Proposed XP-G/XP-E dynamo headlight/taillight

ihab

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Oct 21, 2009
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Hi folks,

Thank you for all your kind assistance with my previous posting. Here is a proposed circuit:

DynamoLight.png


It uses as a basic Martin's circuit #12:

http://pilom.com/BicycleElectronics/DynamoCircuits.htm#AutoMode

At 700mA, the taillight XP-E string drops 4.4V, so the standlight cap is just connected across them directly. The headlight XP-G string requires the circuit mentioned here:

https://www.candlepowerforums.com/posts/2704446&postcount=61

Any feedback? Cheers and regards,

Ihab
 

yellow

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I think two (even just one) powerled at the same current than the front ones in the taillight is an offense to anyone else in traffic.

4 pc. red 5mm @ 20-50 mA each (telux led) is more than appropriate
 

ihab

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Oct 21, 2009
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I think two (even just one) powerled at the same current than the front ones in the taillight is an offense to anyone else in traffic.

I see ... makes sense. Thanks for the tip.

4 pc. red 5mm @ 20-50 mA each (telux led) is more than appropriate

Ok but I'm a bit confused. The info I can find about Telux LEDs is here:

http://www.vishay.com/leds/list/product-83138/

and the package seems to be 7.62mm across, not 5mm. Are we looking at the same things?

Regards,

Ihab
 

ihab

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... 4 pc. red 5mm @ 20-50 mA each

Ok, I give up. I'm stumped. How do I build a circuit that pushes a limited current through the 4 taillight LEDs while allowing full current to flow through the headlight LEDs?

Thanks,

Ihab
 

znomit

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...Put the taillight led in parallel with the front leds and use a resistor to limit the current to say 100mA max.

Or...Run the tail light off the supercap

BTW, a 555 flasher runs nicely off a supercap.
You could do front and rear flashers with a 1/10 duty cycle for ok runtimes and the flashing will be noticable alongside your steady lights.
 

ihab

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Oct 21, 2009
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...Put the taillight led in parallel with the front leds and use a resistor to limit the current to say 100mA max.

Ok, here's what I now have:

DynamoLight2.png


I have no component values figured out in any sort of detail. That said, I feel like it's enough of poking around on paper: I think my next step is to get some emitters, go to the electronics lab where I work, hook up a power supply and a multimeter, and take it from there.

Thanks a lot folks!! I'll check back when I make some more progress.

Ihab
 

pe2er

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Dec 22, 2007
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Europe - Holland - Almere
The way you have it set up right now, C2, intended as a standlight provision for LEDS 5-8, will also try to illuminate LEDs 1-4 through R3 and R2. You can solve that by adding a diode in series with R2, or connecting R3 to the junction between LED 5 and LED 6 (it will then only power LEDs 6, 7 & 8).
DynamoLight2.png

For what it's worth, I Am pretty happy with my 1 Watt LED taillight. Do not think that it is overkill at all!
dscf0014h.jpg
 

Tweel

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Nov 25, 2000
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Seattle, WA USA
Hi folks,

Thank you for all your kind assistance with my previous posting...

Any feedback? Cheers and regards,

Ihab

Hi,

How is this project going? I'd like to try something similar. How are you making and housing the circuit board? What are you using for a light enclosure?

--Tweel
 
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