Elenco Basic Electronic Experiments - Manual (Page 23)

EXPERIMENT #11: MAKE YOUR OWN BATTERY
Connect the circuit according to the schematic and Wiring Diagram. Note that one side of the battery and resistor are
unconnected and there is a wire connected only to the 100
μF capacitor. At this time no current will flow because nothing
is connected to the battery. Now hold the loose wire and touch it to the positive battery wire and then remove it, the battery
will instantly charge the capacitor since there is no resistance (actually there is some internal resistance in the battery and
some in the wires but these are very small). The capacitor is now charged and is storing the electricity it received from the
battery. It will remain charged as long as the loose wire is kept away from any metal. Now touch the loose wire to loose
side of the 3.3k
Ω resistor and watch the LED. It will initially be very bright but diminishes quickly as the capacitor
discharges. Repeat charging and discharging the capacitor several times. You can also discharge the 100 μF in small
bursts by only briefly touching the 3.3k Ω. If you like you can experiment with using different values in place of the 3.3kΩ;
lower values will make the LED brighter but it will dim faster while with higher resistor values the LED won’t be as bright
but it will stay on longer. You can also put a resistor in series with the battery when you charge the capacitor, then it will
take time to fully charge the capacitor. What do you think would happen if you used a smaller capacitor value?
When the capacitor is charged up it is storing electricity which could be used elsewhere at a later time - it is like a battery!
However, an electrolytic capacitor is not a very efficient battery. Storing electric charge between the plates of a capacitor
uses much more space than storing the same amount of charge chemically within a battery - compare how long the 100
μF
lit the LED above with how your 9V battery runs all of your experiments!
Now is a good time to take notes for yourself on how capacitors work, since next we introduce the diode.
23
+9V
3.3k
Ω
100 μF
(UNCONNECTED)
(LOOSE WIRE)
(UNCONNECTED)
+
-