Instructions

23
11 A colour switcher
With a resistance of 2.2k Ω (red, red, red) and two LEDs, a
very special circuit is built – a green-red switch. Every time
you press the button, the red LED goes on, but the green LED
goes off.
When the switch contact is closed, it is actually a normal
parallel connection like in Experiment 6. But in that exper-
iment similar LEDs were used; this time they are different.
The green LED needs a higher voltage than the red LED. When
the red LED is turned on, the voltage drops so low that the
green LED can no longer shine. This is how changing colours
is created.