Need help - Just want to make a simple switch using RF Modules

[Macgman2000]

I did a design a while back where the TX needed to be completely off for max battery life. I used a n-channel FET and I/O pin to enable the pic to strap itself on while the tx button was pressed, once released the code saw the falling edge and transmitted the off data. After that the pic turned itself off.

[financecatalyst]

I did a design a while back where the TX needed to be completely off for max battery life. I used a n-channel FET and I/O pin to enable the pic to strap itself on while the tx button was pressed, once released the code saw the falling edge and transmitted the off data. After that the pic turned itself off.

In the circuit I have, the Transmitter module gets full 12V(via LR23 battery) and Tx gets 5V via 7805. The circuit only completes upon when button is pressed. Any sugesstion for making any change to the hardware part i.e. at the output pin of the Rx. I am having a feeling now that this problem cannot be solved via software!!

[Macgman2000]

Ok I am missing something......you posted a couple of posts ago the following....

Problem is that the Tx only gets power while the button is pressed once button is released, power is also removed from the pic. Is there any way I can achieve my goal using an capacitor or somthing at the output in the hardware as I dont seem to figure out an solution with software (Unless someone comes up with somthing I can try on my exsisting setup). I already tried using an 470uF at the output pin + replacing 1K wih an diode. I am having problem with timings now BUT flickering seems to have been absorbed by the capacitor. If possible any sugesstion about the cap values I can try to have instant responses by the receiver PIC?

So I came back with my design for a FET transistor supplying power as long as it takes to transmit an off command when you let go of the button. This should solve your issue. Especially since you have two different voltage sources, your N-channel FET would go between your common grounds, to essentially switch ground on or off. Just imagine it as a switch that cuts your circuit off at the ground side.

If you use a 100uF cap at the + side make sure that there is a resistor in parallel with the cap that will discharge it when the FET cuts off ground.

Nick

[financecatalyst]

hello Macgman200, can I please please request you to draw me a simple schematic for what you are saying. I am not very expert in this domain. Looks like you are talking a practical solution! Many thanks