[simpits-tech] Resistor for LEDs?

[Joseph Fagner]

Q2.  I understand what you are asking.  He wants to know that if he set
up a power strip (i.e power coming into a bus bar with multiple
connecting site to feed power to multiple LED's) would he need to have a
resistor for each LED or could he put one resistor between the bus bar
and power line?  I believe you would need to use a resistor for each
LED, as if you start lighting several LED's, you will be running an
increasing current through that one resistor as the multiple LED's
produce an increasing load.  If the resistors wattage is rated high
enough you could probably get away with just one, but I think it would
be safer to use a 1/8 watt resistor for each LED.  

Any one disagree?  I'm no electronics expert but this is what I plan on
doing.

Jay

-----Original Message-----
From: simpits-tech-admin@simpits.org
[mailto:simpits-tech-admin@simpits.org] On Behalf Of Stig Joergensen
Sent: Monday, December 23, 2002 1:18 PM
To: simpits-tech@simpits.org
Subject: RE: [simpits-tech] Resistor for LEDs?

Mike 

q1:

do you know this law: U=R*I that is Voltage = Risistance * Amps

you need a voltage drop of 5-3.2 = 1.8v and the amps is about 18ma this
will give you 1.8 = R * 0.018 eg. R = 1.8/0.018 = 100 ohm

q2: i dont understand what you are asking?

/Stig


-----Original Message-----
From: Mike Williams [mailto:mikewilliams3@comcast.net]
Sent: 23. december 2002 19:53
To: simpits-tech@simpits.org
Subject: [simpits-tech] Resistor for LEDs?




Going to be using a PC power supply for my LEDs for my pit, using the 5v
line, what
resistor would I use to bring the voltage and amps down to 3.2v, second
part
of the question, if I feed a terminal strip with the 5v line to feed all
the
lines to the LEDs, (panel backlighting) could I use just one on the
incoming
5v line, or would I use them on all lines from the terminal strip to
each
LED, sorry if this question is simple, I'm just not much of an
electronics
guy.
Thanks

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