smitty2919

This thread is not for the average joe I suppose as I have a ME degree and the basic knowldge of circuitry....this will prob get quite technical so I appologize for people wanting to do this but have NO clue what is being talked about.

That being said, I want to make my own for my 04 GT. Now, I know the inner light is a parking only light. I plan to add a brake/blinker wire tied in with the middle and outer lights (this light will not get a delay as it will be the first light on in the sequence).

Next step is delaying the middle and outer lights. I have looked into 555 timer's but I am still a little foggy on their exact function. From what I understood by researching is I would want them in Astable mode (sending signals periodically...becomes an oscillator). This would give me my desired on/off function. But the more I thought...I don't want the 555 to turn off my bulb...that will be taken care of by the blinker's Flasher under the steering column (expect I need to modify...more on that later).

So I am looking to use a simple resistor capacitor (RC circuit) design to delay my bulbs. It would be nice if I could get the sequence to blink within the allowable time from the stock flasher (which when all said and done my appear too fast). This is where the modified stock flasher comes in. I could either change the capacitor or the resistor to lengthen my blinking time.

I did some number crunching and guessed at these times/values:

For my middle delay of 1/2 sec, I would use a 10 microFarad capacitor with 10K ohm resistor. Giving me a time constant of .1 and a delay of .5sec (5 time constants)

For my outer delay of 1.5 sec, I would use a 10 microFarad capacitor with 30K ohm resistor. Giving me a time constant of .3 and a delay of 1.5sec (5 time constants)

I guessed at my .5 and 1.5 sec delay times and could be anything I want (within reason of available resistors/capacitors).

Would it be as simple as just to place my resistor/capacitor on my brake/blinker lead wires?? If so, I'm suprised no one has done this and still go to buy kits. I'm not a huge fan of the kits because they seem to make a hackjob wiring of your stock harness. My method I am only adding 1 wire (inner bulb) and splicing in a capacitor and resistor(for middle/outer bulbs)...

SORRY for long post. I have been talking with some people through PM's but this way everyone can have soe input. I plan to make this all from Radio Shack parts and to show everyone how to do it themselves if this becomes a success.

AustinBoston17

This seems like a really good idea!
Goodluck, I wish I knew about all that electrical junk

smitty2919

Yes, I may be missing something in my theory...but if not, this could be something anyone with even a little mechanical ability could do.

Many people may have went with the $50 kit for ease, but I don't mind using my brain cells and designing something. Especially when the $50 kit looks like a 2"x2" breadboard with some components covered by heat shrink material with 4 wires coming off of it...

devongarver

well, there was a guy who did it, and he used a programmable IC to do it. I'll tell ya what...I maybe, just MAYBE if I have time, I will stop digging a ditch for an hour this weekend and pull out my old school books and give this a crack. Honestly, this stuff is not fresh in my head as I have a terrible memory and need to constantly use something to remember it. Cliff would be a wise addition to this thread, may want to send him a PM invite eh'? I could always man up and cut open the kit I have installed, but it isn't normal heatshrink, its rock hard-so I don't know if I might not end up breaking something by opening it up you know?

stanged

I was trying to follow your explanation of what you might do. Did you intend to put the resistor in series with the lamp and the capacitor in parallel with the lamp with the intent to delay the illumination of the lamp? If so, I think the resistor will prevent the lamp from illuminating. A 10K resistor will limit the current in a 12 volt circuit to 1.2 ma, no where near enough to illuminate it. If I am wrong in understanding what you are planning, a simple diagram should help for us to make an intelligent comment.

smitty2919

Devon: I don't want you to go breaking anything of your's just to please me lol I'm the same way. I love doing little projects because a lot of the time I end up learning things I didn't know prior to the project. I hate to bother Cliff as I have already asked for help before on other stuff. So I'll just see if he pops in or not on his own.

Stanged: No I plan to put a resistor and capacitor in series ONLY on the power (brake/signal) wire of each bulb. I would get a non-polarized capacitor to be able to do this. Doing it this way would delay the flow until the capacitor is charged...then light up my bulb.

devongarver

smitty, I havent had a chance to look at anything yet, but do yuo have any electronics toys at home? like a test bread board or power supply or anything? You could just hook up a push button switch as the flasher source and you just do the pushin on it to create the pulse the car would normally create, then use some 12v bulbs and your components and play with different combinations!

smitty2919

I don't actually. I found someone on CL with stock tail lights for sale that I asked about getting the wiring off of.

I just wanted to verify that my theory is correct. Playing with different combinations is not a big deal....the components are only a couple of doallrs each at RS. I will prob get another stock flasher as well to rip it apart and try to modify it...

I'll swing by the junkyard to see if I can luck out and actually find a mustang that is not picked bare lol.

devongarver

hmm well one thing I would be worried about is the discharge rate of the cap, and how long the bulb would stay lit after the power is taken away from the circuit. Jeez I feel like a tard because this is like 1st year stuff and I can't even remember it, I have to go look at my books this weekend...

smitty2919

From all the sites I have been on, the charging and discharging is not linear but exponential.

Here is a good site that I found for all and anything electronic. Scroll down on right hand side maybe 1/3 of the way to find the button for capacitors.

http://www.bcae1.com/

I thought about the discharge time as well. And from what I have found it's the same as the charge time...but I may be wrong. If that is the case...I wouldn't want my out bulb(at a 1.5 sec delay) takes 1.5 sec to shut off lol.

http://www.techitoutuk.com/knowledge...ors/capac.html

http://www.rwc.uc.edu/koehler/biophys/4g.html

I'm referring to the graphs that illustrate that. If this is true, then I think this is where the 555 timer would come in handy? It seems that the 555 will give me the allowed charge up time but a quick shut down time by by-passing the capacitor when cutting the flow to the bulb?