Dynamo connection in series or parallel?
04-22-23, 01:15 PM
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Dynamo connection in series or parallel?
Hi, I can't seem to find this simple detail - can a front light and a back light be connected to a bottle dynamo in different ways?
If the dynamo has one output, and the ground is running through the frame, do I have to insert both front and back wires directly to the dynamo?
Or I can run a wire to the front light and from there to the back light?
It's a vintage bike, so those are old type bulbs, I think it's around 3W in front and 0.3W in the back.
Any information would be appreciated, cheers!
If the dynamo has one output, and the ground is running through the frame, do I have to insert both front and back wires directly to the dynamo?
Or I can run a wire to the front light and from there to the back light?
It's a vintage bike, so those are old type bulbs, I think it's around 3W in front and 0.3W in the back.
Any information would be appreciated, cheers!
04-25-23, 01:39 PM
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04-25-23, 01:57 PM
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04-25-23, 02:55 PM
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Thread moved from General to Electronics.
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04-25-23, 03:13 PM
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The loads should be connected in parallel so they are operating at the same voltage.
I'm using a hub dyno, so two wires to the light. And the light has a DC feed to the tail light. (Brand is SuperNova - caused me a bit of a head ache as I didn't know I had purchased a DC tail light from my LBS.... so they up sold me on a new head lamp. Good thing I like them a lot!)
It sounds like the dyno is grounded to the fork (or maybe rear tire, so frame?) - through the attaching bolt? Is that the same for the front / rear lights? (I guess I'm not sure about conducting to the rear light through the head set and what not....)
Anyway - seems like you should have a return (or ground) from the rear light to the fork. Then a common power from the dyno making a "power node" for the lights. The lights would be at the same voltage (A/C).
I say parallel attachment - and you can tell everyone you read it on the internets!
twice:https://www.quora.com/It-is-known-th...ed-in-parallel
I'm using a hub dyno, so two wires to the light. And the light has a DC feed to the tail light. (Brand is SuperNova - caused me a bit of a head ache as I didn't know I had purchased a DC tail light from my LBS.... so they up sold me on a new head lamp. Good thing I like them a lot!)
It sounds like the dyno is grounded to the fork (or maybe rear tire, so frame?) - through the attaching bolt? Is that the same for the front / rear lights? (I guess I'm not sure about conducting to the rear light through the head set and what not....)
Anyway - seems like you should have a return (or ground) from the rear light to the fork. Then a common power from the dyno making a "power node" for the lights. The lights would be at the same voltage (A/C).
I say parallel attachment - and you can tell everyone you read it on the internets!
twice:https://www.quora.com/It-is-known-th...ed-in-parallel
04-25-23, 04:29 PM
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Parallel. If the bulbs are incandescent, tail light should be 6v, 0.6 watt and front light 6v and 2.4 watts.
The bulb contacts and contacts in the light to the bulbs should be cleaned up to avoid any resistance from corrosion.
Note that if you go fast down a hill, you can produce overvoltage and blow out the bulbs. Years ago some have installed zener diodes to protect against that. I had a pair of zener diodes on my wiring but that was so long ago I do not recall the details. I think my zener diodes were 8 volt. You might be able to find more on that topic with help from Google. Or, do not go fast down hills and skip the zener diodes.
The bulb contacts and contacts in the light to the bulbs should be cleaned up to avoid any resistance from corrosion.
Note that if you go fast down a hill, you can produce overvoltage and blow out the bulbs. Years ago some have installed zener diodes to protect against that. I had a pair of zener diodes on my wiring but that was so long ago I do not recall the details. I think my zener diodes were 8 volt. You might be able to find more on that topic with help from Google. Or, do not go fast down hills and skip the zener diodes.
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04-27-23, 09:58 AM
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Always parallel. You can either run the tail light cable in parallel from the dynamo or from the front light. And you may want to look into modern LED lights. There are "vintage" looking ones since these old style incandescent bulbs are not much brighter than a candle light. Even old bottle dynamos do provide around 3W output and will support new LED lights. The same as modern hub dynamos. I retrofitted an older 1980s Gazelle with modern but vintage looking LED lights.
05-02-23, 02:18 PM
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...
Note that if you go fast down a hill, you can produce overvoltage and blow out the bulbs. Years ago some have installed zener diodes to protect against that. I had a pair of zener diodes on my wiring but that was so long ago I do not recall the details. I think my zener diodes were 8 volt. You might be able to find more on that topic with help from Google. Or, do not go fast down hills and skip the zener diodes.
Note that if you go fast down a hill, you can produce overvoltage and blow out the bulbs. Years ago some have installed zener diodes to protect against that. I had a pair of zener diodes on my wiring but that was so long ago I do not recall the details. I think my zener diodes were 8 volt. You might be able to find more on that topic with help from Google. Or, do not go fast down hills and skip the zener diodes.
I think some headlights had this built in... maybe a Lumotec? It's been quite a while since I had to think about it.
Modern LED headlights tend to have a suitable protection diode built in, and provide protection for the taillight.
Steve in Peoria
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05-03-23, 05:31 AM
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on the chance that there are questions about this, a bidirectional zener diode rated around 8v and 3 watts is suitable. I can look up the part number if anyone is interested.
I think some headlights had this built in... maybe a Lumotec? It's been quite a while since I had to think about it.
Modern LED headlights tend to have a suitable protection diode built in, and provide protection for the taillight.
Steve in Peoria
I think some headlights had this built in... maybe a Lumotec? It's been quite a while since I had to think about it.
Modern LED headlights tend to have a suitable protection diode built in, and provide protection for the taillight.
Steve in Peoria
Yes, the modern LED lights have overvoltage built into the headlamps. I think that most or possibly all LED taillights do not, thus they have to be wired to the headlight so that the headlight provides the overvoltage protection to the taillight.
Looking at my previous comments, at that time I should also have made another comment: If one bulb burns out, either from overvoltage, vibration, or just plain long life, all of the power will then go into the other bulb which will then have a greatly reduced lifespan. So, if you buy incandescent bulbs for it, assume you will be replacing both bulbs every time you need to replace one.
