Aux rear LEDs - running + brake + turn?

[tom.gabriele]

My bike came with the Clear Alternatives integrated LED tail light, which I don't think is bright enough for braking and definitely not visible enough for turning. I also keep saddlebags on the bike 95% of the time, so I want to mount extra LEDs on the bags.

I plan to use the "Eagle Eye" style LEDs for this, because they seem to be bright and simple to mount. I bought these "9 watt" ones (which I measured to be 0.7 watts), but they are still surprisingly bright.

One thing I am not sure of is how to connect them. Since there is a different wire for brake light (yellow wire) and running light (blue wire), is it possible to use a single LED for both, or would I need some sort of relay for it? It would be ideal if it were just 5v for running, 12v for brake, but I don't think that's how it's set up.

Similarly for turn signal - I don't know whether I want to add a separate amber LED for turn, or use the same red LED as for running/brake. A separate LED would be simple (I already have an electronic flasher module), but is it possible to use the single LED for brake, running, and turn?

Thank you

 

[JHM]

I have an idea that might work for using a single led for your running/turn that will not require a relay, but will allow you to adjust how dim your running light is and run full bright for turn. Parts required should only be 2 diodes and a resistor.

You say you measured the operatimg power at 0.7 watts. Precisely what voltage and current was that at? I want to prototype the circuit at home and see if it works the way i think it will.

Jamie.

 

[tom.gabriele]

I used an AC power supply outputting 12.30 volts, with 55.9mA current. On the bike, the voltage will max out around 14.4v, right?

I came across these "Blinker Genie" devices that seem like they do the same as your idea...though I am confident parts for your design will cost less than $25.

Thanks in advance for the help!

 

[FinalImpact]

JM2C but if the Eagle come in red, I would dedicate that to run and brake as using amber for brake and turn (if I read that right), could misinform others especially if they only see the one side due to angle and saddle bag.

And the Eagle Eyes are cheap and very bright. Just a few more holes!!!

FWIW I made a switchback LED driver circuit that disables the DRL (on the front) and then reinstates DRL once turn indicator is canceled. It also flashes the pod light in sequence with turn indicator...

If you get creative, many things are possible!

 

[tom.gabriele]

JM2C but if the Eagle come in red, I would dedicate that to run and brake as using amber for brake and turn (if I read that right), could misinform others especially if they only see the one side due to angle and saddle bag.

I was thinking either:

1. Red Eagle Eyes for all three brake/turn/running
-or-
2. Red Eagle Eyes for running/brake, Amber for turn

But now I wonder if this would be better:

3. Red for brake only, Amber for running/turn

That would match the running/turn color and pattern as the front.

I agree that using amber for brake lights would be confusing to other drivers, which is the opposite of what I want to do!

 

[tom.gabriele]

I have an idea that might work for using a single led for your running/turn that will not require a relay, but will allow you to adjust how dim your running light is and run full bright for turn. Parts required should only be 2 diodes and a resistor.

You say you measured the operatimg power at 0.7 watts. Precisely what voltage and current was that at? I want to prototype the circuit at home and see if it works the way i think it will.

Jamie.

Looking for Blinker Genie alternatives that will do the 3-wire to 2-wire conversion, I came across these from Tripage (who seems to be an FZ-09 forum user), which seem to do what I want for just $5/pair.

 

[JHM]

I used an AC power supply outputting 12.30 volts, with 55.9mA current. On the bike, the voltage will max out around 14.4v, right?

I came across these "Blinker Genie" devices that seem like they do the same as your idea...though I am confident parts for your design will cost less than $25.

Thanks in advance for the help!

Ok, thats about what I fiigured, i will see if my idea works. Parts cost will be pretty mimimal, if you are lile me you should be able to scrounge up the necessary bits, the only question is the exact resistor value that will be required. Have to determime that experimentally, might try and find a suitable potentometer so that it can be adjusted at will, but a fixed resistor is cleaner and easier to waterproof.

 

[JHM]

Looking for Blinker Genie alternatives that will do the 3-wire to 2-wire conversion, I came across these from Tripage (who seems to be an FZ-09 forum user), which seem to do what I want for just $5/pair.

Might have a case of parallel ideas, I dont see a link, but the price range is about right for the components involved. Curious to see what other people have come up with.

 

[tom.gabriele]

Might have a case of parallel ideas, I dont see a link, but the price range is about right for the components involved. Curious to see what other people have come up with.

Whoops, I guess I didn't hyperlink the word "these" correctly. Here is the link: 3 wire to 2 wire signal converter

 

[JHM]

Tried out the idea seems to work well
All I am doing is mixing the two signals (running lights and turn) together with diodes, the running lights are routed through a resistor and diode to the led assy, and the turn signal bypasses the resistor through another diode.
I found that I needed a resistor value of 1000 Ohms to get the running lights mode in my experiment dim enough (5 mA current) turn signals are run at nearly max brightness (45mA in this case)


Increase the value of the resistor to make the running lights dimmer, opposite for brighter. Exact value will depend on the running current of the led lamp.
Ensure that diodes chosen will exceed the current requirements of the lamp. in this case 50 mA is well within the 1A limit of a 1N4007. Use a 1N5408 or similar if the temperature rise of the 1N4007 is more than you like.
Resistor should be 1/2 watt size, just to keep the surface temperature reasonable, it only dissipates about 60mW in my example.

This is, I believe, a minimum required parts solution to the single-led running light and turn signal.
One assembly will be required for each lamp.

 

[tom.gabriele]

This is, I believe, a minimum required parts solution to the single-led running light and turn signal.

Awesome, thank you! So let's see if I understand this correctly...in normal operation, the current from the running lights goes through the resistor then the LED, making it shine at partial brightness while the diode prevents that current from running backwards to the flasher module. When the turn signal is on, the diode allows the current to flow in the right direction to make the LED flash between *full brightness* and *partial brightness*. Is that accurate?

Does the voltage or current get added together when the turn signal is on, exceeding any tolerances of the LED i.e. am I sending full brightness the the LED from the signal circuit in addition to partial brightness from the running light circuit?

Also, would I need a diode to prevent 'backflow' to the running light circuit when the turn signal is on?

Lastly, how complex would it make it if I wanted a 50% brightness running light, but have it blink full-on and full-off when the turn signal is activated? That would require a relay in addition to the diodes?

I am very grateful for your help!

Edit: I just realized that I should check whether the bike turns off the running light when a blinker is activated. In that case, I will get the on-off blinking as well as the 50% running light without modifying your design. I can't recall what the bike does off the top of my head.

 

[FinalImpact]

Light Emitting Diodes operate from current and no the two signals do not add more tovether making more current when combined.

And no, you do not need another diode or relay. You just need to determine the LEDs current (it may be stamped on it) and reduce it by selecting the proper resistor. Because diodes have a saturation curve finding the edge where looks suitable in brightness may be a guessing game...

That said you may have to buy 10 sets of resistors two find two that work for your needs to offer the dimming effect you desire.

Digi-key and mouser are great sites for parts like these...

Follow these and it will get you started mind you you need 1/2 watt resistor, not 1/4...

1N4005 2@ $0.17 ea 1Amp 600v
1N4005 Fairchild/ON Semiconductor | Discrete Semiconductor Products | DigiKey

510ohm 1/4 watt
CFR-25JB-52-510R Yageo | Resistors | DigiKey

 

[tom.gabriele]

You just need to determine the LEDs current

As stated in response to JHM asking the same question, I measured about 56 mA @ 12.3 volts from an AC power adapter.

Based on that, JHM recommended a 1000 ohm, 1/2 watt resistor to reduce running to an appropriate brightness, with a 1N4007 or 1N5408 (for less heat) diode. Do those seem workable to you?

Also, do you recall the default behavior on the bike - does it shut off the running light when signaling? I can't picture what the fronts do off the top of my head.

Thank you

 

[FinalImpact]

Stock form they stay on always but are much dimmer than turn indicators.

Diodes = yes... good #'s. 4007 are cheap...
Resistor order many and just try them. Most are $0.10 or less if standard sizes are purchased.
Something like 2 sets of each:
1000, 910, 820, 750, 680, 560

And 4 sets of 100 ohm... resistors in series add.
So lets say 750 is too bright, add 100 ohm...
If 1000 is not enough, you can add to that to.
Don't forget 1/4 or maybe 3/8in shrink tubing!

 

[JHM]

You are all on the right track, you will have to play with the resistance to get the desired dim level. I do not have the same lamps you are using, so I tried to get as close as I could.
This is a simple solution, but has the limitation that it needs to be built specifically for your scenario and parts used.
Getting a selection of resistors is an excellent way to start working with this little circuit. the 1000 ohms is a starting point, based on my approximation of your specific example.

Keep in mind, I drew the lamp as a diode, but it is actually a diode with a resistor, the resistor is sized to limit the current to an appropriate level for the led that is used and 14V operation.
We are adding series resistance to further limit this current for the running lights, and bypassing it with the diode for the turn signals.
Two diodes are used to block current from flowing in unwanted directions.

I do not believe that the running light is turned off during signaling, and it does not matter, that is what the diodes are for.

another way to find your desired resistance would be to use a 2000 or 5000 ohm potentometer in place of the resistor so that you can adjust to the desired level, remove the pot from the circuit and measure the resulting resistance (I assume you have a multimeter) Choose the nearest standard value to make life easy.

And like Finalimpact says, don't forget the heat shrink.

 

[tom.gabriele]

You are all on the right track, you will have to play with the resistance to get the desired dim level. I do not have the same lamps you are using, so I tried to get as close as I could.
This is a simple solution, but has the limitation that it needs to be built specifically for your scenario and parts used.
Getting a selection of resistors is an excellent way to start working with this little circuit. the 1000 ohms is a starting point, based on my approximation of your specific example.

Okay understood, thank you.

Keep in mind, I drew the lamp as a diode, but it is actually a diode with a resistor, the resistor is sized to limit the current to an appropriate level for the led that is used and 14V operation.
We are adding series resistance to further limit this current for the running lights, and bypassing it with the diode for the turn signals.
Two diodes are used to block current from flowing in unwanted directions.

I now realize that I wasn't reading the diagram correctly. I should have googled the notation sooner. So I'll need a diode and a resistor on the running light leg, and a diode on the turn signal leg...anything else? What you say about the lamp as a diode plus resistor - meaning the LED itself acts as both, not that I need to add more diodes or resistors at that point, right?

Is there any downside to using a 5408 diode instead of 4007 besides price? The benefit is cooler operation because of the 3A capacity vs 1A on the 4007, right?

another way to find your desired resistance would be to use a 2000 or 5000 ohm potentiometer in place of the resistor so that you can adjust to the desired level, remove the pot from the circuit and measure the resulting resistance (I assume you have a multimeter) Choose the nearest standard value to make life easy.

Got it. Depending on pricing, I'll either buy a resistor assortment or a potentiometer first.

And like Finalimpact says, don't forget the heat shrink.

I have plenty of marine heatshrink kicking around, and I just ordered up some waterproof connectors for when I remove the bags.

Thank you all for the help.

On another note, I think I have decided to switch to using the red LEDs for running and brake, instead of the amber for running and turn - that should follow running light conventions better, and won't affect our little project here.

 

[JHM]

I can't do a partial quote from my phone, but in reference to the lamp.
Internally if you were to take it apart you should find that there is at least 1 Light Emitting Diode and at least 1 Resistor. This is so that we can simply connect the assembly to 14v and it will work properly.
If we connect a naked diode directly to 14v it will try to draw too much current due to its semiconductor nature, overheat, and burn out in a millesecond or less! So the assembly contains a resistor to limit the current.

Both 1n4007 and 1n5408 are a little overkill, the 5408 is a little more overkill is all. I was just trying to suggest common and inexpensive components.

 

[tom.gabriele]

Got it, thank you so much! I'll be ordering up pieces today, and I'll keep the thread updated with my progress.

 

[FinalImpact]

Also, you just need one pot like a 0 to 2500ohm (2.5k ohm or even a 0 to 5k)... if its rated at 1/4 watt that is fine for testing your LEDs.

You have an ohm meter? If not, then the potentiometer is of no help.

 

[tom.gabriele]

Also, you just need one pot like a 0 to 2500ohm (2.5k ohm or even a 0 to 5k)... if its rated at 1/4 watt that is fine for testing your LEDs.

You have an ohm meter? If not, then the potentiometer is of no help.

Yes, I have a multimeter.

Just ordered two 2k 1/2 watt potentiometers, which should (hopefully) give me all the range I'll need.

Thank you again.