these to build a detector?
I'm trying to decide if I should chuck all this stuff in the trash, or save it for electronic parts that might be useful for making something metal detector related.

I know it'd be easier and more reliable to buy new components. I'm just interested in making something useful from this junk (actually, I already used the boombox's ferrite antenna to replace the coil on a cheapo toy detector & turn it into a probe).

The Hammerhead project has caught my eye as a good winter project, and perhaps a relatively inexpensive means to a second detector that'd work at saltwater beaches. However, I don't know much about electronics, though I'm handy and able to figure stuff out.

What's the ballpark cost (total) for the parts to make a Hammerhead?
Thanks.

[bbsailor]

Re: old computer & stereo electronics useful for making md stuff?

Sean,

Salvage the Computer Power Supply to make a good bench supply with +/- 5V and 12 V. It is good enough to power some metal detector prototypes on the bench.

Just get a good desoldering vacuum tool to disassemble circuit components. Then find some small plastic drawer cabnets to organize these parts.

Other than the circuit board, MOSFET coil driver and some logic and specialized power supply ICs/chips, you should find these recycled parts to be the start of a handy scrap box. It is more useful when it is organized. You should be able to build the Hammerhead circuit board for less than $50 and then another $25 to finish it up in a housing with the necessary shaft parts. The more resourceful you are in using and substuting alternate parts will help you keep the costs down to the costs I have suggested.

Hays Electronics has a good variety of coil housings much cheaper than you can make one yourself. You can get some coil wire from an old TV or computer monitor yoke.

A scope is necessary to monitor your progress and better understand the circuits as they evolve. A signal generator up to 2MHZ with a frequency counter and scope are good to test the self resonance of PI coils.

An LCR meter is handy but not necessary as long as you have the above.

One good place to start is to order the circuit board for the Hammerhead PI from Carl. Then you will see the physical size parts that must fit on the circuit board.


bbsailor

[sean from ma]

Re: old computer & stereo electronics useful for making md stuff?

Thanks for the reply and information.
Do you have any good links for websites with introductory electronics info, like reading diagrams etc.?

[bbsailor]

Re: old computer & stereo electronics useful for making md stuff?

Do a web search on the words "electronic kits" and purchase something simple like a simple headphone/small speaker audio amplifier (less than $7.00) (one watt or less) that you can use later.

Learn to identify various electronic components, know which ones need to be installed in a particular direction (polarity sensitive) and how to read the values stamped on the body of the component.

Key components are: resistors, capacitors (various types), diodes, ICs, pots, trimmers, batteries, jacks, plugs and various board connection options. Stop by your local Radio Shack and look for a book on introductory electronics and build the audio kit mentioned above. The Shack may even have some. Once it works, go on to a kit a little more complicated with some digital integrated circuits(ICs).

Get a small soldering iron 15/30 watt dual heat, solder and practice soldering on junk parts first. Taking old things apart is a good way to get you feet wet. Big connections require more heat using a 100 watt gun.

Reading a schematic may look like some cryptic language at first, but all it does is show you the physical connections between the various components mentioned above.

This is a skill you can use well into the future so take your time, ask questions and learn by doing.

bbsailor