Heres a short demo of it. Its just wired to a battery so it doesnt turn on and off by itself. You can see the sequencing works but the delay is a bit too slow
Also attaching a pic so you can see how simple the design is.
http://www.youtube.com/watch?v=iZf8DhPqlas

 

Is there a way to increase the speed of your lights in your test model? They seem to come on rather slow
Or would you have to get a different IC?

 

The timing is changed by changing out the resistors or capacitors, i have other resistors i just havent had a chance to find the exact timing needed and then do the math

 

I havent studied electronics in so long, hell, I have fogotten what the base dimensional units are for ohms and farads. If I remember the base dimensional units, I could do the dimensional analysis to do the calculations myself to alter the timing, LOL

For some reason, I was thinking the timing would be set up by a crystal or a setup of capacitors and inductors, which I though would be fxced in the IC.

 

Gradumated EE here. So I supposedly know something or the other about this stuff. Don't have time right now, but I'll definitely try to take a detailed look at this stuff sometime this weekend.

 

Yea, I did the logic with a PIC.
555s (556s)are not stable enough
for the wide temp swings of the
auto enviroment. And are very old school.
A better bet would be 4000 series CMOS
and a counter/divider arrangment.

But why when PICs abound and kick ****.
And they can be made to be self calibrating
as to the timing of the lights per actual vehicle.
Unlike the Meter4It kit that requires you to
initially set up the timing.

We have come a long way since 555s.
And you really want DEPENDABLE rear
brake lights and turn signals, dont you?
Save a buck somewhere else and get
the good stuff for what really counts.

The better question is did anyone try and
reinvent the wheel just for kicks?

 

What problems do you think i will have running a simple circuit with 555/556s?
I had a few people recommend using micro-controllers but i have no clue how they work and the 555 circuit is extremely simple.

also does anyone have a schematic of the wiring for the tail lights? Is there just a power and ground running to each or how is it setup? Im still trying to figure out how to implement the circuit but i have some pretty good ideas i just need to know the current wiring (and if my circuit will even work?!)

wasnt able to find a consistent answer but when i googled operating temperatures i got something along the lines of
Min Operating Temp 32 F
Max Operating Temp 158 F

 

Operating temperature wise, if you select the right chip, none. 555s are available all the way from basic to military grades. It's not hard to find one that can handle the temperature.

A microcontroller (PIC) is a chip controlled by a (usually) simple program. Take a look at howstuffworks.com to get a general idea of how one works.While it would probably be the easiest way to do it, it's also probably a bit over kill. Also, unless you're able to borrow/use something from your school, you'll have to buy some form of a starter kit. Unless you're wanting to make a kit to sell, that goes against the whole principle of keeping this thing cheap.

I'm assuming this is for your 555 chip. You'll probably need a chip that can operate below freezing. Finding chips that can operate at a high enough temperature will be easy enough. It's the ones that operate at lower temperatures that are somewhat more difficult, though certainly not hard.

 

The SE555 has an operating temperature range of -55°C - 125°C

http://www.unitechelectronics.com/NE-555.htm

I'd personally feel a microcontroller would be overkill for this application. You can get a SE555P for $0.75 and it has the same temp range.

http://www.ibsstore.com/scripts/prod...idproduct=3253

 

I currently have NE555 which run from 0 to 70 C so i would probably need to find/order some with a better temp rating but these will work for a prototype just fine.

While i microcontroller would work i really dont see why the 555 is such a bad idea. It seems super simple in theory but i could be wrong. All i way to decrease the current to the 555 (voltage regulator?? im still using batteries so i havent looked into that) a small cap, resistor, and a relay to send the power to the lights. I dont plan on touching the inner lights wiring at all and i could just make two small chips that i splice into the power wires to the lights and both powers the IC and relay.

For now im just enjoying the learning experience in circuit design and PCB prototyping. I picked up some copper clad board and etchant some hopefully sometime in the next week I can make a test PCB just using the leds and batteries. Mainly to learn the etching process. After that ill start figuring out how to regulate the current going to the chip and setting up a relay for the lights.

I still need to get the timing down a bit better but i have no way of measuring the tail light cycles as of now so im just making guesses for now.

Hopefully ill have some updates soon but ive spent most of the weekend reading up on pcb design and all sorts of other related topics and no time actually studying for school. I dont plan on actually installing any prototypes till spring break (3-4 weeks i think)