Elenco Electronic Playground 50-in-1 Experiments - Manual (Page 9)

-9-
Press the switch (next to springs 55 and 56) and the LED
(light emitting diode) lights up, and turns off when you
release the switch. The LED converts electrical energy
into light, like the light bulbs in your home. You can also
think of an LED as being like a simple water meter, since
as the electric current increases in a wire the LED
becomes brighter. It is shown here, with its symbol.
Take a look at the water diagram that follows. It shows
the flow of water from the pump through the faucet, the
small pipe, the water meter, the large pipes, and back to
the pump. Now compare it to the electrical diagram next
to it, called a schematic. Schematics are the “maps” for
electronic circuits and are used by all electronic
designers and technicians on everything from your
Electronic Playground to the most advanced
supercomputers. They show the flow of electricity from
the battery through the switch, the resistor, the LED, the
wires, and back to the battery. They also use the symbols
for the battery, switch, resistor, and LED that we talked
about. Notice how small and simple the schematic looks
compared to the water diagram; that is why we use it.
Now you will see how changing the resistance in the
circuit increases the current through it. Press the switch
again and observe the brightness of the LED. Now
remove the wires from the 10K
Ω resistor (springs 44 and
45) and connect them to the 1K
Ω resistor (springs 40 and
41). Press the switch. The LED is brighter now, do you
understand why? We are using a lower resistance (less
rocks), so there is more electrical current flowing (more
water flows), so the LED is brighter. Now replace the
1K
Ω resistor with the 100KΩ resistor (springs 51 and 52)
and press the switch again. The LED will be on but will
be very dim (this will be easier to see if you wrap your
hand near the LED to keep the room lights from shining
on it).
Well done! You’ve just built YOUR first electronic circuit!
Water Meter LED Symbol for LED
Water Diagram
On/Off
Valve
Water
Meter Rocks
Pump
Schematic