ANY DIODE/RESITOR EXPERTS OUT THERE?
Han Solo
I understand how to read the color codes and reach an Ohm. BUT How do I
convert the OHM to a voltage?? For instance:
I am making a custom project, ONE 12v 2.3amp(NOT ma) battery will power several units
together, some units require a 9volt battery at ? ma and some require a 1.5 volt at ?ma.....I know I can
accomplish this through the use of resitors BUT I can't figure out which ones to use!!!!! Here's a good
question:
If I need a resitor to regulate power from a 12volt 2.3a battery into a device that requires the
power req of a common AA1.5v battery, what type of resitor do I use and most important
WHY??? How do I figure this out??
Thanks!!!
John Nagle
>I'm new to resistors and diodes, I've read tons of book and
>am still a little lost.
>I understand how to read the color codes and reach an Ohm. BUT How do I
>convert the OHM to a voltage?? For instance:
> I am making a custom project, ONE 12v 2.3amp(NOT ma) battery will
>power several units
>together. Some units require a 9volt battery at ? ma and some
>require a 1.5 volt at ?ma.....I know I can
>accomplish this through the use of resistors BUT I can't figure out
>which ones to use!!!!! Here's a good question:
> If I need a resistor to regulate power from a 12volt 2.3a
> battery into a device that requires the
> power req of a common AA1.5v battery, what type of resistor do I
> use and most important WHY??? How do I figure this out??
Where to begin?
Well, if the device you're powering draws a known and constant amount of
current, you really can use a resistor. Otherwise, you need something
fancier. What are you trying to power? Tell us more.
The basic rules for this sort of thing are:
1. I = E/R which means current = voltage / resistance
2. The current through two things in series is the same.
3. The voltage across two things in parallel is the same.
Given those three rules, you can figure out what's going on in most DC
circuits. Get a few resistors, a multimeter, and a battery, and try
various arrangements of resistors in series and parallel. Measure
current and voltage at various points. Try to calculate what the
measured values should be. Start with two identical resistors in
series. Then try two identical resistors in parallel. Then try
different resistors in series, and different resistors in parallel.
For this work, use only resistors bigger than 1K or so, and a 9V battery,
and you shouldn't overheat the resistors. (The wattage turned into heat
in a resistor is calculated by W = E*I, where E is the voltage and
I is the current. If W exceeds the wattage rating of the resistor,
the resistor will overheat, and if it exceeds it by a lot, it will burn up.)
Try reading sections 1.01 through 1.04 of "The Art of Electronics",
which explains this. The whole book is a bit much to tackle (it's for
grad students) but those sections will explain resistors clearly.
It's hard to explain this without diagrams.
John Nagle