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Topic: need to know what resistor to use for my project (Read 1 time) previous topic - next topic


I'm a total newbie.  I just bought the Arduino Uno board and I bought Radio Shack's Sidekick Basic Kit for Arduino.    I'm trying to do a project I found in a book.  It calls for 100 ohm resistor.  I have 3 types of resistors marked 1)1k Ohm Resistor , 2)10K Ohm Resistors  and 3) 330 Ohm Resitors.  I think  I should us e the 330 Ohm but I'm not sure and I don't want to brake anything before I even get started!!!! 

Jack Christensen

I might go back to RS and get some 100 ohm resistors.

My crystal ball is in the shop, so I can't comment on whether a 330 ohm resistor would work, without seeing the project (hint: got a link?)

If you have three 330-ohm resistors, put them in parallel, that will give 110 ohms.
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/


Thanks.  (Can't go to RS now- a blizzard on US EAST COAST!)
  The project is a simple led flasher. From book "beginning arduino "
The hardware used in Project 1:


5mm LED

100 ohm Resistor*

Jumper Wires

* or whatever value appropriate for your LED

The code is:

Listing 2-1. Code for Project 1

// Project 1 - LED Flasher
int ledPin = 10;
void setup() {
         pinMode(ledPin, OUTPUT);
void loop() {
        digitalWrite(ledPin, HIGH);
        digitalWrite(ledPin, LOW);

Jack Christensen

Oh, OK, 330 will be fine. It's a current-limiting resistor for the LED. With 330 it might not be as bright, but actually 330 is sort of my "standard" resistor for most 5mm LEDs, many of them are quite bright with 330 ohms at 5V.

Good luck digging out. The storm has moved out here, it will be a cold and clear night with lows around 5°F. We had maybe 4" or 5" of snow, so nothing all that remarkable here.

Good weather to stay in and play with microcontrollers, enjoy!
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Nick Gammon

As Jack said, 330 ohms would (probably) let 10 mA flow through your LED, which should be plenty to make it light up nicely. Have fun playing with it. :)

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