Help designing circuit for dynamo-charged-battery-driven LED lights

[Tally-ho]

A very clever way to use (two) dynamo(s) friction to slow down AND to charge batteries :
:naughty:
http://cyclurba.fr/velo/78/frein-dynamo-accu-led-velo-eclairage-energie-freinage-recuperer.html

Dynamo are attached to rear-brakes and set to touch the wheel first when brake-command is used lightly. Brake pads are kept for quick/urgent stop.
Current from a dynamo is AC, not DC, so he used diodes bridge.

 

[seanspotatobusiness]

A very clever way to use (two) dynamo(s) friction to slow down AND to charge batteries :
:naughty:
http://cyclurba.fr/velo/78/frein-dynamo-accu-led-velo-eclairage-energie-freinage-recuperer.html

Brilliant! I had a similar idea but didn't think of a way to implement it - maybe I could do this at some later stage, using a different circuit, and using more (cheap will do) dynamos.

Here's the Google translation - understandable enough to follow.

 

[Calina]

A very clever way to use (two) dynamo(s) friction to slow down AND to charge batteries :
:naughty:
http://cyclurba.fr/velo/78/frein-dynamo-accu-led-velo-eclairage-energie-freinage-recuperer.html

Dynamo are attached to rear-brakes and set to touch the wheel first when brake-command is used lightly. Brake pads are kept for quick/urgent stop.
Current from a dynamo is AC, not DC, so he used diodes bridge.

Pas bête mais j'ai des doutes sur la capacité de recharge. Dès que les piles seront sollicitées pour un trajet le moindrement long, elles ne suffiront plus à la tâche.

Interesting idea, but I doubt it will charge the batteries sufficiently.

The resistance of a bottle dynamo is not that big an issue anyway; ten watts at most will be lost to friction because of the dynamo, or to put it another way, one to two km/h. This is a solution to a false problem.

 

[seanspotatobusiness]

Sacre bleu! My thread is derailing!

 

[Calina]

Non!
We are still discussing a dynamo charging battery circuit. ;-)

 

[seanspotatobusiness]

Non!
We are still discussing a dynamo charging battery circuit. ;-)

I know but I was hoping to keep the topics separate, 'cause for me at least, they're entirely different projects. I don't really want to discuss that one here and then come back to my other ones later in the thread 'cause it will be confusing for me (and hopefully others!) to follow again in the future!

 

[seanspotatobusiness]

Steve, I've ordered my components but didn't pay much attention and it turns out that my ZXSC310 is a ridiculously small SMD. It looks like it would take a robot to solder something this small and fiddly. It's smaller than the usual blob of solder I expected to use on each leg. Is it available with proper legs or only SMD? If so, how do you refer to the sort with "proper legs"?

I was hoping to test the circuits on solderless breadboard and then make it permanent on strip board but I don't think I can connect this component in either situation.

 

[Steve K]

Steve, I've ordered my components but didn't pay much attention and it turns out that my ZXSC310 is a ridiculously small SMD. It looks like it would take a robot to solder something this small and fiddly. It's smaller than the usual blob of solder I expected to use on each leg. Is it available with proper legs or only SMD? If so, how do you refer to the sort with "proper legs"?

I was hoping to test the circuits on solderless breadboard and then make it permanent on strip board but I don't think I can connect this component in either situation.

The package is a SOT type. SOT stands for small outline transistor, I think (and could be very wrong). I think some of my pictures showed how I soldered it to copper-clad board. I lifted at least one of the leads, and left 3 or 4 to be soldered to the board. The lifted leads had 30 ga "wire wrap" wire soldered to them in order to connect them to the other components. The copper clad board is cut into various pads with a dremel tool and the thin cut-off discs. I think the pictures may explain it better than words can.

For breadboarding, you may be able to attach 30 ga wires to the leads. It's risky, because the leads can't handle a lot of stress, and 30 ga is too small for the breadboard. There are small circuit boards called "surf boards" that are used to mount a few surface mount components, and then the surf board has leads that let it be mounted in the breadboard. They are a bit expensive, and I found it more practical to just hack up a small piece of copper-clad board to do the same thing.

This does start to get involved, since you will need a dremel, some 30 ga wire, a stripper for the 30 ga wire, some copper clad board, etc. Not a big deal if you think you'll use it again, but a bit of a waste otherwise.

You'll also want to have a good magnifying glass to check your solder work and check for bits of copper when you cut slots in the copper board. If you aren't a young kid, the unassisted eye can't always detect some solder problems.

regards,
Steve K.

 

[seanspotatobusiness]

Hey Steve, they are a bit expensive but I decided to get some adaptor boards anyway. If I get into electronics after this, I could try making my adaptors, although I imagine it must be very, very tricky to get the pads in just the right positions... and if it were something bigger than SOT, it becomes even less feasible.

Another practical issue that I'm facing is the connections; I will want to be able to remove the lamp when I leave the bike locked up and connect it again when I need it. I'm going to need two electrical connections to the dynamo and two or three connections to the rear lamp (for main light and stand-light - they could both share the same ground wire). One option would be bullet connectors but that's a lot of plugging/unplugging. Ideally, I'd have a single five/six-pin connector so that I can do them all at once. Any ideas for such a connector? I did think of a computer molex but that's only four pins and I don't know whether water ingress could be an issue.

 

[Steve K]

Soldering the little stuff is a challenge. You may want to prototype the circuit on the breadboard, but I recommend building the final version on copper-clad board with surface mount parts. The ideal would be to lay out a board, have the board made, install surface mount parts, and be done. This produces a better final result, but is more expensive, etc.

by the way, if you use surface mount parts, get a pointy tweezer for handling the parts. It really makes things easier.

Connectors.... you might want to search through the archives and see what has been discussed before. Water resistance is a concern, and if you mate/de-mate the connector daily, you'll want a connector designed for it. Computer grade connectors are intended to only be mated & de-mated a few times. I've heard people suggest automotive trailer connectors. No idea how good they are, but at least they should be somewhat water resistant and can carry a few amps.

regards,
Steve K.