This alarm is very simple to build and operate, because it is controlled by a key switch - it doesn't have complicated timing circuits and setting procedures like many other alarms: a great way to learn the basics. A key switch looks just like the ignition switch in a car: you turn the key one way and the switch is on; back the other way and the switch is off. Key switches are normally installed on or near the front door of the house or, in the case of a car, on the door or hidden somewhere within the vehicle.
What You Need
Resistors:
R1 220k ohms
R2 100k ohms
R3 1.2M ohms
R4 100k ohms
R5 47k ohms
Capacitors:
C1 0.01uF MKT polyester
C2 0.01uF MKT polyester
C3 0.1uF MKT polyester
C4 22uF 16V tantalum
C5 0.01uF MKT polyester
C6 1000uF 16/25V electrolytic
Semiconductor Devices:
D1 1 N4004 diode
D2 1 N4004 diode
D3 1N4004 diode
TR1 BC548 NPN transistor
IC1 LM555 / NE555 timer integrated circuit
Miscellaneous:
RLY1 1 Miniature relay with 9V coil, single change over contacts.
Solder, hook-up wire, battery snap & printed circuit board (code ZA1635B).
You will also require a common 9 or 12 volt battery of reasonable capacity (two 9V alkaline batteries in parallel, for example) or some other 9 volt DC power supply (not normally supplied with a kit).
Download the assembly manual for the K-2635 Home and Car Alarm here.