Alternate Flashing LED's

Stormvet · #1 11-17-2003, 02:24 AM

OK, I have seen a lot of post on here about flashing LED's for police & fire vehicles. Keep in mind I am definitely not an expert in electronics! I searched for some circuitry on alternate flashing LED's and came up with the following:

2 - 470 Ohm, 5% Tolerance resistors
2 - 39K Ohm, 5% Tolerance resistors
2 - 10uF / 16V Capacitors
2 - Transistors (Radio Shack #2N3904)
2 - LED's (you pick the color)

When properly assembled, these components will make alternate flashing LED's and are quite impressive in an X-MOD. The attached pic shows both lights on but they do alternate and look x-tremely cool!

I have a few pictures of the wiring of the components but do not have the photos of them in my RSX yet.

If anyone is interested I will find the link to the website again and post it.

Good luck with your MODS!

TypeZer0 · #2 11-17-2003, 09:27 AM

wow, that circuitry looks quite simple. ph2t has been working on one (dunno the status of it now) and he was using an OP-AMP to generate a square wave to make it flash. coudl you post teh schematic or the link to the site with the schematic? how fast does it flash>

Stormvet · #3 11-17-2003, 12:04 PM

I will search for the schematic and post it today. The LED's on my RSX flash at a rate of about 1 cycle per second (this rate is determined by the 39K Ohm resistors and can be changed easily).

Here are some pics of the LEDs in my RSX (Not a lot of mods yet).

Stormvet · #4 11-17-2003, 12:13 PM

I found the schematic again. It came from this websit:
http://www.uoguelph.ca/~antoon/circ/flash2.htm

dragon4450 · #5 11-17-2003, 01:50 PM

i wonder how hard it would be to add a 3rd led into that and make it flash aside from the rest of them. you know like have a random flashing patern for 3 leds.

Chettaman · #6 11-18-2003, 11:28 AM

That is a great pic of how you wired it up, but how do you do it? Is possible to get a step by step guide on how to wire this up and what differences the different capacitors and resistors make? Thanks.

Stormvet · #7 11-18-2003, 11:55 AM

I'm going to be doing another one for a buddy so I will take step by step notes and photos when I do it.

Should be pretty soon (within the next week).

Thanks!

richh · #8 11-18-2003, 12:32 PM

quick question... do the led's simply alternate left, right, left, right? or is there a point where they are both on before one turns off?

TypeZer0 · #9 11-18-2003, 01:26 PM

the transistors act like on/off switches and from what i can tell, they won't turn on together

Stormvet · #10 11-18-2003, 04:41 PM

They alternate left and right. They are never really "ON" together. There may be a little bit of bleed over while the light is going away (hence the picture where they look like they are both on) but they are not.

I hope this helps.

truckian · #11 11-18-2003, 11:03 PM

Are you supposed to use 39Kohm or 3.9Kohm resistors. Because at Radioshack all they had were 3.9Kohm resistors.

Edit: also, how do you power the lights? Do you somehow hook them up to the car battery? Pics would be appreciated.

Stormvet · #12 11-18-2003, 11:58 PM

You might need to check a couple of different Radio Shacks. The resistors are supposed to be 39K Ohm. I ended up using 33K Ohm resistors because the RS I went to did not have the 39K except for in an assortment pack for $11.99

As for the power... I hooked it up to the power leads coming up to the motor plug and it worked as follows:

on High Trim the lights would alt flash as they are supposed to. The lower setting made the lights flash much faster (almost strobe). This is the reason that I am working on an alternate power source. I originally configured this for a 9V circuit but there is no room under the body for a 9V. The obvious would be to reduce resistors to allow for less voltage (6V) but I want to ensure that there will not be a change in the flash rate from high to low trim. Therefore; I am still searching for an additional power source (aside from the battery pack of the XMod).

I hope this information is helpful.

wasuri · #13 11-19-2003, 01:23 AM

WOW! im going to have to do this now. Since the skyline has the 2 different lights in the back (backup lights) it would be really cool to have two of them! Maybe even a backup light that works when you backup? hmmm a project bc?

HotCar · #14 11-19-2003, 01:50 PM

for an alternate power source u could use two 3v watch batteries(panasonic cr2016), i took apart a LED keychain that was really bright and that is what powered that. it gives you 6v of power, but takes up less than .5 cm of space.

TypeZer0 · #15 11-19-2003, 03:56 PM

one of those shoudl be fine, 6 volts kills some led's