http://citycyclingedinburgh.info/bbpress/ CityCyclingEdinburgh Forum » Topic: Warning for gadget geeks en Sat, 16 May 2026 21:25:08 +0000 http://citycyclingedinburgh.info/bbpress/topic.php?id=1235#post-11430 Tue, 17 Aug 2010 12:27:17 +0000 spytfyre 11430@http://citycyclingedinburgh.info/bbpress/ <p>@chdot - to charge a phone or other expensive device, lights yes. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=1235#post-11338 Fri, 13 Aug 2010 16:16:44 +0000 steveo 11338@http://citycyclingedinburgh.info/bbpress/ <p>Fairly simple to get around if your not interested in efficiency. An LM7805 can take up to about 37v input with a smallish heat sink and out put a good, clean, constant 5v. Any power over 5v gets expelled as heat.</p> <p>Hook that up to the dynamo along with a simple bridge rectifier made from 4 diodes and you have exactly the same 5v you get on your USB. </p> <p>They use these chips in most pc power supplies. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=1235#post-11333 Fri, 13 Aug 2010 15:51:30 +0000 chdot 11333@http://citycyclingedinburgh.info/bbpress/ <p>"I would never trust a dynamo"</p> <p>to do?</p> <p>The thing about dynamos is that their voltage isn't entirely linear - doesn't keep going up with speed.</p> <p>The voltage also depends on load - which is why, if you've ever used one, you'll know that if one bulb goes, the other is likely to soon after!</p> <p>I suspect the charger wouldn't have been a particularly high load, and whoever designed the circuit wouldn't have allowed for the fact that it was going to be used on a small wheeled bike (on very steep hills...) </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=1235#post-11331 Fri, 13 Aug 2010 15:35:31 +0000 spytfyre 11331@http://citycyclingedinburgh.info/bbpress/ <p>I am tempted to make a solar charger from 4 solar powered garden lights and an old USB extension cable, put the lot inside plastic pocket folders (like for CCG geeks) and seal them up... I would never trust a dynamo. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=1235#post-11290 Fri, 13 Aug 2010 10:45:43 +0000 Wilmington's Cow 11290@http://citycyclingedinburgh.info/bbpress/ <p>""I made a charger using a circuit from the internet"</p> <p>I think I've spotted where he/she went wrong."</p> <p>Must have had a REALLY long cable... </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=1235#post-11289 Fri, 13 Aug 2010 10:33:50 +0000 cb 11289@http://citycyclingedinburgh.info/bbpress/ <p>"I made a charger using a circuit from the internet"</p> <p>I think I've spotted where he/she went wrong. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=1235#post-11287 Fri, 13 Aug 2010 10:18:46 +0000 chdot 11287@http://citycyclingedinburgh.info/bbpress/ <p>"Actually I don't have many photos of the trip. I made a charger using a circuit from the internet so that I could charge my camera phone from the front hub dynamo. This worked well for a while before cooking my phone down a long decent!"</p> <p>Posting on a Moulton Forum. </p> <p>Bike in question (touring Switzerland)</p> <p><img src="http://xa.yimg.com/kq/groups/10299015/sn/2057449074/name/Dsc01373.jpg"></p> <p>"I am happy to report that my 1963 bicycle performed superbly with no problems whatsoever other than punctures. The F-frame really is an awesome load carrier" </p>