Sequential LED's (like the New Mustang's Turn Signals)

[Falcon69]

My nephew redid his truck, turning it into a flat bed.  He bought 6 LED lights, 3 on each side. He has asked me to make a circuit so he can have the lights flash in sequence like they do on the new mustangs when he turns his turn signals on.

Now, I've checked at the circuit box, pulled the flasher module, and jumpered it.  By doing that, it no longer flashes, but stays at a steady light when turn signals are on. So, there is a continuous supply of 12 volts going to the back of the truck to the lights via the factory wire harness.

I tried looking on google for a circuit that will work, but when i try to run a simulation, it doesn't seem to operate with transsistor/mosfets, resistors, and capacitors.

Some other images show using a 555 timer and a 4017.  what is a 4017? A decade counter?  Will that work? I am guessing that the outputs of the decade counter must be used with mosfets or transistors, as his LED lights probably draw too much power for the decade counter. My simulation program I am using does have a 555 timer circuit in it, and a decade counter circuit, but I'm not sure how to draw it up using those just yet.

Anyone have a simple circuit that will work for this application?  He wants them like this


Thanks in advance,
Jason

[theatrus]

What circuits have you tried, and what's your experience level?

If this were me, I would simply take the lowliest MCU I had sitting around to run the logic, and use three big enough FETs (or even relays for an authentic auditory experience) to drive the bulbs.

[Falcon69]

I found this

http://homemadecircuitsandschematics.blogspot.com/2011/12/how-to-make-car-led-chasing-tail-light.html

but, i'm not sure how to make it work with these

http://www.ebay.com/itm/2-Trailer-Truck-RED-LED-Surface-Mount-6-Oval-Stop-Turn-Tail-Light-Sealed-/160975575861?pt=Motors_RV_Trailer_Camper_Parts_Accessories&hash=item257ae45b35&vxp=mtr

Those are the lights he bought. 3 for each side.

[jlmoon]

www.engineeringshock.com is one of many places you can find a sequencer,  all you need to add would be some mos or hexfets to handle the power demand of those LED assemblies such as IRF44ZN on a small heatsink and your good to go.  Only reason I suggest this part is because I have shelf full of them.  You will need to allow for latching all outputs high when brake signal is present, in other words pull the three gates high (both sides) when brake signal wire is active and no signal light active.     Hope this makes some sense to you

[Falcon69]

what I dont understand is the 4017 has 10 outputs.  Do all the outputs need to be used?  Can i just use 3 of them, and hook them to a mosfet which controls the LED?

[jlmoon]

Since you're only using 3 led assemblies per side, you would only use output 0,1 & 2.  Two circuits required one for left and one for right.. unless your into some serious driver (mosfet) switching to drive each side with one sequencer.  Could be done tho, such as if a manufacturer were building millions of these.. then the cost savings would be quite significant.  One clock, one 4017 with some  enable gating logic (OR gates) and a mosfet for each lamp would do the trick.

[Falcon69]

that link i posted from homemadecircuits has one circuit to operate it both sides.

So, if the other pins of the 4017 are not connected, they are just ignored in the count?

[jlmoon]

yes.. or you could gate them if you don't desire the delay time between clock cycles from 3 - 9
0
    1
        2
             3(wait)
                 4(wait)
                    ....
                       9.. wrap around
0
see the idea?

[Falcon69]

oh, okay, so there would be a delay while it counted through the other 7 outputs.

What do you mean by gate?

Use an or/xor gate on the unused outputs and tie them to outputs Q0 (pin3), Q1 (pin2), Q2 (pin4) that will be working with the LED's?

[jlmoon]

Yes, using OR gates you can put 3 with 0, 4 with 1, and 5 with 2, as well 6 with 0, 7 with 1 and 8 with 2.. then let it rest for 9.  Best way to do this is breadboard it using actual leds or small bulbs with the actual mosfets and watch what happens.
Keep in mind you have to deal with the brake light scenario as well.  When the brakes are applied along with say the left turn signal .. you need to still have the left turn sequence working but the brake signal muted only to that side or the Brake light will mask the effect of your sequencer. Does this make sense?

[jlmoon]

IIRC, when using the brake with turn signal.. I think the brake 12v is applied to the signal flasher (for the turning side) and then routed to the bulbs on the turning side.  For this to work correctly you will need to remove the flasher and handle all this with gate logic.  Typically with OR logic routed to the gates on your mosfets, great thing about the parts you're using.. they will handle 12 nicely.  Just as a preventative measure be sure to put some over voltage protection/regulation on the supply to those ic's.  They can't handle much above 18volts, bad battery, jumping cars off can get a bit extreme on a cmos part. 

[Falcon69]

Yes,

I will work on drawing up the circuit now.

I will need to apply some kind of a mosfet/transistor switching so that when the turn signals are on, the running light is not on, meaning, the lights are are always dimmed to show the vehicle is on, so I will want that to switch off when the turn signals are working.

[Falcon69]

I will have to check his vehicle, but I believe there are 3 wires, Ground, Brake, and Turn Signal.

I took off the flasher module from his circuit board on the car, and jumpered it. It supplies a continuous 12volts to the rear lights (left or right) when a turn signal is activated.

There might even be a fourth wire for running light, for when the lights are turned on, if that is the case, should be easy to make it so the running lights turn off when the turn signals are activated.

[jlmoon]

Since you're in the U.S. as I am, the running lights are on an entirely different circuit.  I don't think the running light power is interrupted when turn signals are on.  Not on a late model car anyway
I presume you could sink a running lamp filament and control as you please as with any other lamp, but not sure you want to go through all that.

[Falcon69]

ya, I would just think it would look better if none of the LED's were dimmed during the turn signal operation. I might not look right when some are dim, while others are bright. 

[Falcon69]

I have a couple 7805's here, but I'm fairly a newb when it comes to electronics. Microcontrollers are out of my scope of knowledge.

Do you have a schematic of what you are talking about?

[jlmoon]

oh good point.. I'm still on the track of two different led board assemblies in the module..

I will have to check his vehicle, but I believe there are 3 wires, Ground, Brake, and Turn Signal.

I took off the flasher module from his circuit board on the car, and jumpered it. It supplies a continuous 12volts to the rear lights (left or right) when a turn signal is activated.

There might even be a fourth wire for running light, for when the lights are turned on, if that is the case, should be easy to make it so the running lights turn off when the turn signals are activated.

Think of the wiring in the concept of a trailer.. usually one ground lol.. sometimes (black) , clearance or running (brown), left turn/brake (green or yellow can't remember) and right turn/brake (green or yellow opposite of other side)
now that's a 4 wire plug
the 7 or 8 wire systems just add some extra stuff for electric brakes, charge wire for battery.. etc

[jlmoon]

A $5 microcontroller and six cheapass relays would work splendidly. All else you'd need would be a 7805 or something.

I like the microcontroller concept as well, provided one has the IDE to code the part.  lol.. then he could put a lcd display on the dash with a key pad and have a very dynamic sequencer.. 

[jlmoon]

You only need, what, six outputs and three inputs, right? So an ATTiny84 would work just fine. Literally $3, and you only need one.

For switching, these $2 relays should work. Oh, and add a bypass cap for good measure.

don't forget about the transient protection for both the controller and it's outputs?

[jlmoon]

coil current requirement for that relay.. @ 37.5mA.. pushing the limit on that ATTiny84 part.. only good for 40mA.. max.. .. for design reliability.. better do some buffering between them.

[Falcon69]

that gets too complicated for me.  I don't have the equipment to program the chips.

Those lights draw more then 40mA.

[jlmoon]

"That's why there's a relay. To program the chips you need a $10 arduino. "
yes.. but the relay is drawing 37.5 mA.. and that poor chip can only do 40mA maximum ratings.. thats pushing the envelope more than I would
as the device was designed they didn't intend on you loading it at over maybe 60% of it's rated output (generalizing of course).  I sure wouldn't if I desired reliability.

so do the LED assemblies have two or three wires per?

[Falcon69]

3 wires coming out of the led assemblies, GRN, Brake, and Turn

[jlmoon]

3 wires coming out of the led assemblies, GRN, Brake, and Turn

so... there's your answer.
the running lamps have their own board, so it is up to you if you want to mute the running light LED while in turn mode.  Add one more mosfet to the pot of parts for each side
then suppress the gate drive to that part when you're in turn mode.. so you don't see the dimmed LED, thinking you will need a XOR for that one.. wow.. going back to my karnaugh maps
.. I would need to do the logical operators on that one

[jlmoon]

all for L or R side:

Brake  & Running = Running Enable (1)
No Brake & Running = Running Enable (1)
No Brake & Turn Enable & Running Enable = Running Enable (0)
Brake & Turn & Running = Running Enable (0)
and it continues.....


now draw the schematic..