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This design controls up to 8 devices using a PIC microcontroller
(PIC16F84A) connected to the phone line. The
unique feature here is that unlike other telephone
line based remote control, this device does
not need the call to be answered at the remote
end so the call will not be charged. This device
depends on number of rings given on the telephone
line to activate/deactivate devices.
Instructions for the telephone operated
remote switch:
A) While constructing the main circuit, make
sure you use 18pin sockets (base) for the PIC16F84A.
Do not solder the IC directly to the board since
you may have to remove it for programming. Before
you use the PIC on the main circuit, you have
to first program it.
B) To program the PIC16F84A microcontroller:
There are lots of programmers on the Internet
available to program PIC microncontrollers.
Given below are links to some free PIC programmer
hardware/software:
Note: Programm
the chip with the hex file attached above and
remember to set the fuse bits to use "EXTERNAL
HS OSCILLATOR" mode!
C) Remove the PIC from the programmer socket
and put it into the main circuit socket.
Set the DIP SWITCH as follows:
Switch3 Switch4 No.
of initial rings to Switch ON(activate half
of the board)
OFF OFF 5
ON OFF 4
OFF ON 3
ON ON 2
The number of initial rings to Switch OFF
is one more than the number of rings to switch
ON. For example, if you have set switch3 OFF
& Switch4 ON then number of initial rings
to activate half of the board to switch ON the
relays is 3 and number of initial rings to activate
half of the board to switch OFF the relays is
3+1 = 4
Switch1 Swtich2 Delay
before making the second set of rings
OFF OFF 20sec
ON OFF 15sec
OFF ON 10sec
ON ON 5sec
This is the maximum delay the board can take
after it is half activated. It will reset after
this delay.
D) Now connect the circuit to the phone line
and switch on its power supply.
E) You can test the board now. For example
set the DIP switch to Switch1 ON, Switch2 OFF
(15 sec delay) & switch3 ON, switch4 OFF
(4 rings to activate half for switching ON).
If you want to switch ON relay 1 (connected
to RB0 of main circuit) then you have to do
the following:
- Give 4 rings and put down the receiver
- Wait 5 seconds (this 5 seconds wait
is required to prevent the board from detecting
continous rings)
- then within 15 seconds give 1 ring (1
ring for relay1, 2 rings for relay2 and
so on) and put down the receiver
- then within 5 sec the relay1 will switch
ON
To switch off relay1:
- Give 5 rings and put down the receiver
- Wait 5 seconds (this 5 seconds wait
is required to prevent the board from detecting
continous rings)
- then within 15 seconds give 1 ring (1
ring for relay1, 2 rings for relay2 and
so on) and put down the receiver
- then within 5 sec the relay1 will switch
OFF
IMPORTANT: This
circuit has been tested by me and found to work
correctly. I cannot guarantee that the circuit
will work at your end since it depends on error
free construction and usage. Please do not contact
for any support and requests, any such requests
will not be entertained.
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