21-09-2013, 04:54 PM
MOBILE SHIELD
MOBILE SHIELD.pdf (Size: 103.49 KB / Downloads: 14)
Protect your mobile phone from greater sensitivity and enables the cir-
unauthorised use or theft using cuit with hand capacitance effect. Out-
this simple circuit. It can gener- put pulses from the oscillator are di-
ate a loud chirping sound when some- rectly given to trigger pin 2 of the
body attempts to take away the mo- monostable. The monostable uses a
bile handset. The added feature is that low-value capacitor C6, resistors R3
the circuit also works as a mobile and preset VR1 for timing.
charger. The output frequency of the
The circuit is powered by a monostable is adjusted using preset
step-down transformer X1 with recti- VR1 such that it is slightly less than
fier diodes D1 and D2 and filter ca- that of the astable.
The warning LED1 and buzzer are put leads. Make the protective shield
connected such that they become ac- using 10cm×10cm copper-clad board
tive only when the output of the or aluminium sheet. Connect it to
monostable sinks current. In the the circuit using a 15cm plastic wire.
standby state, the LED1 remains ‘off’ Leads of all capacitors should be
MOBILE SHIELD.pdf (Size: 103.49 KB / Downloads: 14)
Protect your mobile phone from greater sensitivity and enables the cir-
unauthorised use or theft using cuit with hand capacitance effect. Out-
this simple circuit. It can gener- put pulses from the oscillator are di-
ate a loud chirping sound when some- rectly given to trigger pin 2 of the
body attempts to take away the mo- monostable. The monostable uses a
bile handset. The added feature is that low-value capacitor C6, resistors R3
the circuit also works as a mobile and preset VR1 for timing.
charger. The output frequency of the
The circuit is powered by a monostable is adjusted using preset
step-down transformer X1 with recti- VR1 such that it is slightly less than
fier diodes D1 and D2 and filter ca- that of the astable.
The warning LED1 and buzzer are put leads. Make the protective shield
connected such that they become ac- using 10cm×10cm copper-clad board
tive only when the output of the or aluminium sheet. Connect it to
monostable sinks current. In the the circuit using a 15cm plastic wire.
standby state, the LED1 remains ‘off’ Leads of all capacitors should be