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but I've a comment or two (speaking as an EE design engineer).
Switching power converters (I've designed maybe a dozen or two,
not a specialty, but had to do them once in a while,
albeit at low power levels (up to about 80W)) can do "nasty"
things, or they can be well behaved. Depends upon the circuit
design and the requirements it's made to meet (assuming the
designer met requirements).
The output will always have some voltage variation or
"oscillation" seeing as how it's switching (in the name),
but the output variation up/down may be only a few millivolts
if that's how it's designed. The variation will be at the
switching frequency (that may or may not be constant, but
ones I've done have been fairly constant). Most
of the electronic-toy chargers I've seen in recent
years are all switchers (100% of those that are the typical
100~250V input ones). You need an oscilloscope to see
the output variations (ripple) or any other spurious
spikes going on.
Some designs require a minimum load, some don't. Those
that require a minimum load can have undesired output when
unloaded (I did only one of those, and with no load the
output voltage goes up a lot and becomes unregulated).
If one hot-connects one of those types it may start with
a high output voltage that drops to the regulated one a bit
after that. A voltmeter should be able to characterize such
a supply (when unloaded).
Mike K.
John Fimognari wrote:
>From the review it looks ok. If you are going to use it as a USB switch make certain that the voltage is regulated to 5 volts. You will need a digital voltmeter. To be honest I would use the battery design posted on the CHDK site. Switched mode power supplies can generate some nasty spikes when used on a no load application. They are know to generate voltage oscillations and generate voltage spikes. I do not have the article handy. National Semiconductor have an application note on the use of regulators and switching regulators on their web site. After reading the article I would be reluctant to use any sort of regulator device as an USB trigger. If the available voltage is too high, in the servicing industry, they generally use a series resistor and a zener diode across the rail for a simple volt drop application. Or you can use series diodes are voltage droppers. On 7/3/09, robertpelc <robertpelc@...> wrote:Does anyone have any knowledge about whether an Energizer Energi To Go cell phone charger can be used as a base for a USB switch? It comes with a couple of lithium AA batteries and upconverts 3v to 5v. They seem to be readily available for under $20. The Ricoh CA-1 can be hard to get. Bob Pelc------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/StereoDataMaker/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/StereoDataMaker/join (Yahoo! ID required) <*> To change settings via email: mailto:StereoDataMaker-digest@yahoogroups.com mailto:StereoDataMaker-fullfeatured@yahoogroups.com <*> To unsubscribe from this group, send an email to: StereoDataMaker-unsubscribe@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
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