Salvaging is like treasure hunting: You never what you’re going to get. Best of all, you’re saving money, recycling, learning, and amassing an armory of useful bits that may someday find purpose a in a DIY electronics project. Let’s face it, having an assorted collection of supplies tickles some primal human urge to hoard, and it feels great! What LEGO builder doesn’t dream of having organized bins of blocks sorted by color and shape?
Safety
As boring as prioritizing safety above the actual meat may be, losing an eye is a good way to forget any future salvaging expedition. With that said, be sure to invest in a pair of quality goggles – you don’t want them fogging up or slipping off your face in the middle of cutting, soldering, or drilling. Additionally, protective gloves, jeans and steel toe boots also come in handy when exploring scrapyards and the like.
Always work in a well-ventilated area next to an exhaust fan, preferably outdoors. PCBs emit a foul odor when burning that lingers for a long period of time, and the odor may be toxic.
Be careful with batteries and main power supplies. Batteries can explode when heated, and power supplies often retain large voltage charges inside, even if unplugged.
The right bag of tools
• Screwdriver: Obtain a set of variably sized screwdrivers; they are among your most useful tools for salvaging.
• Vice grips : Useful for holding electronics when de-soldering or applying the blow torch.
• Pliers: This tool simplifies the burden of unwinding springs and coils. Its grip can provide leverage when removing screws.
• Wire cutters: Self-explanatory; wire cutters clip any wires or cables you encounter.
• Wire strippers: Strip the rubber coating off of wires.
• Soldering Iron: The most useful tool in removing electronic components off of circuit boards.
• Solder wick: The wick aids in the removal of solder from PCBs.
• Multi-Meter: Checks batteries and other components for voltage.
• Oscilloscope: Enables the viewing of the exact wave shape of an electrical signal.
• Propane torch: Pertinent to mass de-soldering, more on this below.
Best places to salvage
Scrapyards and recycling plants are the Disneyland of salvaging. These locations are ideal for either collecting mass low-index components such as capacitors or finding tons of advanced components like stepper motors. You’ll find a vast array of discarded goods here ripe for the picking, although motorized components may not always function.
Tons of working printers are discarded due to the high cost of printer ink.
Mom’n’pop–style electronics repair shops are a dying breed, but an excellent source for vintage electronics and rare components, given the clientele are often of a less wasteful generation.
What to cannibalize
Household appliances are very useful: Look out for old printers, computers, computer hardware, DVD-players, motorized toys, electric tooth brushes, fax machines, modems, washing machines, and refrigerators.
• Transformers: Self-explanatory.
• Lithium-Ion Batteries: All around useful, these items are found in old mobile phones.
• Motors: Useful in all sorts of projects, especially robotics. You’ll eventually amass a large collection of different types. Look out for stepper, high-speed, and geared motors. Printers and electronic tooth brushes are an excellent source of motors, and the junk market is high for new printers given the expensive nature of printer ink.
• Connectors: Your wire cutters will be crucial for obtaining these. Connectors can be found inside computers and computer hardware, headphones, USB cables, RCA cables, etc. The wire stripper makes it possible to strip rubber coating off the ends to reuse them.
• ICs, capacitors, and resistors: These can be cheaply purchased in huge bulks for relatively cheap. ICs may be of greater value here
• Regulators: LM7805, LM7812, LM7905, LM7809, etc, are somewhat expensive to purchase, but freely available in discarded electronics. Given they sheer volume, they are one of your best finds.
• SDRAM chips: Look out for the nonvolatile variety with built-in battery backup; salvaging these chips will save you lots of money given their propensity to be expensive.
• Large electrolytic capacitors: 16-40v/6800-100.000uF capacitors are useful for repairing power amplifiers and power supply units.
• Speakers: The speakers inside stereo-TV’s are an excellent balance of size and quality; useful for radio projects.
• LEDs and LCD screens: It’s not uncommon for a project to contain an LCD screen or an LED or two. Most newbie projects involve lighting LEDs.
• CRT monitors: While these items are challenging for novices to work with, at risk of getting a nasty shock, they contain laminated copper wire a few hundred feet in length.
• Screws and bolts: Sort them by size as they are universally useful in most things.
• Buttons: Do not overlook the importance of buttons, as they will undoubtedly find their way back into your projects.
How to remove these things
The screwdriver set and soldering iron are the most useful tools as they are capable of removing majority of these components. Be sure to keep a wet towel on hand to clean off the soldering iron.
Feeling lucky, punk? Well do ya? Then try a blow torch (propane torch)
Blow torches have the potential to drastically reduce the time spent desoldering; however, using the tool runs the risk of destroying your components.
To commit mass desoldering using a blow torch, first clamp the PCB using a vice grip. Next, run a low blue flame behind the component at a distance approximately half an inch from the board. Simultaneously apply light pressure using tweezers or pliers to remove the components. The parts will typically detach so quickly that the traces aren’t even damaged and the part is barely warm.
Blow torching takes repetition before the balance of flame exposure and distance is determined, so be sure to practice on a couple of PCBs. Be aware that certain PCBs may respond differently to the heat, causing them to smoke and burn. Additionally, PCBs release toxic fumes whose smell linger a very long time. As previously stressed, be sure to work outside or use an exhaust fan to counteract this.
Sort, sort, sort!
Use plenty of bins and cardboard boxes to store and organize your booty. Remember, there’s no point in going through the motions of salvaging all this loot if working with it is drudgery. Most component types are labeled right on the board from whence they came. It’s worth noting this information to be able to identify what type of component it is. For example, are we dealing with a MOSFET or IGBT?
To learn how to design and develop motor control applications with NXP MagniV MCUs using model-based design, register for the free webinar, sponsored by NXP
Advertisement
Learn more about Digi-Key
