How-to identify and locate information for electronics components you can recycle from discarded gadgets. Brandon gives us example pictures and descriptions for most types of electronics components to help you stock up your home electronics lab. This is a must read for new electronics hobbyist.
The focus will be on common reusable through-hole components hobbyists will be most likely to scrounge and re-use.
Obviously, this is by no means a complete list, there are way to many different electronic components to put into a quick guide, but maybe this will give you some ideas to narrow down your search on an elusive component.
Resistors are one of the most used components in a circuit. Most are color coded, but some have their value in Ohms and their tolerance printed on them. To identify values, you can check out the Electronic Assistant software found in the Free Electronics Hobby Software article here on uC Hobby, or find one of the many online tools. A multimeter that can check resistance can also be helpful, providing the resistor is already removed from the board (measuring it while still soldered in can give inaccurate results, due to connections with the rest of the circuit). They are typically marked with an “R” on a circuit board.
Potentiometers are variable resistors. They normally have their value marked on them, normally marked with the maximum value in Ohms. Smaller trimpots may use a 3-digit code where the first 2 digits are significant, and the 3rd is the multiplier (basically the number of 0′s after the first 2 digits). For example, code 104 = 10 followed by four 0′s = 100000 Ohms = 100K Ohms. They may also have a letter code on them indicating the taper (which is how resistance changes in relation to how far the potentiometer is turned). They are typically marked with an “VR” on a circuit board.
Capacitors are also very commonly used. A lot have their values printed on them, some are marked with 3-digit codes, and a few are color coded. The same resources listed above for resistors can also help you identify capacitor values. They are typically marked with an “C” on a circuit board.
Inductors, also called coils, can be a bit harder to figure out their values. If they are color coded, the resources listed for resistors can help, otherwise a good meter that can measure inductance will be needed. They are typically marked with an “L” on a circuit board.
Crystals and Oscillators are also fairly easy to identify by sight. Most are clearly marked with their operating frequency printed on them. They are typically marked with an “X” or a “Y” on a circuit board.
Relays are typically enclosed in plastic, and many have their specs printed on them. They are typically marked with an “K” on a circuit board.
Transformers are normally pretty easy to identify by sight, and many have their specs printed on them. They are typically marked with an “T” on a circuit board.
Batteries are also pretty easy to identify, and are well marked with their specs.
Fuses can be easy to identify, and typically have their voltage and amperage rating marked on them.
Semiconductors, such as Diodes (typically marked with an “D” on a circuit board).
Transistors (typically marked with an “Q” on a circuit board),
Bridge Rectifiers (typically marked with an “BR” on a circuit board)
Integrated Circuits (typically marked with an “U” or “IC” on a circuit board), can take a little more work to figure out what they are. Many different types can use the same packaging, so they all can’t be identified by just their looks. In most cases the information you need is found in the device’s datasheet. The datasheet is a document containing the specs on the device and many will include example circuits, links to app notes, and other valuable information. They are typically in a .PDF format. If you have never used a PDF file before, you will need a PDF reader to open it. A couple of free ones can be found below.