Category Archives: Alarms

Cellphone Operated Toggle Switch

Aussiemike in Kenya¬†– who suggested that light from a mobile phone’s display screen could be used to trigger a switch. When a brief (free) phone call illuminates the display – the light from the display operates a 4017 based¬†Toggle Switch. And any small push switch – connected in parallel with the LDR – will provide optional manual control.

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Touch triggered alarm

No description availableParts:1x Potentiometer 100 K
1x Resistor 100 K Not
1x Resistor 56 K Not
1x Resistor 10 M Not
1x Resistor 220 K Not
1x Capacitor 47 uF at 16 V Not
1x Capacitor 33 uF at 16 V Not
1x Transistor 2N3904
1x Diode 1N4004
1x IC LM555
1x Relay