Normally-closed switch to turn on LED - HOW?

Hello,

I'm having problem building a circuit that meet my requirement below;

3 normally closed switch attached to each door (1 switch for 1 door) in my house, whenever one of the door opens, a Red LED light will turn on and stays on even the door had been re-closed. Same goes with other 2 switch.

Reason: I want to built a circuit whereby I could know which door had been open in my house. To avoid an intruder to get into my house.

I try to combine these 3 normally-closed Switches with 3 red LED powered by 9V battery. But failed

Can somebody draw me a simple diagram on how can I achieve it?

PS: I already manage to make 1 circuit with 3 normally-closed switch triggered alarm/siren whenever a door is open but not able to fit in LED lights to indicates which door had been open. So I decided to do seperate circuit, 1 for alarm/siren, 1 for Red LED lights to indicates which door had been open. Below are my success circuit (Thanks to Ron J).


Thanks A lot

Azhan

Malaysia

One way is to connect an RS flip-flop to each door switch. This is the basic memory circuit. Uses two transistors and a few resistors.

It has two inputs. A pulse at input #1 sets it. After the pulse is ended it makes no difference, the circuit remains in that state. If you apply further pulses at input #1, it remains in that state.

To make it change state, you must apply a pulse at input #2.

The states are symmetrical. Set and Reset are mere nomenclature.

To get a signal to feed to the rest of your circuit, you would tap at one of the transistors.

Try this additional circuit...........