newbie question on idea

[cavionchrome]

ok heres what i'm wanting to make...i wanna make my own underbody LED kit..i have the led's and resistors..heres what i have a question on tho...i want to alternate colors in the tubes..blue white blue white etc....i want to hook blue to one circuit and white to another...what i want the system to do is switch from white to blue to white to blue back and forth not TOO fast but not too slow...without having to manually switch it back and forth..i'm looking for ideas on how to wire up an automatic switching device type thing...where all i need to do is switch on power..and it'll start changing back and forth....all help is greatly appreciated and if ya need more info i'll do my best...kinda have all this in my head..just don't know how to make it..i'l need a parts list and diagram if ya wouldn't mind..also where to get the parts..ie. radio shack? thanks alot in advance...later

Eric

[cavionchrome]

forgot to mention..this will be going on my truck..12volts..that mite help a lil...i have 400 led's...100 for each side and 100 for front and back...each led has a resistor for use in a 12v system.....also if ya have any sorta simple but cool idea's as to maybe like a fade on..fade off type thing to add to it..that'd be great..i'm getting my stepdad to help me wire everything up

[Guest Yevgenip]

You need a 555 Timer. when the output is positive, it will activate an NPN transistor that will turn on the LEDs. When the output is negative, it will activate a PNP tranistor that will turn on the other LEDs. This is very basic if you know how to use the 555 timer.

Good Luck.

[Guest]

How many LEDs are you going to use or how many you atleast
want to use?

How you want your source to be?

[Guest Alun]

The following circuits will both do what you want, the first is an astable built with 2 transistors BC547s will do fine. The frequency will depend on the orange 47K resistors and the capacitors, don't expect great stability the frequency will change with input voltage and loading.

The second is a 555 timer, the output can handle up to 200mA and both push and pull so you don't need any transistors to invert or buffer the load. This circuit is more stable and the frequency is independent of the load or power supply.

Both circuits demonstrate how the LEDs can be connected in both series and parallel.