Part Sources
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Where to Get Old Equipment
Garage Sales
Garage sales sometimes contain treasure but your typical sale is mostly baby clothes and crockery. Garage sales can also be overpriced because of sentiment. Yes, maybe you spent a four-figure sum on your 386, but it's time to let go.
To do real garage sale shopping, wait for the right season and visit a whole batch.
School Fairs
These are great for real bargains on old appliances. Most junk has been donated free and the sellers have no sentimental attachment.
Old cameras and TVs galore, as well as computers sometimes.
Ham fests
Hamfests (Amateur Radio conventions) have both commercial vendors and "tailgaters" (individuals selling personal items) who sell all kinds of electrical and electronic parts, as well as radio transmitters, receivers, transceivers and accessories for use in the Amateur Radio bands, test equipment (oscilloscopes, multimeters, component testers, signal generators, frequency counters, spectrum analyzers), computers and computer parts from almost every generation, and the occasional consumer electronics from recent stereo receivers to antique broadcast-band radios. Prices are quite reasonable (except of course for collectible items), and towards the end of the day, as tailgating sellers start packing up to leave, prices often drop, sometimes to free. Most hamfests in the USA are listed in this database:
http://www.arrl.org/hamfests.html
There are also some informal yearly "swapfests" not listed in the database. When at a hamfest, look for flyers advertising upcoming hamfests and swapfests.
Repair Shops
Repair shops generally don't do much repairing. Instead, repairers just narrow down the fault to one area, rip that out and replace. This means many repair shops have lots of junk wasting space that needs to be taken to the tip and are repairers are often very grateful to anyone who'll save them the hassle.
Avoid asking for stuff at a repair shop when customers are in store. Some customers take offence at the idea of their junk being useful to others and shop owners are wary of that.
For similar reasons, most owners won't give you anything if they suspect you might try to fix it. While they don't care if some electronics geek spends a week trying to fix the irreparable, customers will complain about the shop giving away things that "could" be repaired. Some people offer to smash up any casings instore to prove that there is no intent to repair.
Dumpster Diving
Tip Shops
Many appliances in tip shops just have dented/cracked cases.
Sometimes delicate things like specialist glassware can be found without even a scratch.
Is this "tip shop" the same thing as what people in the U.S. call a "pawn shop" ?
Shops
Cigar shops throw out many boxes used to hold cigars. If you ask for some empty boxes they will most likely give you some. The boxes come in many diffrent shapes, sizes and colors. They can be used to store parts, contain projects or used as a controller for projects you don't want to be near by during operation.
General Waste Collection Days
In countries such as Australia, around 3 times a year, waste is thrown out into a pile by the kerb awaiting collection. Free for the taking, if you don't mind the embarrassment of the stares of passerbyers.
Recycling Centres / The Tip
In the UK at least, you can go to most recycling centres and browse the racks of electrical gear. It's best to go mid week if possible, and always ask permission before you dive in. Expect to pay about $10 per appliance (monitor, tv, or whole computer). When you have removed the parts you require, simply take it back!
Car Scrap Yards
A great source of ignition coils, and abandoned appliances like old TVs (you often see scrapped cars containing old appliances). Has the added bonus that you can dismantle while you are there.
What's Inside
TVs and Monitors
TVs and monitors are the best source for the legendary flyback transformer. Try to look for the older TVs, which usually contain an AC flyback with external rectification, as opposed to the DC flybacks of new TVs, in which the diodes are potted internally and almost impossible to bypass.
TVs and monitors are also a rich source for semiconductors. The main board usually contains at least 1 PWM chip, an audio amplifier and optocouplers. Also look out for voltage regulators such as the 78xx series and LM317's. Most also contain MOSFETs, either of the 2SKxxx series, or the IRFxxx series, the most commmon being the IRF630. Keep a look out for comparators and op-amps as well.
- Degauss coils are a great source for winding wire. Wire sizes range from approx 22-30Ga.
- You may carefully remove the screen from inside the CRT, which acts as a nice sieve.
- After removing the screen(mesh), the flourecent coating can be washed off of the glass and saved.
- Rich source of capacitors and resistors.
- Several switch mode transformer cores! These can be used as is, or rewound by pulling off the tape and very carefully cutting the glue joints. (some prefer to boil the cores.)
- HEAT SINKS
The high voltage filter capacitors, mains filters and heatsinks are also useful in other projects.
Microwaves
One of the greatests finds you can achieve. Fortunately, they are everywhere. Generally, you will get:
- Timer circuit
- 2 heavy 120V relays
- 1 Vacuum florescent display
- 1 approx 2000V 750-1750W tranformer (can easily be rewound to any voltage, dubbed MOT)
- 1 0.6-1.0uF, 1700-2400V nonpolar capacitor (dubbed MOC)
- 1 6000V 200-500mA HV diode
- 1 6 RPM Motor
- 1 possibly some high temp or high voltage wire
- 1 2.4Ghz Magnetron, (or some brass mesh and two really powerful magnets, whichever way you see it)
- Often, plexiglass or tempered glass from front)
- 1 120V fan; can be used as is, rewound as a transformer, or scavenged for it's 27-30Ga windings.
- Rubber feet, Heavy duty cord and fuse holder, 120V light, 2-3 thermal fuses
- I always cut out the vents and use them to align drill holes for homemade grills.
- If you obtain a newer IGBT version, you should get 2 or 4 IGBTs, minus some of the parts above.
Cameras and Accessories
The flash circuit can be extracted easily from most cameras and will contain a nice 330 V 220-600 µF capacitor, along with a powerful charging circuit. The charging circuits from the non-disposable cameras are admittedly quite hard to figure out, but in the case of disposable cameras, its just a case of applying a voltage to the battery connector.
Disposable cameras, which can be had free at photo processing stores, are an excellent source of 330 V 70-160 µF pulse discharge capacitors (often refered to as Photoflash Capacitor or PFC). These are great for a coil gun, as they lower internal resistance leads to considerable peak currents when discharged.
The xenon flash tube could also be used as a lower power triggered spark gap for CG switching, or to study the plasma effects created when a high voltage is applied between the two ends
Disposable cameras without flashes aren't very useful. They have some cheap plastic optics inside but that's about it.
Professional flash units are often inexpensive and in working order (professionals don't use dented flash units, thankyou). They have the same sort of parts as the flash unit from a disposable camera but better. Bigger tube, bigger capacitor and bigger inverter.
VCRs
VCRs contain a nice mains transformer which should be capable of 2A at several voltages. Also contains a nice motor used for spinning the tape.
Pulleys, tires, audio/video jacks, VFDs, IR consoles, etc.
The modulator, if removed carefully, can easily be pitted with a 7805 to produce a stand alone RF modulator. (RCA to CH3/4)
The "rotating transformer" in the spinning tape head might be useful for a propeller clock. The head is a very nice source of bearings (usually 2), if you are willing to take out all the screws.
Computers and Computer Stuff
Most computer components are quite speciallised, and contain no useful parts to an experimenter. Do not destroy a perfectly good PCI card unless you are sure you cannot sell it for a decent price. The PSU, CD drives, old floppy drives (5.25") and HDDs usually contain the most useful parts in a computer.
Hard Disks
Computer hard disk drives (HDDs) usually contain excellent NIB magnets. Very old ones sometimes have stepper motors instead but these are very nice too and shouldn't be a disappointment. HDDs also contain motors for spinning the platters. The platters themselves look like they ought to be useful but probably aren't. They can however can be used as projectiles in Thompson launchers.
Many places are reluctant to sell or give away used HDDs directly because of the privacy uproar this could cause. They do, however, usually come with any old computer.
Putting 2 platters next to each other is an interested experience. They "stick" together, almost impossible to pull directly apart. But you can slide them apart easily.
CD ROM Drives
CDs do not yeild as many useful components, unless of course you are into desoldering SM stuff. The older <24x speed ones have a DC motor to spin up the cd drive, which newer ones use a stepper motor. The DC motors can be "overvolted" (personally, i have applied 20V to a 12V one with no problems)and will spin a CD up to a considerable speed.
The laser diode use to read the disc could also be salvaged. The main board occassionally contains a thru-hole voltage regulator, usually of the 78xx series.
Look out for the old CD players with a "play" button on the front, as these can be converted into a CD player by simply applying power, inserting an audio CD and pressing play.
PC PSUs
PC PSUs are full of useful components. Almost all PSUs, use a TL494 chip- a very useful PWM chip with independant frequency and duty cycle adjustment, and is bound to find uses in projects where a constant frequency is required. Computer PSUs also contain a half bridge which sends current into the ferrite transformer. Usually the MOSFETs used in older PSUs are 2SK2038's. In the secondary rectification section, there are 2 high current diodes and a schotty diode, usually around 40V, 10A. Filter capacitors and a powdered iron toriod as also present.
Printers
- STEPPER MOTORS! Often two, and one DC motor, but sometimes you'll get 3 steppers.
- Very nice polished rods.
- Optosensors
- 30V several-amp PSU
- USB jacks
Laser Models Often Include:
- 1 Laser head/lens assy/PSU; invisible, not very powerful.
- 1 BIG stepper motor
- 1 very long magnetic rod (if you're willing to get messy)
- 1 heating element
- Older models include a VFD or LCD dot display
- 1 big PSU
- Fusor element
- Metal gear trains (in the LaserJet4&6)
Tape/CD Players, etc
Where to Find a Part
A B C
- Capacitors- PSUs in TVs, monitors,computers, etc. Microwaves contain a 2200 VAC 1 µF capacitor which fares alright in pulse discharge. Washing machines sometimes contain a motor starting capacitor
D E F
- Ferrite cores- monitors, TVs, SMPS
- Flybacks- TVs, monitors, projectors, laserprinters/copiers
G H
- Heatsinks- PSUs in TVs, monitors, and computers. Amplifiers, UPS supplies.
I
- IGBTs- Inverter microwaves, big SMPS power supplies.
J K L
- Laser Diodes- DVD burners(red), CD Burners(some red, mostly invisible), Laser printers
M
- Magnets- Inside the magnetron from a microwave, hard disks
- MOSFETs- SMPS power supplies from computers, monitors, TVs, etc
N O P Q R S T
- Transformer (iron)- Almost everything which goes into the mains.
U V W X Y Z
