by Daniel Bartlett
So, you want to fill your hobby electronics drawers
with parts galore and don’t have the money to start?
Well, worry no more, as I am about to teach you how to
scrounge for those parts.
To scrounge is to forage about in an effort to
acquire something at no cost, and this process can
be very easily adapted to electronics as a result of the
myriad of broken appliances we find due to the
advent of the throw-away society. Computers, televisions, radios, car consoles, you name it — we throw it
away. Therefore, electronics hobbyists can have a
field day getting many normally expensive parts at little or no cost. However, there are a few “rules” to
scrounging, some of which are for your own safety
and others that will save you a lot of unnecessary
time and effort.
Rule 1: Anything acquired by scrounging is to
be considered broken and electrically hazardous.
Never plug into electricity any item that you have
scrounged (from whatever source) unless you know
exactly what you are doing; better yet, don’t do it at all.
These items were thrown away for a reason and have
the potential to electrocute anyone silly enough to energize them.
Also, take note of the fact that capacitors store
charges and have the potential (literally) to give you a
belting if you touch them or the circuit. Safe discharge
of these devices can be completed through the use of
an electrically insulated (1,000-plus-volt) screwdriver or
similar tool. Ask a qualified electrician for help in this
area if you are unsure. One area that I would never
dream of touching, by the way, is the back of a television picture tube. If the stored voltage isn’t enough to
hurt you, the explosion when you drop it and release a
pressure of 2,000-plus-psi surely will.
Rule 2: Only scrounge for rare or expensive
parts or something that you know that you will
need. There is no point desoldering four-cent, 1/4-watt
resistors or standard, small-value, ceramic/monolithic
capacitors, for example. You would pay more for solder
wick and the electricity to run your soldering iron than
APRIL 2005
you would for these parts. Instead, look for parts that
may seem rare or are known to be more expensive,
such as larger capacitors, Schottky diodes, pre-pack-aged diode bridges, microprocessors (Z80, EEPROM,
PIC), relays, and even large switches. These parts can
be worth $3.00-5.00 or more and are worth the time
and effort to desolder them.
The least amount of time you can spend on an
appliance the better, so you can re-throw it away and
get on to the next one. Each appliance provides its
own network of components; dwelling for too long on
one appliance only creates clutter by hoarding (an
unfortunate side effect of scrounging). Actually, one of
the best ways to find out the value of any particular
part is to have an electronics component catalog
handy, whether from the manufacturer or a retail
establishment (Dick Smith Electronics, RadioShack,
or similar). Although many of these companies only
sell common parts, the expensive ones can quite easily be identified.
Rule 3: Look for obvious signs of deterioration
on any particular part. If a capacitor has burst and
leaked all over the board, there is no point in scrounging it, as it will not work anyway. Other obvious signs of
deterioration include burning/overheating (
characterized by blackened areas and that smell), chemical
damage (caused by leaking capacitors, batteries, or
external fluids), water damage (obvious in itself), and
physical breakage (if the appliance has been dropped,
the board may have cracked in half, taking many components with it).
Much of this rule is simply common sense; if the
component looks broken, it probably is. However, if
you are unsure, there are measurement devices that
you can build or purchase that will give you a better
indication of the condition of a particular component.
These devices include multimeters (especially those
with a diode test function), transistor testers, capacitance leakage detectors, and others. Sometimes a part
may look perfectly fine, but may, in fact, be faulty
(for example, a transistor going open circuit).
Measurement devices can help you in this regard, but
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