how to make a light blink?

[par0thead151]

my car alarm has a led but it remains on constantly when armed, it doesnt blink. what do i need to make it blink, circuit wise.

also, what can i use to lower the voltage from a source ot make a fan revove slower?
like a resistor?
its 12 V and i want it to be around 50-75% of that to the fan so it will be quieter....

 

[plot]

a resistor work, what size depends on how how much current the fan takes normally.

as for blinking, something like a cap would work. im sure someone here has a simple schematic on hand...

 

[Boki]

For the flashing LED, there are few choices:
1.555 timer. Look up on the google for the simple schematic.

2.U could try to use PUT (programmable unijunction transistor) instead of 555.

3. Use this circuit .It needs to be modified little bit.

4 .For the fan control, simple way is to get a matching rheostat. Or, since the rheostat is not that efficient, you could try general use NPN transistor to control voltage.
Check the schematic bellow

good luck

 

[Adisharr]

Blinking LED - you can buy them with the circuit built right in.

 

[cpemma]

Originally posted by Adisharr
Blinking LED - you can buy them with the circuit built right in.

Adisharr's answer may be by far the easiest. The alarm circuit probably has a transistor switch controlling a led & series resistor, check the voltage across both when armed, if it's 12v (or 5v) replace both with a 12v (or 5v) flashing led.

More fan control circuits here