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.
The Travel Touch Alarm can be used to provide a audible alarm when someone touches the door knob or handle of your hotel room.
The Sun – Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc.
This alarm circuit is based on two 555 timers. The alarm will sound your car horn if anyone opens the car door while the circuit is armed.
This circuit is very basic to build. To open a the lock which is connected to the K1 Load you must press each momentary switch in the correct sequence.
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