Thanks for the repeater mod help from my other thread.

Here is a new challenging task given by me. i am using a hanger (like a hook) to hang a key.

How can i make switch or any solutions that i can achieve below procedure:

1) a key hanging to the hook will open the circuit.

2)When anyone remove the key, it will closed circuit(complete circuit) and my
transmitter will be activated.

3) here is what i am stuck with since i have closed the switch, the transmitter will keep on transmitting thereby wasting power UNTIL i return the key. how can i open up the circuit again WITHOUT hanging back the key.

4) Key returns and it STILL a open circuit and back to step 1.

Any method/ solution are welcome. If your answer is a pressure switch, please explain me how it works. i have never use it before.

Thanks a lot.

 

You can use a small limit switch on the hook to sense that the key has been removed and then use a timer (may a 555) to switch off the transmitter after a while.

 

Is the switch u mention this :
http://sspwa020.sp.edu.sg/student/E.../Image/5.32B8?OpenElement&FieldElemFormat=gif

The 555 timer schematic for delay as in below correct?
http://www.electronics-lab.com/projects/motor_light/042/fig-4.gif

 

Yes, i am talking about this switch. As for the circuit this works on an astable mode, you have to build a monostable circuit.
Look here for more information:

http://www.kpsec.freeuk.com/555timer.htm

 

Does this circuit work for me?
http://www.kpsec.freeuk.com/projects/timer.htm

i know i don't need the red LED and buzzer .

All i want is the a lever switch connect to the 555 switch and output my transmitter.

however if my transmitter have 9V battery. how can i use it also for the 555 timer? i mean combine them all up? hope you get me

 

Just connect the 555 circuit and the transmitter on the same 9 volt battery.