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Can you explain? Maybe a YouTube explanation?
I'm new to Arduino but have lots of experience with PLC so I'm trying to mimic the same logic of using relays - maybe this is the solution.
Hey all I'm new to Arduino but have lots of experience in PLC programing, therefore the below scheme will resemble a PLC architecture.
The project is 11 SMDs 0805 20mA LEDs in 4 groups. Each group has its own On/Off toggle switch.
The main goal is to have all LEDs working on demand (all or some) while some are blinking, some are fading in and out and the rest are working on continuously.
I have an Arduino Nano and Uno, 9v (Alkaline) and 12v (LiPo) batteries to use to power all up.
Wiring using 30awg enamel magnet wires - for LEDs.
Green and White LEDs are 3-3.2v while the Red LEDs are 2-2.2v.
My questions are:
Does this project feasible as an Arduino project?
Do I must use resistores for each LED or can I use a volatge stepdown for each group of LEDs with the same voltage input?
I did a test today with 3*10kOhm resistores to reduce 5v,5A to 3v and the White LED wasn't bright enoutgh in comapre to a 3v,5A in direct input (I guess V=IR worked here)
What about current consumption? How can I control it?
Can I combine LEDs with the same working condition or I must use each LED in diffrent digital output?
Which Nano are You using? There might be several different ones. Find out max I/O voltage it has, 3.3 or 5 volt.
You can't use resistors to create controller power. Use a stepdown converter making the Vcc for the controller.
Each LED must have a serie resistor controlling the LED current. If the LED powering voltage is higher than I/O pin max voltage, drivers are needed.
Yes it is feasible.
1 Resistors for each group of series LEDs
1 Resistor for individual LEDs
No parallel LEDs
Check the current ratings of the LEDs, that controls brightness.
A few Hints and Helps:
9V batteries generally do not last long and cannot supply enough power.
LEDs have different forward voltage drops depending on the color.
LEDs will work with a wide range of current, typ. 20ma Max for small ones
Here are some online calculators that will help:
Crispy Critter Rules:
Rule #1. A Power Supply the Arduino is NOT!
Rule #2. Never Connect Anything Inductive to an Arduino!
Violating these rules tends to make crispy critters out of Arduinos.
Each LED needs its own resistor to control the current. Use each LED's forward voltage specification to determine the resistor for the current you want.
Modern LEDs can be bright at very small currents. Try 5, 10 and 20 mA to see how your LEDs look. Most can tolerate 20 mA, but check that before seeing if.
You can attach several at one output pin.
But you must not exceed the maximum allowed current on the pin, or the port the pin is part of, or the microprocessor chip itslef, three different current limits.
If you need more current, a simple transistor or MOSFET circuit can control all the power you need, just don't draw that power off the Arduino board.
Thanks!
There is any way I can use Arduino as a PLC?
Meaning to control a set of relays while the current is drawn from an external source (not from the Arduino board) and the arduino is only the "brain" with gives the relay the command to close or open its contactors.
I really don't have any experience with electronics such MOSFETs and resistors.. the maximum is to solder and build drones electronics.. not to design the circuits.
If you can make a quick diagram of your idea of how I can control all the LEDs in the diagram in my original post it will be a huge help!
Sketch your LED's, group them and post them, then we can get into the circuit. You can put them in series but they will all light at the same time, this would require 1 resistor per led string. Add up the Vf of each led in the string, subtract that from your supply voltage, then use OHM's calculator and determine the resistor value. As long as the current is below 20 mA you will be OK. The resistor value will determine the current and the brightness. The higher the brightness the dimmer the LED. Individual controllable LED's need to each have its own resistor as shown by alto777.
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