Prepare the circuitry on the basis of the connection diagram. The circuitry is identical with the one used for measuring LED characteristics. Certainly, three distinct power supply sources may also be used. Change the voltage level and hence, the brightness of each LED using the potentiometer. Pending on their colour, the opening voltage level of the LEDs used in the experiments falls between 1.7 and 2.5 V. Readily available voltage sources have typically 1.5 V, or an integer multiple. In other words a single 1.5 V penlight battery would be insufficient, two is too much. The load bearing capacity of these tiny LEDs is very low, therefore it is definitely necessary to use a preventive lead (switch resistance) to protect the LED which is usually connected to the circuit before the anode.

Implements required for the experiment

– String light red, green and blue LED
– Three 100 Ω metal film resistors as preventive leads to protect the LEDs
– Three potentiometers (10 kΩ, linear, multiple revolutions)
– 3 V power supply source
– Wires