User manual

25
12 Flashlight trio in sync
We will arrange the circuit now in a way that all three LEDs
will go fully dark in between the flashing cycles. We are going
to use a 1 kΩ resistance (brown, black, red). The red flashing
LED utilizes the transistor to turn the red and green LEDs on
and off. As a result, all three LEDs are flashing.
Remove the 1 kΩ resistor out of the circuit and you will see
that only the flashing LED will flash, the other two LEDs are
steady lit. The transistor amplification is large enough to keep
the remaining LEDs lit just by the small residual current of
the flashing LED. The 1 kΩ resistance is thus used to dissipate
this small current, so that the transistor conducts current only
if the flashing LED is in the on state. Together the three LEDs
flash much brighter than the flashing LED on its own. You just
observed how the transistor works as an amplifier.