N
Navid Naghdi
CUT PHONE LINE DETECTOR SCHEMATIC
Since nearly many electronics enthusiasts have been asking for
a schematic of a cut Telephone line detector, I decided that I
should contribute something that is of interest.
HOW IT WORKS:
When a cut phone line has been detected, a MOSFET is activated
which drives a relay, motor, etc. It also too can be connected
to a security system.
CONSTRUCTION SCHEMATIC:
_________o_______ +9V
| |
| __|___
R4 | Load |
| ------
| __|
| | Q3
o--------|<--.
b |/ e |___|
----| Q2 |
Q1 | |\ c |
|/ c | |
Green ----R1--------o----| | |
| | b |\ e | |
R2 | | | |
_|_ --- | | |
C1 === /_\ D1 | | |
| | | | |
Red __________o____o_____o______o____________o__ GND
COMPONENTS LIST
R1, R2, R3 3 22 Meg 1/4 W Resistor
R4 1 2.2 Meg 1/4 W Resistor
C1 1 0.47uF 250V Mylar Capicitor
Q1 1 2N3904 Transistor 2N2222
Q2 1 2N3906 Transistor
Q3 1 IRF510 Power MOSFET
D1 1 1N914 Diode
Load 1 See "Notes"
MISC 1 Wire, Phone Connectors, Circiut Board
Notes
1. The "Load" can be a relay, lamp, motor, etc. The circuit can also
be connected to a security system to sound an alarm in case the phone
line is cut.
2. If the circuit is connected to a security system or other circuit,
both circuits must be electrically isolated from each other using an
opto-isolator, relay, etc. This also means that the Cut Phone Line
Detector must be powered by a seperate 9V supply.
Since nearly many electronics enthusiasts have been asking for
a schematic of a cut Telephone line detector, I decided that I
should contribute something that is of interest.
HOW IT WORKS:
When a cut phone line has been detected, a MOSFET is activated
which drives a relay, motor, etc. It also too can be connected
to a security system.
CONSTRUCTION SCHEMATIC:
_________o_______ +9V
| |
| __|___
R4 | Load |
| ------
| __|
| | Q3
o--------|<--.
b |/ e |___|
----| Q2 |
Q1 | |\ c |
|/ c | |
Green ----R1--------o----| | |
| | b |\ e | |
R2 | | | |
_|_ --- | | |
C1 === /_\ D1 | | |
| | | | |
Red __________o____o_____o______o____________o__ GND
COMPONENTS LIST
R1, R2, R3 3 22 Meg 1/4 W Resistor
R4 1 2.2 Meg 1/4 W Resistor
C1 1 0.47uF 250V Mylar Capicitor
Q1 1 2N3904 Transistor 2N2222
Q2 1 2N3906 Transistor
Q3 1 IRF510 Power MOSFET
D1 1 1N914 Diode
Load 1 See "Notes"
MISC 1 Wire, Phone Connectors, Circiut Board
Notes
1. The "Load" can be a relay, lamp, motor, etc. The circuit can also
be connected to a security system to sound an alarm in case the phone
line is cut.
2. If the circuit is connected to a security system or other circuit,
both circuits must be electrically isolated from each other using an
opto-isolator, relay, etc. This also means that the Cut Phone Line
Detector must be powered by a seperate 9V supply.