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Dynamo f/r set up: rear light never turns off

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Dynamo f/r set up: rear light never turns off

Old 10-07-23, 06:08 AM
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Dynamo f/r set up: rear light never turns off

Hello!

so I have a shimano hub dynamo that goes to a front light with a switch. And then an output cable from the front light goes to the rear light.

Everything works fine, but as soon as I flip the switch on the front lamp off, only the front light turns off and the rear one continues working.

Is this a common thing?
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Old 10-07-23, 10:03 AM
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Some taillight's have capacitor backup. The capacitor stores a few minutes of power so you are visible to traffic when you are stopped. This is called a stand light. If this is not your problem then give more info about your lights.
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Old 10-08-23, 05:47 AM
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Originally Posted by Rick
Some taillight's have capacitor backup. The capacitor stores a few minutes of power so you are visible to traffic when you are stopped. This is called a stand light. If this is not your problem then give more info about your lights.
So hereís the set up:

Dynamo: Shimano DH-3N72

Front lamp: Hosim (https://www.amazon.co.uk/Hosim-headl.../dp/B08H8BV7HB)

Rear lamp: Supernova E3


I donít think itís an issue with the capacitor because when I push it from a cold start (as in I take it out of the garage), the rear light will blink when spinning and turn completely off when stopped. I canít turn it off with the switch on the front light.
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Old 10-08-23, 07:50 AM
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Is this your first time using dynamo lights?

This is normal in every dymano light in the world. The taillight stays on for several minutes after you stop.

The purpose of this design is so you do not get killed by a car when you are waiting at the intersection.

Some taillights have a switch to turn off. Your light does not have this feature, so you will have to wait several minutes for the capacitor to run out of power.

There is nothing you can do.
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Old 10-08-23, 08:40 AM
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Originally Posted by Yan
Is this your first time using dynamo lights?

This is normal in every dymano light in the world. The taillight stays on for several minutes after you stop.

The purpose of this design is so you do not get killed by a car when you are waiting at the intersection.

Some taillights have a switch to turn off. Your light does not have this feature, so you will have to wait several minutes for the capacitor to run out of power.

There is nothing you can do.
I know exactly what youíre describing, because Iíve used bikes that do exactly that. Mine does not.

When the front wheel moves slowly, both the front and rear strobe on and off. The faster you go, the more the strobbing disappears. As soon as you stop, everything turns off. There doesnít seem to be any kind of capacitor in play.

But the thing Iím curious about is that the switch on the front light will turn off the front light but leave the back light doing exactly the same thing if the front were turned on.
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Old 10-08-23, 09:16 AM
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The Supernova taillights have no capacitors in them. They are designed to run off of the Supernovas headlight capacitor for there stand light. It appears that your taillight is going to run until the headlights capacitor is out of power everytime. I suggest making a small black bag with an elastomer to put over it.
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Old 10-08-23, 02:05 PM
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It may be a safety function, or it's just broken, or you have it wired incorrectly. If there is no standlight, then it is almost surely broken.

Okay, I didn't notice your equipment before. That taillight doesn't have a standlight, and it's only meant to work with Supernova headlights, which regulate the voltage and provide for the standlight function. Peter J. White says it should have failed. I have often wondered if that's true, your experience doesn't exactly prove him wrong though. In any event, I would get a B&M or Spanninga taillight and avoid any possibility of having it burn out.
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Old 10-08-23, 04:13 PM
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The Supernova lights run on AC. From previous reading and this post. They obviously don't play well with other manufactures lights.
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Old 11-18-23, 09:55 AM
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Old 11-19-23, 03:20 PM
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Originally Posted by Rick
The Supernova lights run on AC. From previous reading and this post. They obviously don't play well with other manufactures lights.
All of the dynamos and dynamo lights that I've encountered run on AC power.
The Supernova Triple that I've repaired delivered 5.9 volts DC to the Supernova tail light. Definitely not the same as typical dynamo tail light.
To the best of my memory, the Supernova tail light was just three red LEDs wired in series. Now I'm wondering if they might have a low value resistor wired in series, just to tolerate a bit of variation in the voltage from the headlight. As a general rule, it's a bad idea to drive a LED with a fixed voltage, and it seems odd that Supernova didn't choose to drive it with a fixed current.

I am curious as to whether a conventional dynamo tail light will exhibit the same tendency to stay powered when the OP's headlight is turned off.

Steve in Peoria
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Old 11-20-23, 09:05 AM
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I don't think the supernova taillights run off of AC. I suppose I could measure it. I have seen the circuitry, and it is very simple, seems like it's just some resistors limiting the current to the leds. Since the lights work well and don't flash much, I'm guessing it's being fed DC from the headlight.

I have my doubts about OP's wiring setup. I'm not sure all headlights interrupt the taillight wiring though.
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Old 11-20-23, 01:30 PM
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I have never used a Supernova, so I defer to Peter White on that.
https://www.peterwhitecycles.com/supernova.php

Do a word search for direct
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Old 11-20-23, 02:23 PM
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I've got a supernova dyno light set.
The front light puts out 6V DC for the rear light. I was planning to use a B&M headlamp, and my LBS owner recommended a supernova tail lamp, and ordered it up for me. It was not compatible with the B&M headlamp that puts out the DYNO AC voltage. Thankfully I caught it in the spec sheets before anything smoked. ....and my LBS owner got to order me a supenova headlamp.....

https://supernova-lights.com/en/products/e3-pure-3
- no off switch
https://supernova-lights.com/en/prod...ail-light-2-6v



since the bike is laying down, the lights are being powered by the headlamp capacitor.....

Last edited by mrv; 11-20-23 at 06:45 PM.
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Old 11-21-23, 12:39 PM
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I would be a big fan of the e3 Pure if it had more light output. The case is awesome. I have wondered if it would be brighter without the taillight, because the taillight is really bright.
Originally Posted by supernova
It is one of the smallest and brightest road-legal dynamo front lights with aluminum housing.
I feel like that is only true because of the caveats.
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Old 11-21-23, 08:41 PM
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Originally Posted by unterhausen
I would be a big fan of the e3 Pure if it had more light output. The case is awesome. I have wondered if it would be brighter without the taillight, because the taillight is really bright.
I feel like that is only true because of the caveats.
my Supernova is the first 'proper' dyno light (powered by a Kasi). While I have brighter (more lumens) battery lights, the beam pattern with a proper lens makes a significant difference. What I've noticed with my Supernova is when it's very dark (dirt roads, MUPs, that kind of thing) - it's completely fine. I prefer it to the brighter, "spot" light of my Light in Motion 700 lumen deal.
On trails, I think i prefer the spot light.
Next year I hope my budget (and wife) permit adding a Son wide body dyno and the Edelux deal.
cheers.
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