I tried to design this without much success so any help would be appreciated.
A transistor circuit where initially in a 3-pin Bi-Color LED (Common Cathode), the red led illuminates.
When an external positive voltage is applied (for example 5V), the red led switches off and the green led illuminates.
for example: initial state: external voltage 0V -> red led on, green led off
external voltage changes to +5V -> red led goes off, green led turns on
if the external voltage changes back to zero it resets the leds to the initial state.
A transistor circuit where initially in a 3-pin Bi-Color LED (Common Cathode), the red led illuminates.
When an external positive voltage is applied (for example 5V), the red led switches off and the green led illuminates.
for example: initial state: external voltage 0V -> red led on, green led off
external voltage changes to +5V -> red led goes off, green led turns on
if the external voltage changes back to zero it resets the leds to the initial state.