Electronic parts from...

PC monitor | VCR | CD-ROM | FDD| HDD
Laptop | Motherboard | SmartCard reader| Printer

Hello!
I could get hold of some PC monitors, either broken or not. Since some electronic parts can be hard to find in shops nowadays (toroids, transformers, power resistors, ...), I always unsolder useful components from any electronic device whose destination is the trash can.
Let's see what a bulk 15 inches PC monitor can provide... Furher electronic devices were dismantled afterwards, so they were added here.

• Ferrite Beads. These almost-impossible-to-buy ferrite cylinders are very useful if you want to filter out R.F. on a conductor. As example, take the need for filtering the DC line powering a local oscillator for a receiver/transmitter: you don't want that signal to walk around your whole circuit through the +Vcc line, do you?!
• Toroidal Cores. I found two on a monitor. I assume these had the same purpose of the ferrite beads, but on the main 220V AC power cord. They might be no good for RF/HF applications!
• Power Resistors. Altough I doubt they might work at high frequencies (above 1-2 MHz), you can use them to build a discharger for your NiCd rechargeable batteries. Some measurements have shown that these "inductive" resistors might be used in the HF range for QRP applications.
• High Voltage Capacitors. They are not the silver-mica ones, but might serve in some power applications, such as a loud audio amplifier, or some 137 kHz transmitter.
• Inductors and Transformers. A monitor has a built-in switching power supply. It requires transformers and high-voltage capacitors. Unfortunately I wasn't able to find any information on my transformers and inductors...
• Heat sinks. A monitor has 4 or more power transistors, which need to dissipate heat. You can certainly get some heat sinks of various sizes.
• Oscillator or XTAL. Video signals are synchronous, so there must be some sort of signal generator inside the monitor. I found a 3.58 MHz ceramic resonator and a 14.318 MHz XTAL.
• Voltage Stabilizers. Diodes for AC to DC rectification and a 12Vdc stabilizer (7812) were unsoldered.
• Transistors. There are plenty in a TV but... I cound't find any meaning of the code printed on their case :-( If you have a clue, just take them! :-)
• Cable! How could I forget this? Yes, the VGA cable that connects the video-card to the monitor. It carries some 10 wires, and you can reuse it for another application: you already have a robust connector and 1.5 metre cable!
• Knobs. Older screens had analog control of luminosity, contrast, ..., so they carried some nice knobs (I got 7 identical in a row!)
• Rubber feet. Used with an anti-skid purpose, I could finally glue 4 rubber feet under my CW key, so it wouldn't slide all around.

Here is part 2 of this sequel :-)
A VCR is another video-related device, so you shouldn't expect to find many different components, if compared with a monitor.

• XTAL. The standard PAL frequency is 4.433619 MHz. I found two XTALs in my Mitsubishi VCR (BTW, very clean assembly guys!)
• XTAL, 2. I am not sure these are XTALs, since I never managed to get them oscillate. Their shape is cylindric, two pins, metallic case. Their label doesn't make much sense to me (AE63, P23501Z). Any idea?
• Ceramic Filter. You find them only if the VCR has a TV modulator/output. I found two 5.5 MHz filters. I still have to find out their bandwidth...
• TV module. You can opt for unsoldering the whole RF module of VCR's receiver. I have seen a project for a 6m preamp, but other uses might come up.
• Photocoupler. It was in the DC power supply of my VCR. Don't ask me what it did there, but it's useful anyway.
• IR diodes and phototransistors. Apparently my Mitsubishi used many infrader-diode/phototransistor couples to sense the presence of the cassette, maybe the tape state, ... I have no use of them, so didn't touch them.
• Others... See what is written above for the monitor concerning the switching power supply: condensers, transformers, ferrite beads (no toroids in the VCR :-( ).
• Remote control. The first thought is to throw it away. But it might become useful! Most VCR remotes allow TV control as well (at least power, channel up/down and volume), and are programmable to work with most TV sets! (my Mitsubishi was; JVC isn't :-( ). Don't forget to keep the VCR manual that refers to remote programming for future reference!

Disassembling a CD-ROM drive is a thrilling experience. I had 4, all with a different problem, all non-working, all pretty old (max was 4x).

• XTAL. Strange frequencies, some players even had more than one. XTALs are the few components in CD drives that are not SMD.
• DC motors. There are at least 3: tray, CD rotation, head shift. They operate at 5 or 12V DC. Very high speed.
• (IR) laser, especially disk writers have a powerful laser head. But CAREFUL, because only DVD drives have visible (red) laser heads, CD are infrared, so invisible but HARMFUL for eyes!

Why someone would ever want to disassemble a laptop?! That's right. I first tried to repair it :-) It's always a valuable piece of hardware afterall!

• Battery. Usually the battery is the first thing to die in a laptop. I was lucky enough to get hold of 2 old and working batteries. Altought voltages may vary, current capacity (beyond 1500 mAH) is enough to power a HT RTX for a while.
• Hard Disk. You never know, might be used/resold as a spare part, as well as the
• Floppy drive, whose technology hasn't evolved too much: you might even use it on a modern laptop! Of course you can't really be sure they work...
• Oscilators. Looks to me that older laptops grew oscillators inside them :-) An old 386 IBM had 10 of them, all at a different frequency. One is 28.322 MHz! WOW! A all-in-one CW TX for 10m, add a filter and you're on the air! If you don't know what I'm talking about, these are 4-pin packages that take 5V (note: it might work with 3.3V or even less! see my 10m QRPp TX project) and return a square wave at the stamped frequency.
• Toroids & Ferrite Beads: see above for some ideas.

Computer motherboards are starting to be cheap and readily available. Not much can be scrounged from them, mainly digital components, and you certainly need a good method to desolder SMD components (or solder points on both sides of the PCB)

• To Be Completed...

A Smard Card Reader is not a common device you might find in the trash can down the corner, and offers few useful parts:

• Serial/USB cable, with the proper connector on one side. Serial readers take their power supply from PS/2 ports, so their cable has two connectors
• Serial driver chip, that converts TTL digital levels to RS-232 (for serial readers only), like MAX232 or ADM202
• Step-Up DC-DC Converter; my sample had a MAX856 inside (3.3 or 5V output)
• I also found a PIC16C microcontroller
• LED
• A smart card reader hardware, obviously
• a xtal

Printers nowadays are very cheap and probably mechanically weak. Very few things are useful:

• Power supply, that also has a 24V or so output for driving a RF power amplifier
• DC motors
• Assorted parts: LED(s), cables, oscillator/XTAL

Eccetto dove diversamente specificato, i contenuti di questo sito sono rilasciati sotto Licenza Creative Commons.
The material on this page is licensed under a Creative Commons License, unless otherwise noted.