# Light sensing A or B switch

#### MercilessMike

Joined May 31, 2013
2
I've racked my brain to come up with a simple 12VDC circuit to determine which strand of LED ribbon to turn on.
Here's the plan:
When here is ambient light (day time) and I open a door (reed switch) the High Output LED strand is turned on.
When there is low light and door is opened, the red strand is turned on.

I see using a photo resistor circuit, but the OR gate logic eludes me.

#### LDC3

Joined Apr 27, 2013
924
I've racked my brain to come up with a simple 12VDC circuit to determine which strand of LED ribbon to turn on.
Here's the plan:
When here is ambient light (day time) and I open a door (reed switch) the High Output LED strand is turned on.
When there is low light and door is opened, the red strand is turned on.

I see using a photo resistor circuit, but the OR gate logic eludes me.

You want to use an AND gate, not an OR gate.
1) Bright AND Door Opens
2) Dim AND Door Opens

#### MercilessMike

Joined May 31, 2013
2
My initial idea was the reed switch act as a power switch for the circuit since it will be running of SLA batteries. I could add in a charging system to the SLA's from a solar panel.

#### LDC3

Joined Apr 27, 2013
924
My initial idea was the reed switch act as a power switch for the circuit since it will be running of SLA batteries. I could add in a charging system to the SLA's from a solar panel.
You can still use the door open to power the whole system. Your conditions then become a choice of
1) Bright
2) Dim
True, it is now a choice of 1 or 2, but you will see that it is more like 1 or not 1. So your conditions are simpler than you thought.