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Motorcycle Flasher Issue

Mongrel Shark

Jun 6, 2012
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Boost converter to battery via diodes would be my tip. The magneto is likely giving neg spike's... that's causing the flicker. I bet the flicker changes speed with revs...

Definitely try going as close to battery as possible. Like Chris say's it is a good regulator. A pair of diodes one out from pos and one in to neg could help a lot too.

I've been thinking about this too. Would be great to be able to do. If you can get power tho the boost chip, the rest should work. I'd say the magneto is switching your chip on and off really fast, causing the flicker... Been a long time since I played with magnetos though, and my electrical knowledge was not as good then.
 

KrisBlueNZ

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Have you tried just putting a diode in the supply line to the 555? Where Chris suggested inserting a 10 ohm resistor (between the light bulb and the 555 pins 4 and 8), add a diode in series with that resistor, and put at least 100 uF smoothing across the 555. Another straw to grasp at!
 

gturbo7

Oct 27, 2012
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I just connected the boost converter directly to the battery through diodes like you said, no change, still flickering. Do you see any problem with my two relay idea?
 

gturbo7

Oct 27, 2012
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Here is a diagram of what I am thinking about. The relays would be automotive style with a N.C. and a N.O. output on each. I couldn't get it to work in the simulation of multisim but I'm not seeing how it would have a problem in the real world. The resistors are just in there because I was trying to mess with it to make it simulate. The leads going off to the right are going to the scope. https://docs.google.com/open?id=0B2gBjUuRY9-PeVYyZ1VHV25adnM
 

KrisBlueNZ

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I've had a quick look through this thread. I may have missed something, but it seems like you already have a 6V battery on your bike. So the only reason you're using a 6V-to-12V converter is because your flasher needs 12V. Right?

You can easily run the 555-based flasher circuit at 6V. Then it's only the high-power LEDs that need the extra voltage, right? I think your best bet is to run the flashers at 6V from the main battery that's already present.

Can you open the indicators and find out what's inside? It should be pretty easy to re-wire the LEDs so they'll run at 6V, and you already have the 555-based flasher circuit (though as CDRIVE suggested, you should use a power MOSFET to switch the load instead of a 2N3055!)

The flasher circuit still needs the usual automotive protection stuff - smoothing capacitor(s), series resistor(s) in the supply, and perhaps a varistor or other type of surge suppressor.

Another thing to try. You say the flickering only happens when the motor is running, and you think it's due to the magneto. It could equally be due to the ignition system (someone else already suggested this). Can you temporarily disconnect the magneto, or temporarily move it so it doesn't turn? That will tell you what is causing the flickering.

Edit: Here's a suitable MOSFET - the NTD3055L. Its ratings are more than you need, but it's cheap.
http://www.digikey.com/product-detail/en/NTD3055L104-1G/NTD3055L104-1GOS-ND/1484764
 
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Mongrel Shark

Jun 6, 2012
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Re two relays, Only problems I can see, is they might be a bit power hungry, afecting charge rate. And you might need headlights brake light etc to still work when indicating...

Have you checked to see if relays work with magneto? You might have the same issue? If so perhaps you could add a cap and make the relays do the flashing? Like a flasher cam.

I think my old XT 500 used to have a magneto, and blinkers. As did my TS185. The XT had flasher cams, like in a car, attached to the regulator. I think. Pretty sure the ts was the same. If I blew a globe, or changed the wattage, the flash speed would change. I know the TT (enduro version of the XT) had big issues if you wanted blinkers. The most common approach was to put an XT loom in... Even then I don't think it would do headlights and blinkers well. Due to the magneto being so small and light. The headlight would dim to almost nothing when the blinkers illuminate. They tend to barley make enough power to keep battery charged. Adding extra load can cause all sorts of issue. I'm still leaning towards 4xAAA and 6v led flasher. If you have room for 2 relays, and a step up board, you have room for 4 AAA's and a two transistor flasher... I know technically they should flash front and back in sync, but lets face it, what we are discussing is not going to be road legal anyhow, I am assuming it's for farm safety or some such, so having them flash front then back could be ok? Being an enduro, there should be storage for tools. Or you might be able to hide stuff in the airbox, or under the tank, attached to the frame, or sub frame. Under the seat, on the headlight mount, on or inside handlebars, even hollow out a bit of seat and put in there... Use your imagination.

If you tell us what model bike it is I will see if I can find more info...
 

Mongrel Shark

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Kris. I like all of those last suggestions. I have been thinking 12v led complicate things way to much also. Disconnecting the magneto is a great suggestion. I'm pretty sure that's the Issue, as I have come up against it before. As have most of my bike mechanical instructors. It's a real demon of the dirtbike world... would be good to confirm its not the spark though, if its the spark that changes things a lot...
 

gturbo7

Oct 27, 2012
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The bike is a kawasaki f7 1971. The leds are a glued plastic housing with no fasteners and I'm pretty sure they have current limiting resistors because I played with them with a power supply and the current wasn't climbing like an led normally would.. they need 12 volts, that is the reason for the boost converter, I couldn't find prefabbed 6v leds for a bike so I went with these. I thought the relays would work because when I flick the mechanical switch it would separate both terminals of the battery from the bike completely and just drive the flasher circuit until I hit the switch again, unless I'm overlooking something..
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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No, I don't think you're overlooking anything. It just seems like such a back door approach to solving this. Before you go through all that rewiring it might be advisable to test power the circuit from a separate 6V battery or wall wart. If the problem persists it's most likely spark noise causing this.

Here's another thought.. Have you tried disconnecting the magneto rectifier diode from the battery? I don't know if this could hurt the magneto, so you may want to think about loading the rectifier output with a lamp if you test this.

Oh, how I wish you had a scope.

Chris
 

CocaCola

Apr 7, 2012
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I personally like the relay flip flop relay idea, when you activate the flash it disconnects the magneto from the battery... A crude work around but it pretty fool proof...
 

CDRIVE

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I personally like the relay flip flop relay idea, when you activate the flash it disconnects the magneto from the battery... A crude work around but it pretty fool proof...

In that case, wouldn't it be advisable to simply disconnect it for a go- no go test before wiring in relays? If it works, great, but if it doesn't he'll save a lot of effort.

Chris
 

CocaCola

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In that case, wouldn't it be advisable to simply disconnect it for a go- no go test before wiring in relays? If it works, great, but if it doesn't he'll save a lot of effort.

Of course, I can't see it not working though unless there is something seriously wrong with the circuit, and at that point you have other issues to contend with...
 

gturbo7

Oct 27, 2012
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I have tried disconnecting the rectifier diode, didn't change anything. I wish I had a scope too. I have not tried running the turn signal circuit with the battery disconnected from the rest of the bike yet, I will try that.
 

gturbo7

Oct 27, 2012
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Well I guess its a good thing I did that test. The flickering continues even with the entire bike circuit disconnected from the battery. :-(
 

gturbo7

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So I guess this means it is spark noise? Would shielded wires help possibly?
 

CDRIVE

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Well I guess its a good thing I did that test. The flickering continues even with the entire bike circuit disconnected from the battery. :-(

The guilty party is looking more like spark noise. Please post some good photos of the board itself, component and solder side. Photos of the unit while on the bike might be useful too. You may want to start thinking about ferrite clams too.,,More straws to grab at!

Chris
 

gturbo7

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The flasher board is in a plastic project box from radioshack. The converter is in a plastic ear plug container as a temporary container until i found out if I could make this thing work or not. The battery is under the seat, so when I have been running the bike, I leave the seat flipped up and these two containers are just sitting right there close to the battery. The turn signal switch is mounted on the left handlebar. It has a metal housing that the headlight switch is mounted inside too.(possible noise transfer spot?)
 

CDRIVE

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So I guess this means it is spark noise? Would shielded wires help possibly?

They won't hurt. Don't know if they're still available but ignition and alternator noise suppression kits were once available. I think the spark plug wires were resistive. They were popular with hams.

Chris
 

CDRIVE

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