On Wed, Jan 7, 2009 at 7:36 AM, Mike Dawson <span dir="ltr"><<a href="mailto:mikeofmanchester@gmail.com">mikeofmanchester@gmail.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Dear All,<br>
<br>
We tried to create a sewing machine based trial to power an XO - we<br>
geared it at about 90:1 so that the two dynamos should spin at about<br>
the same speeed as they would on a bike.<br>
<br>
When connecting the bike light it does light - a little dimmer than<br>
normal - but the digital voltmeter for some reason when just starting<br>
slowly to spin the wheel by hand registers 0.1V or so when it's going<br>
smoothly at full speed it registers absolutely nothing. I tested<br>
measuring a few batteries and it seemed fine.</blockquote><div><br>Most "bicycle dynamos' will produce alternating current. The XO requires direct current for charging. A light bulb can operate off either.<br><br>
I suggest you re-test the bike dynamo with the AC setting of your volt meter.<br><br>If this is the case, you can use a bridge rectifier to change the alternating current into direct current, at the cost of about 1.4 volts.<br>
<br></div></div><br>-- <br>Steve Holton<br><a href="mailto:sph0lt0n@gmail.com">sph0lt0n@gmail.com</a><br>