I have a circuit of 4 light bulbs, with single switch on the positive terminal that will turn all the 4 bulbs at once. EDIT: Light bulbs circuit is parallel design. source is 12V DC and all bulbs are running 12V DC.
I want to be able to still have the original switch to turn on all 4 bulbs, with a new switch that overrides bulb #3 to keep it turning on. Essentially, when bulb #3 is switched on, the original switch ignores bulb #3.
To solve this I go with installing a diode at the positive terminal of the bulb #3. When original switch is on, electricity will go thru that diode and then turns the bulb on; when new switch is turned on, electricity will go to bulb #3 thru new line but will not go to the original circuit because of the new diode.
A friend said this might be able to be done with a transistor but he couldn't figure out the solution. Is that true we can use transistor for this? it's for automotive brake lights.