14-10-2010, 01:32 PM
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Circuit Components
The circuit of invisible broken wire detector is a simple circuit which is built using a hex inverter CMOS IC CD4069. This IC has six inverters that is NOT gate. Out of these six inverters the gates N3 and N4 are used as a pulse generator that oscillates at around 1000Hz in the 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 half cycle, output pin 10 of gate N2 goes high.
