Recent content by gilesa

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    MR11 6v 6w Cygolite Rover Metro Bike Light LED Bulb Replacement?

    For longer battery life, you will need a lower wattage, with the better efficiency of LEDs compensating. You may find that one of the common 12V ones will work. The one I tested produces useful light (but not full output) from 2 1.5V alkalines and about 50% (metered) from 5V DC. It was not...
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    Dynamo 2 LED with 555 VCO step-down regulator

    I have little experience with circuit drawing software, but Kicad seems tolerable, and is free. For testing at higher speeds, I found driving the tyre with a small grinding wheel mounted in an electric drill works well. If R1 is lowered for better high-speed performance, one way to restore the...
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    Dynamo 2 LED with 555 VCO step-down regulator

    Thanks for all the detailed description. I somehow interpreted the circuit as operating at a much lower frequency, so Q2/Q3 looked like over-design. (Did you update the diagram?) That does raise the question of how you chose the inductor value and frequency? The overall design makes a lot of...
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    Solar Charger for Dusk/Dawn LED

    I think your best option might be to buy a cheap solar garden light and extract the parts. Alternatively, these controller chips are available as retail: Zetex ZXLD383. Unfortunately they come in a tiny SOT-23 package that is tricky to solder. I think there is no retail source for the more...
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    Dynamo 2 LED with 555 VCO step-down regulator

    It's good to see a different idea presented. I would like to see the long explanation as I am puzzled by Q2-Q4 and C2. It would be good to see a graph of output vs speed, with the simpler circuit included for comparison. Also, what generator are you using?
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    Experience with series capacitors and hub dynamos?

    Thanks, I think there are two good suggestion there, but perhaps slightly in conflict as adding a buck converter implies higher rectified voltage, less current, so less capacitor stress. I had considered ceramics, but the cost/benefit seems poor. From the Murata data sheet, the ESR is slightly...
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    Experience with series capacitors and hub dynamos?

    Nice parts, except that SMD and "Electrically neutral thermal path" means the central pad and two 5x0.5mm strips need to be soldered. Not for me thanks! The headlamp is a chrome-plated Sturmey-Archer with nickel-plated metal mirror, made about 1952. I made an aluminium bush to fit, threaded to...
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    Experience with series capacitors and hub dynamos?

    The reason for preferring a single LED is that I am converting an old headlamp and there is only room to mount a single emitter. Multiple LEDs in one package like Cree XHP3.5 are available, but beyond my soldering skills. I already wrecked a couple of single LED SMD devices trying to mount...
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    Experience with series capacitors and hub dynamos?

    Thanks, but that probably does not apply to the question I am interested in. The site says: "While there's not a big difference at very low and very high speed, the boost in the middle is real nice to have." The recommendation for a single LED, as I will be using, is 1650uF series capacitance...
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    Experience with series capacitors and hub dynamos?

    I have been looking at building a headlamp circuit for a hub dynamo that gives increasing output with speed. A series-resonant circuit that peaks near the expected top speed looks a good way to do that, but capacitor choice seems not straightforward. Electrolytics are compact and have adequate...
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    Electronics/ Wireless World 1994/5 Dynamo backup

    Thank you for the link. I should be more careful what I ask for, as that archive has already been a great time waster! > I presume you mean a raw LED rather than an approved 6V Dynamo LED lamp unit? Yes. I am re-using a chrome-plated headlamp with polished metal reflector that is probably...
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    Electronics/ Wireless World 1994/5 Dynamo backup

    I am reworking the LED conversion of my winter bike with S-A Dynohub and still deciding on the electronics side, so this looks very interesting. Is it possible to post or link the circuit, or better the whole article? Otherwise, a trip to the public library and probably a long wait. The...
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