This is a hack I did to make a wireless doorbell loud enough to be heard over loud equipment and to give a visual indication of which door button had been pressed. For the visual indication I used two 4 inch CCFL tubes and for the sound I used a compact Siren. For the doorbell I chose the GE wireless Door Bell with two wireless buttons.
This is what it looks like inside. The 14 pin IC is a 4011. By looking at the outputs of the NAND gates I found that Pin 4 Toggles with any button push and pin 10 toggles when I press the back door button. I chose to use a MicroChip PIC processor to decode the outputs to keep the parts count down and because I had them on hand. I started by attaching wires to the circuit board in the doorbell to pick up the signals from the CD4011 and provide power to doorbell from the decoder and drivers.
I built the circuit on a perf board and mounted it to a piece of angle aluminum. Every thing gets put into a circuit breaker box I stripped all the guts out of. Function: When Front door button is pressed the siren sounds for a set time leaving the white lamp on for a bit longer. When the Back door button is pressed the Siren sounds for a set time leaving the blue light on for a bit longer.
Results: The unit has performed well since it was connected. Couple changes I would like to make. 1) Install a connector on the Doorbell and the box so that the actual doorbell can be located in a different location than the box. 2) Clean up the program so that white lamp does not flash when the back door button is held down (not been a problem so far). 3) Clean up the power supply design.
;Door bell decoder
;Written for the PIC12C671 running in internal 4mhz mode.
;By W.H.- April 2006
;Define configuration bits.
__CONFIG _MCLRE_OFF & _CP_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
TIC, TEMP, SIGNAL, BEAT, OUTPUT,W_TEMP,STATUS_TEMP
;Define interupt vector
;Define code start
START CALL CALIBRATION
LOOP BTFSS GPIO,2
;Check to see if time is up.
CLEAR CLRF OUTPUT
;Interupt routine*****interupt every .0653seconds******
INTER PUSH ;Interupt routine
BCF INTCON,7 ;Turn off interupts
INCF TIC,F ;Increment time one
BTFSS TEMP,5 ;Toggle
MOVLW B’10100000′ ;Turn on interupt and clear flag.