Just trying to figure out why I can't find any power supplies (wall warts) that deliver the appropriate voltage? For example went to goodwill looking for a ps that would deliver around 5V and 500 mA, found a couple that said 4.2V or something like that. Got home and checked with Vmeter and found out it was like 7V. Is this just because there is no load on it or what? I'm somewhat new at electronics just trying to figure this out, don't want to have to add a regulator to my project. Thanks in advance.
2007-01-29 18:23:39 · 2 answers · asked by FastEddie 5 in Science & Mathematics ➔ Engineering
A good many of the power supplies are unregulated - they are made for a specific devise that draws a relatively steady current that loads the power supply down to a particular voltage range.
The best and most accurate test you can perform to see if a power supply will work on a specific devise is to check the DC IN jack for specifications (i.e. 12VDC IN) and then power it up with a power supply rated at or slightly below this specification and measure the voltage while the devise is in operation.
Generally 10% one way or the other won't effect its performance any.
Good luck.
2007-01-29 18:36:03 · answer #1 · answered by LeAnne 7 · 0⤊ 0⤋
Exactly right. You need a load to get the voltage in range. Power supplies like that are usually designed to be cheap and lightweight. They aren't designed to maintain a tight voltage tolerance from no load up to the rated load.
It should be fine depending on what you plan to use it for.
2007-01-30 02:35:42 · answer #2 · answered by tom_2727 5 · 0⤊ 0⤋