great site.. we use RS at work, and they are always good with their delivery time..
you can buy kits too, not sure where from.. but i know you can get kits
or just make a simple circuit like this and have a bit of fun.. useful in the car
This circuit will flash a bright red LED (5000 mcd) as an attention getting device or fake car alarm. Component values are not critical and other transistors may be used. Flash duration is determined by R2 and C1 and is approximately 3 time constants (3*R2*C1). Brightness is controlled by R3 wich limits the LED current to about 20 mA for values listed. R1 provides bias for the transistors which should be low enough not to saturate Q2 with the capacitor disconnected. If the circuit does not oscillate, R1 may be too low or R2 may be too high. D1 allows for higher duty cycle operation and limits the reverse voltage at the base of Q1 to -0.7 V. D1 may be omitted for low voltage (3-9) and low duty cycle operation. Most parts available at Radio Shack.
Volts R1 R2 R3 C1 Approx. Flash Rate
12 10 Mohm 22 Kohm 470 ohm 0.47 uF 140 per minute
12 10 Mohm 10 Kohm 470 ohm 1 uF 60 per minute
9 6.8 Mohm 1 Kohm 390 ohm 6.8 uF 15 per minute
6 3.3 Mohm 10 Kohm 220 ohm 1 uF 80 per minute
3 1.5 Mohm 10 Kohm 51 ohm 1 uF 120 per minute
3 3.3 Mohm 47 Kohm 51 ohm 0.47 uF 140 per minute