Quick concern

Using Arduino General Electronics
1

Hello,

I have two things I want to quickly ask, but let me preface this by saying that I am infact new to the Arduino board and micro controllers. So my questions are:

  1. Is it harmful for me to run multiple LED's from one pin on a breadboard? For example, I want 4 LED's to turn on simultaneously, so the need for individual control is unnecessary, so I wired my first LED to pin 13 on my breadboard with a 330 resistor on the cathode, and then ran 3 more wires from that same breadboard row, so a to provide 3 other LED's with power as I do the same for the first LED that I wired to pin 13. Yes I see that it does light up all 4 LED's but my question is it harmful for the LED's to do this? all 4 are on 330 ohm resistors.

  2. This is a matter of suggestion perhaps. For the project I'm working on I need some way to electronically lock a box using my Arduino. My original thoughts were to use a servo to push or pull a pin through a loop connected to the lid. So that when the pin was pushed in the loop the lid could not open until a button is pushed and the pin was pulled back out. My father's suggestion though, who is helping me with the woodworking of this project, suggested using an actuator instead? Which from what I understand is basically the pin built into the electronics? So my question is, should I use a servo/actuator/ or something else? and if an actuator is indeed the route to go, does anyone know of one I could get that would work with my Arduino Uno quite easily?

Thanks for the help,
-DevenJ

2

DevenJ:
Hello,

I have two things I want to quickly ask, but let me preface this by saying that I am infact new to the Arduino board and micro controllers. So my questions are:

  1. Is it harmful for me to run multiple LED's from one pin on a breadboard? For example, I want 4 LED's to turn on simultaneously, so the need for individual control is unnecessary, so I wired my first LED to pin 13 on my breadboard with a 330 resistor on the cathode, and then ran 3 more wires from that same breadboard row, so a to provide 3 other LED's with power as I do the same for the first LED that I wired to pin 13. Yes I see that it does light up all 4 LED's but my question is it harmful for the LED's to do this? all 4 are on 330 ohm resistors.

You need to keep track of the total pin current being consumed by all the leds wired to a single pin and try and keep the total under 30ma or so (40ma is absolute max limit) or output pin damage can result. The on board led consumes about 4ma, your additional leds each with 330 ohm resistor consume about 10ma each, so total of 4 external + on board approches 44ma which is exceeding the manufactures specification. That is assuming red leds with 1.5vdc forward voltage drop, other leds have higher voltage drop which should lower the current consumtion some. Learn to do the math and keep pin current below manufacture's specifications and you should be OK.

  1. This is a matter of suggestion perhaps. For the project I'm working on I need some way to electronically lock a box using my Arduino. My original thoughts were to use a servo to push or pull a pin through a loop connected to the lid. So that when the pin was pushed in the loop the lid could not open until a button is pushed and the pin was pulled back out. My father's suggestion though, who is helping me with the woodworking of this project, suggested using an actuator instead? Which from what I understand is basically the pin built into the electronics? So my question is, should I use a servo/actuator/ or something else? and if an actuator is indeed the route to go, does anyone know of one I could get that would work with my Arduino Uno quite easily?

By actuator I assume you might mean a solenoid with is a spring loaded magnetic actuator. While solenoids are useful for your application they tend to be hard to find in 5vdc versions, most are 12v or 24v. So depending on how you are going to power your 'box' would make it easier to decide if a servo or solenoid would interface better. If you go with the servo get the smallest micro size version you can find so that it's current draw is more inline with what can be powered directly from a arduino board due to it's current capacity limitation.

http://cgi.ebay.com/2-5g-micro-servo-Plastic-Gear-SD25-/180637375488?pt=LH_DefaultDomain_0&hash=item2a0ed39c00

Lefty

Thanks for the help,
-DevenJ