Simple turn signals for a bicycle

If you commute regularly on your bicycle, the lack of sun in the winter can be a bit intimidating, particularly if your journey is not well lit. I ride my bike to work all year around, and in November, much of my commute is in the dark. I have a good set of lights (front and rear) to see where I'm going, but in the dark, people often don't notice hand signals. And of the folks that notice, many don't understand. I guess the left turn signal is pretty straight forward, but nobody really seems to get the right. And forget about stop and slow down... but I digress.

My goal is to create a very simple set of turn signals that anyone can build with a few basic tools. Where possible, I've used commercial, off-the-shelf parts, all of which should be available at your local bike shop, electronics shop, or online if you don't have access to these things in your town.

Disclaimer:
The recommended way to indicate turning is by using hand signals, and these shouldn't replace that. These are rear turn signals only. You still need to indicate you intention to turn to the people ahead of you.

Step 1: Required Parts

To build this, you will need the following (prices in Canadian Dollars):

Parts:
1- Two Rear flashing bike safety lights: $10.50 each
I used Blinky7 lights from Planet Bike. I got them from Mountain Equipment Co-op here in Canada. Probably REI in the US would have the same thing. Important: The lights must have a blinking mode, and the blinking must be sustained when the batteries are removed, and put back in. The lights I used have a capacitor that slowly discharges. This means that if I don't use my turn signals for 20 minutes, the light gets reset to a solid light and I have to press the switch on the light to set it back to blinking mode. Ideally, your light will have a switch that will remember the blinking setting indefinitely.

2- One AAA x2 battery holder : $1. Get one with a case to keep the batteries dry.

3- One Double Pole Double Throw (or DPDT On/Off/On for short) switch. $5.50
I picked up both of these items at Lee's Electronic - my goto shop for electronics in Vancouver. Probably Radio Shack would have something similar. My battery case has an on/off switch, but that's not really required, as the switch will be used to turn them off. If you can find a waterproof switch, that would be ideal.

4- Wire. Red and Black. 6 feet of each should do, or enough to go from your handlebars to the just at the top of the seat stays and back. 26 gage or so should be fine, but anything reasonable will work.

5- one extra long screw that will fit the nut of the Blinky mounting setup.

Tools:

6- a little silicon , similar to the stuff that you would use to seal around your bathtub.  Caulking, Shoe Goo, or Goop will also work.

7- A little strip of adhesive Velcro (both sides)

8- Solder and a solder iron. Or you could use silver conductive epoxy if you don't have access to a soldering iron.

9- Xacto knife

A set of helping hands (the mechanical device, not another person), and a set of wire cutters were also used, but you could get by without them.

Comments

[nilliks]

I tried building this using your design but there was a problem. The light has a flashing and steady mode. I pushed the switch till it was in flashing mode but it looks like once you kill power, The circuit board resets and it goes back to off. Its weird because if you kill the power to it and turn it back on again within 5-10 sec, it still blinks; however, if you leave it off for any longer, it resets to off. Damn, I built the whole thing, now it doesn't work. :( Any ideas?

[NEIN]

Interesting... What type of light did you use? Let me see if I can find a solution. Do you have access to a soldering iron if it comes to that?

[jarvallmighty]

I tried this years ago but never sorted out all the bugs. Hope this helps with anyone that wishes to do this cool project. You can usually find the "cheapo" amber jogging lights in a dollar/discount store but search in the pet/sports/toys dept. Might have to hunt but they're out there. If you use electrical tape you can mask off an arrow and use very fine sandpaper too scuff the lens. Just enought to take off the shine and then use a sharpie marker to color it in, tada, arrows. Some of these cheap lights have solid/flash/rapid flash options so if you can find a flash only light you only need to short the button switch on the back of the lights to your DP/DTswitch. The batteries are self contained in the light so you don't need a battery pack. You could have a feedback circuit for a left/right LED so you know it's on and all you need to do is hit the switch again and it will turn off. Add a generater and an electronic voltage regulator and you could recharge the batteries on the fly.

[gary art studio]

for everyone who yellow light?
look up Part s for scooter
than hit lites and you will find all the lites you want

[JohnMichael]

The thing I would suggest as wanting change the most is that turn signals are amber/yellow, not red. Drivers may not recognize a flashing red light as a turn signal.

[heathbar64]

ok, here's a challenge for y'all. make the switch self cancelling like they are on a car. especially since you can't hear the flasher to remind you.

[NEIN]

I have to say this has been on my mind since I first created this. Two options come to mind, though neither of them are perfect:

1) Put the turn signals on a timer so they would shut off automatically after an extended period of time. Not ideal really.

2) Some sort of beeping, or flashing LEDs near the switch to let you know they're still on. I think I like this a bit better.

Does anyone else have any ideas? I guess if it was that easy, motorbikes would have signals that shut off too.

[neojep]

i have a "on/off/on" momentary switch at home. i dont know mutch about electronics, but i think that would work just as well, and that would, if placed apropriatly, alow you to hold it in the right direction while you turn, and then you just let go when you finish turning and it shuts off. what do you think?

[Advar]

Great idea!
I pretty much did what you did, only twice the lights and batteries, and clip on safety flashers that I could only find with transparent cover, so I replaced the white leds with amber. Probably could've used orange cellephane behind the lens instead though.

[NEIN]

Very cool! Do you have any pics? The amber colour is quite important I think. It's too easy to mistake the red lights for regular bike flashers. What lights did you use? If the lens comes off, perhaps you could make an arrow shape with electrical tape on the inside?

[Advar]

The lights I found in a dollar store were called Safe-T Blinks or something, about the size of a penny, pack of two.
Wish I could show pics, but I' m restricted to library computers :(
Like the arrow idea.

[pilooZ]

Very nice idea.
Why didn't you use the bike itself to pass the ground signal ? Is it possible ?

[NEIN]

I guess it would depend what material your bike is made out of?

[moorea7]

Of course, you could always build yourself a flasher unit and use regular lights? I remember building such a thing with my Radio Shack electronics kit (think spring terminals and components mounted in a cardboard and plastic frame!) so could be built with a few resistors, capacitors transistors and relay.

[NEIN]

Thanks Moorea7, I think I might consider this for a future version, particularly if I can keep it simple and cheap.

[jeffeb3]

Look up circuits for 555 timers. They have 2 settings: cycle rate, and duty cycle. You could have a switch that dramatically switches the cycle rate, from 0.5Hz to 1000Hz, and the light would switch between a dim (50% max) constant light (1000Hz) and a bright (100% max) blinking light. There are a lot of circuits on the web. I think you would have to have a second capacitor in parallel with the first, and use a switch to connect or disconnect it.

At any rate, there's no reason why you have to depend on the commercial blinking component. They probably have a 555 timer inside you can just disconnect and use.

I think the solid, dim left light and the blinking bright right light would indicate a turn much better than just one blinking light that might be on either side of the bike.

[NEIN]

Thanks Jeffeb3. I've used the 555s a bit for music, but that's a great idea. I think for the next version, it's critical to:

1) have the lights on solid (even dim) when they are not flashing

2) use orange lights. Here in Canada both red and orange are used to indicate turns, but I think orange on a bike would be a little more clear.

3) Have the flashing light in some arrow shape.

My plan for this is to design something in Sketchup that will mount to a bike frame, allow any off the shelf light to clip into it, and have some arrow shaped cut out in the back so the light appears arrow shaped. Then I'll print it on the Makerbot and upload the file to thingiverse.com so people can print their own.

I'll call it 'Difficult (but effective) turn signals for the bike ;)

I'll definitely check out the 555s

[susanrm]

Great idea. Around here, though, the right hand signal is sticking your right hand out. Nobody uses the bent left hand anymore, because as you say, nobody understands it. Maybe a pair of light-up gloves could accomplish the same task too, and the switch could be easier to press inside the gloves.

[jeffeb3]

I thought I saw an instructable building the lights into a jacket. Big arrows. Seemed like a good idea if you alwasy wanted a jacket (and you knew you were leaving after dark).

[Musicman41]

Not entirely true. In Seattle, people generally understand the upward bent left arm to be the right hand turn signal.

[susanrm]

Maybe so, but there's a difference between "generally" and "everyone," and if you travel with a bike, then you have to deal with other situations.

[ferservadu]

Cyclists may not generally use the bent left arm, but motorcyclists and scooter riders do, since you need to keep your right hand on the throttle. (Denver actually recently passed a law legalizing the right-hand signal for cyclists. I don't think anyone realized it wasn't legal until that point.)

[sandraellis]

Very nifty. I like anything that makes riding a bike safer

[wobbler]

Good idea, but I'd suggest you get two amber flashing lights instead of red ones as this is the common colour for a turn signal. You can buy cheap amber flashing lights or replace the red leds with amber ones if you're desperate.
Also, some lights will automatically go into flashing mode when batteries are inserted, or if the switch is held down and batteries inserted. If it's the kind that needs the switch held down, just take apart the light and solder over the switch contacts so the light will go into flashing mode automatically whenever the power is applied.
Using amber lights with a central red light would also distinguish them as turn signals.
The only real problem I can see is that drivers aren't used to seeing turn indicators on pushbikes and might just assume that you are being extra careful in being seen. To be honest, I wouldn't rely just on these when changing lanes or turning. drivers are blind enough to cycles as it is, but they should help to reinforce the turn hand signal.
As an aside, I found the upward bent left arm signal interesting, but don't try it in the UK, they'll just assume you're waving at them or pretending to be Hitler on a bike.

[gear head]

Ahh, this is where we get regional variation. I believe in the UK it has to be an amber turn signal whereas in the US running lights and turn signals can both be red. I've seen night lights for walkers and joggers that were red LED's with a clear lens cover... maybe you could accomplish both colors in one housing by swapping out a couple of the LEDS? Either way, I'm all about road safety and think this project is not only very cool, but possibly marketable also.

[NEIN]

Hi Wobbler,

Yes, amber lights would be better. I've added that under the future enhancements section. I'm curious how people indicate a right turn in the UK? Is it the 'right hand out' method?

[wobbler]

Interesting about the red indicators. Right hand out, yes, for both bikes and motorbikes although with proper indicators motorcyclists no longer using hand signals.

I also remember signalling using the right hand out, and moved up and down to show you were slowing down or pulling into the kerb when stopping on a motorbike.

I could also mention a few non-Highway Code signals I used when I was cut up by cars, but I think they are mostly international and well known and occasionally still come in useful.

[gear head]

As a motorist, I'm more likely to recognize a turn signal if it flashes at the same (or similar) rate to most vehicle signals. Taking your idea a little further, and for safety sake might I suggest that both lamps be constantly illuminated at a lower brightness and then when the turn signal switch is thrown they flash more brightly? At a distance it might hard to discern that the flashing lights are not just the usual rearward facing lamp since there isn't much separating them.

[NEIN]

Great idea! This would solve the problem of having no light on when you're not turning. This instructable has generated a lot of interesting discussion with regards to how bikes are viewed. I might incorporate a set of 3D printed arrows that the lights can just clip into for the next version.

[neonindigo]

(removed by author or community request)

[NEIN]

What an interesting design! I considered a wireless version, but I thought the extra cost, power consumption, and complexity would outweigh the benefits.

[Johenix]

An arrow from 8 LEDs: Take a small round plastic box (snuff box size) and make 8 holes in it in a square, like a baseball diamond, one each for first, second, and third bases and home plate, and four holes on the base paths.
Wire the diodes like this: Left turn: Power flows through third base diode, then in paralell through the two base path diodes to the second base diode to ground (and the home plate diode to ground). Right turn: Power flows through first base diode then in paralell through the other two base path diodes to the second base and home plate diodes.

You can expand the arrow to 12 LEDs by putting two (or more) diodes in series on each base path. Use dimmer diodes for first and third base since the other diodes will only get one half current.

Total voltage drop red LEDs: 3 diodes= 5.55v, 4 diodes= 7.40v, 5 diodes= 9.25v