Calculating resistors required

From: Danny T (danny_at_nospam.oops)
Date: 12/31/04 

Date: Fri, 31 Dec 2004 11:10:01 +0000

Hi all,

Sorry for more reeeally basic questions, but advice I've been given by
different people conflicts, and some of the reading on the web is a bit
over my head, whereas you guys always seem to explain things well :)

I've got a programmed PIC16F chip, and I want to wire it up to a few
things... My power supply is 4AA batteries (about 6V), but my chip wants
about 5V. The switches connected to my chip also want about 5V.

My motor is driven from an output pin of the chip (which I guess, is
5V?), but the motor is 3V. My LEDs are 3V too.

I guess I need a resistor to reduce my 6V to 5V, which can then be
connected to the chip + input switches. The 5V output would be find for
the 5V LEDs, but I guess I need another resistor for each motor.

It's also been mentioned that my switches should be connected to 0V via
a resistor when "off", and 5V when "on". I don't understand the
reasoning for this :-\

Also, if I was to need 6V to drive something, but the output from my
chip is less, though my main supply is enough - how do I go about
changing a 5V (I think!) output, to 6V? I've been reading about
transistors thinking they do what I want, but I've just confused myself
even more!

Many thanks! 

-- 
Danny

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