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Old March 17th 17, 09:53 PM posted to rec.bicycles.tech
SMS
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On 3/17/2017 12:58 PM, Joerg wrote:
On 2017-03-17 12:11, sms wrote:
On 3/13/2017 12:28 PM, Joerg wrote:

snip

You could stick in a Murata LXDC55FAAA-203
http://power.murata.com/data/power/LXDC55FAAA-203_data_sheet_E.pdf
instead of the zener and do a USB version also with only three parts.
But I know that you love designing your own switchers.


$3.50? Mon Dieu! :-)


I got some of the Murata LXDC55FAAA-203 units from Digikey for use at
work. I guess I didn't realize from the picture on the data sheet just
how tiny these things are. Maybe I'll buy some more and try building
some dynamo to USB adapters.


Be carful with that 16V abs max input limit. When the load current drops
this can easily be exceeded by a dynamo, big time. You could burn off
the excess with a zener diode or TVS (though _not_ MOV) but these have
large tolerances and could burn out if not well heat sinked.

I think you need somthing automotive here, some circuit that can stomach
50V or more.


I'd just stick a 15V 5W zener in there for the rare times that the
dynamo is exceeding 11VAC. If I were going to sell these I'd do
something more robust.


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