Hello! I'm interested in adding a 'chaser' function to the taillights on my car, which has three 12v bulbs on each side. I've seen plenty of DIY kits, but I'd rather not pay $80 or more when I can solder up two simple boards. I cannot for the life of me figure out how to make a simple delay circuit using transistors, and most circuits I've seen are based around timers or counters. I'm looking for a simple circuit that uses transistors and capacitors to make three 12v bulbs light in sequence. I can adjust capacitor values later to make the sequence fit between blinker pulses.
Easier to just use a tiny85 to do it imo - then instead of caps, you just have 3 transistors for the LEDs, and wires going back to the 85 (including one to get it to synchronize with blinker pulses).
Be sure that what you are doing to your lighting does not violate traffic laws.
It shouldn't be illegal, the same design is in place on most modern Mustangs.
And how would I go about programming something like that?
//presetup definitions and
// void setup() coding left as exercise to the reader ...
// now the interesting part
void loop(){
if (triggerSignalLeft == LOW){
digitalWrite (left1, HIGH);
delay (500);// "dumb" delay for on-time
digitalWrite (left1, LOW);
delay(100); // brief pause before next light
digitalWrite (left2, HIGH);
delay (500);
digitalWrite (left2, LOW);
delay(100);
digitalWrite (left3, HIGH);
delay (500);
digitalWrite (left3, LOW);
delay(100);
}
if (triggerSignalRight == LOW){
digitalWrite (Right1, HIGH);
delay (500);
digitalWrite (Right1, LOW);
delay(100);
digitalWrite (Right2, HIGH);
delay (500);
digitalWrite (Right2, LOW);
delay(100);
digitalWrite (Right3, HIGH);
delay (500);
digitalWrite (Right3, LOW);
delay(100);
}
and get fancier from there - # of times to go thru each sequence, stopping a sequence early to move to other light, allow both to flash, etc.
That is definitely very helpful, but I still have no idea how to actually get the program onto the ATTiny.
I've not used the smaller, lower capability chips myself.
There are some simple changes to add them as a board type in the IDE, then you can bootload and program like any other board.
I cannot for the life of me figure out how to make a simple delay circuit using transistors, and most circuits I've seen are based around timers or counters. I'm looking for a simple circuit that uses transistors and capacitors to make three 12v bulbs light in sequence.
A couple-million years ago I built a car alarm with R-C timers. With a big capacitor and and a high-value capacitor I could get exit & entry delays of several seconds. (IIRC - I took the "analog approach" because noise in the 12V power was causing havoc when I used a 555 timer.) But, you can't run the R-C charge-voltage directly into a MOSFET or transistor because the MOSFET/transistor needs to "snap-on" or "snap-off". (If it's half-on it will overheat). And, the resistance in an R-C circuit means you can't directly power a relay coil.
And how would I go about programming something like that?
If you can [u]blink one LED[/u] you can blink/sequence a few more. The hardest part would be wiring-up MOSFETs and/or relays to the light bulbs.
The trade-off with using a microcontroller as opposed to a 555 timer and flip-flops is cost. It's easier to do in software, but it costs more.