I'll be honest and say I can't remember why I thought of this, but is there a simple way to have the Arduino output power and nothing else?
Also, I am completely new to Arduino/electronics etc, but if this does work, the flow of how things work is (in the case of Arduino) 5v Pin --> components on breadboard --> Ground, right?
It is also possible to wire...Arduino Pin --> components on breadboard --> 5VThe keyword in this case is "sink"; as in the pin "sinks" five volts or "sinks" 20 milliamperes. The logic is reversed. This allows current to flow through the components... digitalWrite( 7, LOW );
My (3rd?) question is this: The way I understand resistors (in this case specifically with LEDs, though I'm sure it applies elsewhere) is that resistors should be between the source and the anode. Is this always true (or am I completely wrong) in thinking this? The reason I ask is that occasionally when looking at schematics and diagrams it appears that the resistors are placed between cathode and ground.Logically that doesn't seem right, and I don't see it often, but I have seen it.My guess is that the true answer is far more complicared than I'm ready for.
Thus 20mA should be consired the max current for guaranteed voltage levels and reliable long term operation.
Functional operation of the device at these or other conditions beyond those indicated in the operational sections of this specification is notimplied.
There are 2 VCC, 2 GND pins each with absolute max of 200mA. The limit of 300 is well below the 400mA absolute max.
As an electrical engineer, I interpret the data sheet to say that if one sources more than 20mA with VCC=5V, the output will <=4.2V and likely decreasing, and if one sinks more than 20mA with VCC=5V the output will be >=0.9V and likely increasing.
I hope my replies here don't come across as argumentative
I know that your advice is based on sound manufacturing principles.
But we are not talking about designing products here. Arduino is about tinkering. If a project needs to drive a couple of LEDs at 40ma then why not?