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From UpCycleIt

In electronics, printed circuit boards, or PCBs, are used to mechanically support and electrically connect electronic components using conductive pathways, or traces, etched from copper sheets laminated onto a non-conductive substrate. Alternative names are printed wiring board (PWB),and etched wiring board. Populating the board with electronic components forms a printed circuit assembly (PCA), also known as a printed circuit board assembly (PCBA). While this article does not specify how to upcycle a PCB, it provides information on how to get all that you can out of a printed circuit board if it has reached the end of it's service life.

[edit] WARNING

Many electronics and PCBs contain large capacitors that could seriously injure and/or kill you. A television set is one such example. Do Not attempt anything you have read in this article unless you are absolutely positive that all capacitors are discharged. If you do not know how to properly discharge a capacitor, Do Not attempt anything in this article. This has some information on discharging a capacitor. If you do not feel fully confident with your knowledge of what you are doing, then please Do Not attempt anything in this article. We will not be held liable for any injuries resulting from the use of the information in this article. Please consult our UpCycleIt:General disclaimer page for further information.

[edit] Electronic Components

PCBs are populated with hundreds and sometimes thousands of tiny electronic compenents, each having its own special purpose. Most of these components still work even if the device is broken. Instead of throwing the whole PCB away you should first try to get as many of the components off of the PCB as possible. For more info on how to actually get electronics components off a PCB, refer to the desoldering guide

[edit] Resistors

A resistor is a two-terminal electrical or electronic component that resists an electric current by producing a voltage drop between its terminals in accordance with Ohm's law. These are extremely useful and are used in almost every electronics project.

[edit] Axial-lead

Axial-lead resistors

These are among the more common types of resistors used in projects due mostly to their inherent ease of use. Most axial resistors use a pattern of colored stripes to indicate resistance. Refer to the chart to accurately read the resistance.

[edit] SMT

The four black components are the SMT resistors

Surface mounted resistors are printed with numerical values in a code related to that used on axial resistors. Standard-tolerance Surface Mount Technology (SMT) resistors are marked with a three-digit code, in which the first two digits are the first two significant digits of the value and the third digit is the power of ten (the number of zeroes). SMT components are typically of less use to the average DIY-er since they require much more skill to desolder/solder. It's typically easier to simply use axial-lead resistors.

[edit] Potentiometer

Various potentiometers from PCBs

In modern usage, a potentiometer is a potential divider, a three terminal resistor where the position of the sliding connection is user adjustable via a knob or slider. Potentiometers are sometimes provided with one or more switches mounted on the same shaft. For instance, when attached to a volume control, the knob can also function as an on/off switch at the lowest volume.

Ordinary potentiometers are rarely used to control anything of significant power (even lighting) directly due to resistive losses, but they are frequently used to adjust the level of analog signals (e.g. volume controls on audio equipment) and as control inputs for electronic circuits (e.g. a typical domestic light dimmer uses a potentiometer to set the point in the cycle at which the triac turns on). Potentiometers used to control high power are normally called rheostats.

[edit] Capacitors

Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. Major scale divisions are cm.

Capacitors are often used in electrical circuit and electronic circuits as energy-storage devices. They can also be used to differentiate between high-frequency and low-frequency signals. This property makes them useful in electronic filters.