What are the best old electrical appliances to extract electronic components from? [closed]

Question

I would like to build some simple drones and robots which I will be controlling using a microcontroller. Instead of buying expensive brand new components, I prefer to look for old electrical appliances at home or on the internet, and then extract what I need myself (small electrical motors, capacitors, resistors...)

I am really new in this field (I did some basics at university) but never did anything myself. I would like to ask the experts if they have any suggestions as to what are the best cheap appliances from which I can extract some parts easily and will cost only a few euros (or dollars)?

Answer 1

The tool you are looking for is most likey a solder iron...

That being said, why would you want to re-use old passive components for? Brand new passive components are ridiculously cheap and more environment-friendly than old ones. In addition, many components age, most notably aluminium electrolyte caps. To salvage those from old electronics would be a bad idea.

Also, old PCBs might be covered in various nasty chemicals like flame retardents and pcb lacquer. These chemicals will pollute the soldering and are hazardous to breathe when you unsolder the components. Preferably, components on such PCBs should be removed while sitting at a fume cupboard.

Why don't you go look around and see what these parts actually cost brand new, first of all? You'll find that your idea of salvaging probably makes little sense in most cases.

Answer 2

Most electronic devices have a range of components. The following are mainly those that are somewhat more special or useful.

Many parts for Robots will be easily sourced from surplus material.
Drone motors usually need high power per volume and high power per mass and often existing motors will not be adequate. Rewinding of some motors may be possible.

Printers are often a source of small electric motors. Also possibly solenoids, drive belts, mechanical and electromechanical parts & position sensors. Some have mains to low voltage power supplies fitted internally.

Dead (or alive) CFL lightbulbs provide high voltage (mains rated) transistors

LED light bulbs have AC to lower voltage DC conversion circuits but the end voltages may still be quite high.

Some but not all toasters can have timers, solenoids (to release the mechanism if power is removed).

Many consumer main powered portable device provide housings for construction and mains input to low voltage DC power supplies BUT be very careful that supplies are mains isolated on the low voltage side - many many not be.

PC/computer power supplied have high voltage transistors and capacitors and noise filter magnetics and mains rated non-polarised capacitors.

Microwave ovens have magnets, turntable motor, interlock switches and the main transformer which is useful but somewhat unusual in its magnetic design - designed to have a saggy output under load. Be aware that the magnetron MAY use fatally dangerous Beryllium ceramic insulator due to its high thermal conductivity.

Be aware that SOME older transformers and high voltage non polarised capacitors MAY use carcinogenic PCB oil for internal insulation and thermal transfer. Not so common.

Televisions contain just about everything :-) - except maybe motors.

TVs, radios and much else are good sources of surface mount components. Learn how to desolder them well. A fine tip iron is usually NOT what is needed.

Direct drive washing machines may use high power brushless DC motors useful as seriously powerful motors or for wind or water turbines.

CD & DVD players contain motors which MAY be able to be rewound to have far greater power than originally.

Many more ...

Answer 3

In the days when electronics hobbyists build radios using 5 transistors and a linear power supply using 10 transistors (a fancy one :-) ) then indeed it would be possible to re-use some components found in discarded radios and televisions.

But fast forward to the 21st century and a lot has changed. Most consumer products use a few ICs which are often proprietary and only suitable for that application. In a TV you'll find a TV-chip. There will be some discrete components but this will often be SMD components, not handy for a beginner. And only of you can identify the component. And I can buy 20 brand new ones on Ebay for $1 and then I know the type so I can look at the datasheet.

You want to build (simple) drones and robots. Do you have any idea what the complexity is needed to make a drown fly, OK not much but you might want to be able to remotely control it ? Then you need a radio chip and not the one that is in a TV. They both might contain 10,000 transistors (just a guess) the TV chip and a drone's radio chip I mean. My point is that the complexity of drones etc is such that you will not find much useful components in everyday electronics.

Also, components and kits to build something yourself is now so cheap that there is little point in trying to re-use discarded components. I often use an Arduino clone from Ebay for my projects, these cost less than $ 2 each. Sure there are microcontrollers in consumer devices as well but for me these are not as easy to use as an Arduino.

Answer 4

When I was a kid, I used to disassemble the old electronic devices my parents were getting rid of so I could build circuits that I found in electronics magazines. One of the best sources for components was old VCRs. They have great motors in them, and a wide variety of resistors, capacitors, and transistors. You just need a decent soldering iron, a steady hand, and possibly a desoldering tool.

Answer 5

A lot of appliances have reusable 8051-type microcontrollers - they are ubiquitous in monitors, TVs, white goods, car electronics, early harddrives and CDROM drives... and if you combine them with an external program memory (28F... series flash chips or 27C... series EPROMs are often suitable, and can be found in a lot of older computer scrap) and a means to write to it (specialized kit - build it or ebay it), they are an old-school but fun MCU platform. Almost all of the 40/68/84-Pin versions can be wired up in a way to use an external program memory, even if they are ROM or OTP devices.

Optical mice very often have an 68HCxx based reprogrammable MCU in them.

Also, always look for professional-grade, military, industrial control, or test equipment - these tend to use valuable, well documented generic ICs rather than application-specific parts.

Also, text-only, one to four line, monochrome alphanumeric LCD displays found in all kinds of equipment are often of the well-documented HD44780-like type. Forget about any LCD displays that work with custom segments (not very useful and difficult to drive), except such that are made to work with a voltmeter chip like ICL7106 usually found in the same equipment.

Answer 6

When I was in junior high (often called middle school now), I got a hold of a pinball machine that had been seized at a local men's club because members were using it for gambling. Now most kids would want to keep the machine as is in their bedroom and play all day, like today's video games. Not me, I was more interested in the innards.

So I tore it all down and the parts inside (all electromechanical, this was 55+ years ago -- relays, switches, motors, etc.) provided me a wealth of parts that I used for projects for many years thereafter.

The technology has obviously changed a lot since then, but I would assume a newer pinball machine (I mean a real one, with flippers and lights etc, not a CRT or LCD) would still have lots of interesting electromechanical stuff inside, especially for robotics, along with a PCB with a microcontroller that may or may not be usable, but it would at least have some driver circuitry.