znomit
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Yes its normal when free spinning.
Dyno powered triple cutter R2
- Thread starter znomit
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Yes its normal when free spinning.
Been a while between builds but heres my latest. Smaller, easier, brighter, smarterer. Theres been a few ideas from here and over on MTBR that I wanted to try out, and I wanted to try a reflector setup. Heres what I came up with...
Firstly, I've been chasing lumens for a few years now, going from 2 to 3 to 4 to five and then back to three LEDs. Last year while in between builds I resorted to using an old dual cree p3 build, using those nice tight cree optics. Had a good ride with it. Occurred to me two LEDs with the right optics should be enough.
...
Hi znomit,
I plan to build Martin's boost circuit combined with a standlight as you have done, but I'd very much like to try 3 leds - 2 before the standlight cap and one after. Have you tried this or perhaps thought it through? Any ideas as to what you'd need to change to have say 2 XR-es with one used as the final standlight? In previous discussion syc suggested just putting the first of 3 leds in series on the positive rail (ie; after the smoothing cap junction and before the diode feed to the standlight cap). He felt that this would retain the approx 7v load across the diode/supercap part of the circuit. I tried this but could never get it to work - from memory only LED 1 lit up with any real activity. At the time I couldn't figure out what was happening and I just lost patience! I now have a breadboard so I thought I'd tackle the problem again. Any pointers much appreciated!
Sam (Adelaide).
Dyno powered twin with standlight a la Znomit's design
Hi Znomit and Team,
Just reviving this thread a bit... I've just finished my version of Znomit's twin-LED standlight, posted here a couple of years ago. After the usual couple of debugging sessions (finding dry joints and a couple of veroboard tracks I'd neglected to scratch out) I fired it up. Cries of 'It works, it works...' from the bike shed! This is my first attempt at a 'tuned circuit' light (first that worked anyway) and as I don't yet have it on a bike, I have no real idea if it's actually going to be brighter that the 'standard' #2 circuit. But it's looking good.
Some variations from Znomit's design:
- I've used 2 x XR-Es rather than his XP-Es, simply because I had them to hand, and (to be honest) because I didn't pay close enough attention to his write-up and just grabbed 2 DX XR-Es from the parts box! I'm also just using the cheap DX 8 degree 'clip on' XR-E optics. As this combination is so very convenient to put together I'll probably leave them as they are for now. But I would be interested to know how many lumens I'm likely to be missing out on relative to the XP-Es...?
- I ended up using 470uf/16V tuning caps. Don't ask me why - probably because I didn't have my glasses on and missed the extra '0'. Will this mean I've actually built a 220uf bi-polar? Will my peak voltage be at an extra low speed? Is 16v tolerance too low for a twin LED set up?
- used a 150 ohm R on the standlight to enhance run time.
- no switch because I want this light to be on all of the time.
I'll probably house this in a scrap of 40mm X 25mm tube I have with 2 holes cut out as per Znomit's design. The standlight (with a 1F/5.5V cap) stays bright enough to walk around at night for around 5 minutes and is still quite visible at 10.
I'm also thinking how I could incorporate a tail light. Could I just insert a red XR-E (or XP-E) in place of the 2nd white LED (the one fed by the supercap)?
I've been re-reading everything I can find on CPF on dynamo lights (yep - I'm on holiday) in an attempt to understand once and for all the several different concepts that have been brought together in the various circuit ideas raised in this and other stand-light-related threads. It seems to me that - when all is said and done - for every-day commuter use (with a hub dynamo), it's difficult to improve on the following combination:
- bridge rectifier
- 1, 2 or 3 power leds
- large (4700uf) smoothing capacitor
- maybe a single string of tuning caps (as per Martin's #6) to boost low speed lumens
- maybe an integrated tail light as per #3,4 or 9.
I do note Steve Kurt's recent mention of a 'charge pump' arrangement for a tail light - maybe that could constitute an 'improvement' on the above!
And ofcourse there are rumours of K-tronik's/Dean's new low-speed 'MTB standlight' circuit...
OK - where's my hacksaw and file?
Savvas.
Hi Znomit and Team,
Just reviving this thread a bit... I've just finished my version of Znomit's twin-LED standlight, posted here a couple of years ago. After the usual couple of debugging sessions (finding dry joints and a couple of veroboard tracks I'd neglected to scratch out) I fired it up. Cries of 'It works, it works...' from the bike shed! This is my first attempt at a 'tuned circuit' light (first that worked anyway) and as I don't yet have it on a bike, I have no real idea if it's actually going to be brighter that the 'standard' #2 circuit. But it's looking good.
Some variations from Znomit's design:
- I've used 2 x XR-Es rather than his XP-Es, simply because I had them to hand, and (to be honest) because I didn't pay close enough attention to his write-up and just grabbed 2 DX XR-Es from the parts box! I'm also just using the cheap DX 8 degree 'clip on' XR-E optics. As this combination is so very convenient to put together I'll probably leave them as they are for now. But I would be interested to know how many lumens I'm likely to be missing out on relative to the XP-Es...?
- I ended up using 470uf/16V tuning caps. Don't ask me why - probably because I didn't have my glasses on and missed the extra '0'. Will this mean I've actually built a 220uf bi-polar? Will my peak voltage be at an extra low speed? Is 16v tolerance too low for a twin LED set up?
- used a 150 ohm R on the standlight to enhance run time.
- no switch because I want this light to be on all of the time.
I'll probably house this in a scrap of 40mm X 25mm tube I have with 2 holes cut out as per Znomit's design. The standlight (with a 1F/5.5V cap) stays bright enough to walk around at night for around 5 minutes and is still quite visible at 10.
I'm also thinking how I could incorporate a tail light. Could I just insert a red XR-E (or XP-E) in place of the 2nd white LED (the one fed by the supercap)?
I've been re-reading everything I can find on CPF on dynamo lights (yep - I'm on holiday) in an attempt to understand once and for all the several different concepts that have been brought together in the various circuit ideas raised in this and other stand-light-related threads. It seems to me that - when all is said and done - for every-day commuter use (with a hub dynamo), it's difficult to improve on the following combination:
- bridge rectifier
- 1, 2 or 3 power leds
- large (4700uf) smoothing capacitor
- maybe a single string of tuning caps (as per Martin's #6) to boost low speed lumens
- maybe an integrated tail light as per #3,4 or 9.
I do note Steve Kurt's recent mention of a 'charge pump' arrangement for a tail light - maybe that could constitute an 'improvement' on the above!
And ofcourse there are rumours of K-tronik's/Dean's new low-speed 'MTB standlight' circuit...
OK - where's my hacksaw and file?
Savvas.
znomit
Enlightened
Re: Dyno powered twin with standlight a la Znomit's design
Hi Savvas
See the posts here on tuning:
I've actually gone off the idea of tuning. The problem is you want max light at max sustainable speed (probably around 40kph for me if I'm in a hurry and have a bit of a tailwind or incline).... but spend most of your time doing 20-30kph so you actually want the circuit tuned best there too. I think its better just to have a flat curve, as in Martins C7. Just two LEDs gives you heaps of light at speed and ~100lm at 5kph. And its a very simple circuit so less chance of problems.
Similarly for simplicity and redundancy I run a small white light instead of a stand light (good for puncture repairs), and a couple of battery taillights (80hrs from 1AA) instead of a wired taillight.
Most of last winter I used a B&M Cyo instead of my DIY lights because of the very good beam pattern and compact size. :shrug:
Hi Savvas
See the posts here on tuning:
I've actually gone off the idea of tuning. The problem is you want max light at max sustainable speed (probably around 40kph for me if I'm in a hurry and have a bit of a tailwind or incline).... but spend most of your time doing 20-30kph so you actually want the circuit tuned best there too. I think its better just to have a flat curve, as in Martins C7. Just two LEDs gives you heaps of light at speed and ~100lm at 5kph. And its a very simple circuit so less chance of problems.
Similarly for simplicity and redundancy I run a small white light instead of a stand light (good for puncture repairs), and a couple of battery taillights (80hrs from 1AA) instead of a wired taillight.
Most of last winter I used a B&M Cyo instead of my DIY lights because of the very good beam pattern and compact size. :shrug:
unterhausen
Enlightened
- Joined
- Jan 16, 2009
- Messages
- 275
Re: Dyno powered twin with standlight a la Znomit's design
I went to a Supernova E3 asymmetric for the same reason. I was riding with my triple DIY, and another rider had a Edulux. I was putting out just as much light, but mine was spread all over, and his was where we needed it. I like the standlight too, never bothered much with my electronics on the diy lights.
Calina
Enlightened
Pics are gone, here too.
