Circuitry :
Portable loads such as video cameras, halogen flood lights, electrical
irons, hand drillers, grinders, and cutters are powered by connecting
long 2- or 3-core cables to the mains plug. Due to prolonged usage, the power
cord wires are subjected to mechanical strain and stress, which can lead to internal
snapping of wires at any point. In such a case most people go for replacing
the core/cable, as finding the exact location of a broken wire is difficult. In 3-core
cables, it appears almost impossible to detect a broken wire and the point of break
without physically disturbing all the three wires that are concealed in a PVC jacket.
The circuit presented here can easily and quickly detect a broken/faulty wire
and its breakage point in 1-core, 2-core, and 3-core cables without physically disturbing
wires. It is built using hex inverter CMOS CD4069. Gates N3 and N4
are used as a pulse generator that oscillates at around 1000 Hz in audio range.
The frequency is determined by timing components comprising resistors R3 and
R4, and capacitor C1. Gates N1 and N2 are used to sense the presence of 230V AC
field around the live wire and buffer weak
AC voltage picked from the test probe. The voltage at output pin 10 of gate N2
can enable or inhibit the oscillator circuit. When the test probe is away from any
high-voltage AC field, output pin 10 of gate N2 remains low. As a result, diode
D3 conducts and inhibits the oscillator circuit from oscillating. Simultaneously,
the output of gate N3 at pin 6 goes ‘low’ to cut off transistor T1. As a
result, LED1 goes off. When the test probe is moved closer to 230V AC,
50Hz mains live wire, during every positive halfcycle, output pin 10 of gate
N2 goes high. Thus during every positive half-cycle of the
mains frequency, the oscillator circuit is allowed
to oscillate at around 1 kHz, making red LED (LED1) to blink. (Due to the persistence
of vision, the LED appears to be glowing continuously.) This type of blinking
reduces consumption of the current from button cells used for power supply.
A 3V DC supply is sufficient for powering the whole circuit. AG13 or LR44
type button cells, which are also used inside laser pointers or in LED-based continuity
testers, can be used for the circuit.
The circuit consumes 3 mA during the sensing of AC mains voltage.
For audio-visual indication, one may use a small buzzer (usually built inside
quartz alarm time pieces) in parallel with one small (3mm) LCD in place of LED1
and resistor R5. In such a case, the current consumption of the circuit will be
around 7 mA. Alternatively, one may use two 1.5V R6- or AA-type batteries. Using
this gadget, one can also quickly detect fused small filament bulbs in serial loops
powered by 230V AC mains. The whole circuit can be accommodated
in a small PVC pipe and used as a handy broken-wire detector. Before detecting
broken faulty wires, take out any connected load and find out the faulty wire
first by continuity method using any multimeter or continuity tester. Then connect
230V AC mains live wire at one end of the faulty wire, leaving the other end free.
Connect neutral terminal of the mains
AC to the remaining wires at one end. However, if any of the remaining wires is
also found to be faulty, then both ends of these wires are connected to neutral. For
single-wire testing, connecting neutral only to the live wire at one end is sufficient
to detect the breakage point. In this circuit, a 5cm (2-inch) long,
thick, single-strand wire is used as the test probe. To detect the breakage point,
turn on switch S1 and slowly move the test probe closer to the faulty wire, beginning
with the input point of the live wire and proceeding towards its other end.
LED1 starts glowing during the presence of AC voltage in faulty wire. When the
breakage point is reached, LED1 immediately extinguishes due to the non-availability
of mains AC voltage. The point where LED1 is turned off is the exact
broken-wire point.
While testing a broken 3-core rounded cable wire, bend the probe’s edge in the
form of ‘J’ to increase its sensitivity and move the bent edge of the test probe closer
over the cable. During testing avoid any strong electric field close to the circuit to
avoid false detection.
Portable loads such as video cameras, halogen flood lights, electrical
irons, hand drillers, grinders, and cutters are powered by connecting
long 2- or 3-core cables to the mains plug. Due to prolonged usage, the power
cord wires are subjected to mechanical strain and stress, which can lead to internal
snapping of wires at any point. In such a case most people go for replacing
the core/cable, as finding the exact location of a broken wire is difficult. In 3-core
cables, it appears almost impossible to detect a broken wire and the point of break
without physically disturbing all the three wires that are concealed in a PVC jacket.
The circuit presented here can easily and quickly detect a broken/faulty wire
and its breakage point in 1-core, 2-core, and 3-core cables without physically disturbing
wires. It is built using hex inverter CMOS CD4069. Gates N3 and N4
are used as a pulse generator that oscillates at around 1000 Hz in audio range.
The frequency is determined by timing components comprising resistors R3 and
R4, and capacitor C1. Gates N1 and N2 are used to sense the presence of 230V AC
field around the live wire and buffer weak
AC voltage picked from the test probe. The voltage at output pin 10 of gate N2
can enable or inhibit the oscillator circuit. When the test probe is away from any
high-voltage AC field, output pin 10 of gate N2 remains low. As a result, diode
D3 conducts and inhibits the oscillator circuit from oscillating. Simultaneously,
the output of gate N3 at pin 6 goes ‘low’ to cut off transistor T1. As a
result, LED1 goes off. When the test probe is moved closer to 230V AC,
50Hz mains live wire, during every positive halfcycle, output pin 10 of gate
N2 goes high. Thus during every positive half-cycle of the
mains frequency, the oscillator circuit is allowed
to oscillate at around 1 kHz, making red LED (LED1) to blink. (Due to the persistence
of vision, the LED appears to be glowing continuously.) This type of blinking
reduces consumption of the current from button cells used for power supply.
A 3V DC supply is sufficient for powering the whole circuit. AG13 or LR44
type button cells, which are also used inside laser pointers or in LED-based continuity
testers, can be used for the circuit.
The circuit consumes 3 mA during the sensing of AC mains voltage.
For audio-visual indication, one may use a small buzzer (usually built inside
quartz alarm time pieces) in parallel with one small (3mm) LCD in place of LED1
and resistor R5. In such a case, the current consumption of the circuit will be
around 7 mA. Alternatively, one may use two 1.5V R6- or AA-type batteries. Using
this gadget, one can also quickly detect fused small filament bulbs in serial loops
powered by 230V AC mains. The whole circuit can be accommodated
in a small PVC pipe and used as a handy broken-wire detector. Before detecting
broken faulty wires, take out any connected load and find out the faulty wire
first by continuity method using any multimeter or continuity tester. Then connect
230V AC mains live wire at one end of the faulty wire, leaving the other end free.
Connect neutral terminal of the mains
AC to the remaining wires at one end. However, if any of the remaining wires is
also found to be faulty, then both ends of these wires are connected to neutral. For
single-wire testing, connecting neutral only to the live wire at one end is sufficient
to detect the breakage point. In this circuit, a 5cm (2-inch) long,
thick, single-strand wire is used as the test probe. To detect the breakage point,
turn on switch S1 and slowly move the test probe closer to the faulty wire, beginning
with the input point of the live wire and proceeding towards its other end.
LED1 starts glowing during the presence of AC voltage in faulty wire. When the
breakage point is reached, LED1 immediately extinguishes due to the non-availability
of mains AC voltage. The point where LED1 is turned off is the exact
broken-wire point.
While testing a broken 3-core rounded cable wire, bend the probe’s edge in the
form of ‘J’ to increase its sensitivity and move the bent edge of the test probe closer
over the cable. During testing avoid any strong electric field close to the circuit to
avoid false detection.
the led always remaining on ,with out eletric field also
ReplyDeleteno it doesn't
ReplyDeletecan u tell me y the led remains on.
ReplyDeletewhat did u use as a probe.
A small wire
ReplyDeleteJs like a plug box wire is enough i thnk,,,,,,,
certainly
ReplyDeletewhy we use only CD4069 IC . what are the use of all three diodes
ReplyDeleteBecause of :
ReplyDeletewide power supply operating range, low power consumption, high noise immunity, and symmetric controlled rise and fall times and ESD protection