Hi,

I gots meself a book from the library "Starting Electronics"!  And this
Saturday, I'm going down to Brighton to visit a Maplin store and get some
kit to get started.  But after reading the book I am left clueless about one
thing with power supplies.  Say I wanted to power this
http://www.maplin.co.uk/products/Module.asp?CartID=0207091357491453061&modul
eno=11711&modulecode= lovely laser (just 'cos it looks cool).. It takes a 3V
power supply, the operating current is 40 to 70mA, and the output power is
3mW.  However, I don't know how to work out (for example) what
battery(/batteries) to use (assuming it's on its own circuit).  Theres not
much on power (watts etc.) in the book so I really don't know how to go
about it.  I could use (off the top of my head) 2 AAA-size batteries in
series to generate a 3V supply, but does that give 40 to 70 mA of current?
Am I right in thinking the source decides the current, or does the load draw
from it?  Just need a little clear-up in my head :)

Thanks,
Kieren

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body