I am very new to this forum and I only found out about Arduino recently. I want to control an Arduino board with my computer (via USB). When dictated by the computer, I want the Arduino board to illuminate a lamp (several lamps actually but only one at a time).
My questions are:
Does the power for the lamp come from the 5v power in USB cable?
If so, then I assume I am limited to a lamp that can be powered by 5 volts. True?
If true, what is the brightest lamp I can illuminate?
Are there other sources of power I can “plug-in” to the Arduino, 12 volt DC for example, that will allow me to control the illumination of an automotive brake light? (which would be bright enough for what I need).
Thanks so much for any feedback you can provide. This is all very exciting for me!
The short answer is that you should not use an Arduino to power lighting (or motors, or any other significant loads). (It’s OK to use it to power small LEDs as indicators.)
For what I understand you’re trying to do, you should use the Arduino to send control signals to switches which will control the power for lighting.
For example, you could use one of [these to switch six 12 V circuits. (You should read the comments on that page, not just the description. The description directs you to the datasheet for the transistors to determine permissible current, but that’s very bad advice! SparkFun designed the board to be capable of much less current than the transistors themselves can handle. :roll:
Is there some reason to use automotive brake lights, or any incandescent light? If you use LEDs, you can get much more light and much less heat for the same amount of electrical input (or as much light and much, much less heat for less electrical input) and be able to have the Arduino set the brightness by PWM modulating the power. (You can PWM modulate the power to an incandescent bulb, but its color changes substantially with dimming.)
Thanks for the link to the switches. That makes sense.
I would be happy to use LEDs. I only mention automotive brake lights to give you an idea of the brightness I require. Perhaps I can get similar brightness from an LED and power them directly off the Arduino board. What do you think? I will only have a single LED illuminate at any one time. What is the brightest LED I could power directly from the Arduino board and is there any way you can compare its brightness to that of an automotive brake light. I only use that as a comparison because I have a feel for how bright it is.
Blinky:
What is the brightest LED I could power directly from the Arduino board
You need to go look up the maximum current for a DO pin on the Arduino ([Start here.), then find some LED datasheets and figure out which one is most to your liking in color and light power that does not exceed the Arduino’s current limit.
Blinky:
and is there any way you can compare its brightness to that of an automotive brake light. I only use that as a comparison because I have a feel for how bright it is.
SparkFun designed the board to be capable of much less current than the transistors themselves can handle. :roll: