NotLikeALeafOnTheWind

Impressive, indeed.

Sure, you can do it with a single led. You simply have to PWM the output of the led to control the brightness. Here is a very simple program that will demonstrate the effect you are trying to achieve. This is set up for an Arduino Nano and a three buttons. /* Button test V2 Demonstrate using pwm to dim an arcade button. The button will be on with low intensity untill pressed. */// Set pin numbers:const int buttonpin1 = 5; // the number of the pushbutton pinconst int buttonpin2 = 6;const int buttonpin3 = 7;const int ledPin1 = 11; // the number of the LED pinconst int ledPin2 = 12;const int ledPin3 = 13;const int pwmvalue = 25; // set to an aproprate number to dim the led in the button void setup() { // initialize the LED pin as an output: pinMode(ledPin1, OUTPUT); pin…

Sure, you can do it with a single led. You simply have to PWM the output of the led to control the brightness. Here is a very simple program that will demonstrate the effect you are trying to achieve. This is set up for an Arduino Nano and a three buttons. /* Button test V2 Demonstrate using pwm to dim an arcade button. The button will be on with low intensity untill pressed. */// Set pin numbers:const int buttonpin1 = 5; // the number of the pushbutton pinconst int buttonpin2 = 6;const int buttonpin3 = 7;const int ledPin1 = 11; // the number of the LED pinconst int ledPin2 = 12;const int ledPin3 = 13;const int pwmvalue = 25; // set to an aproprate number to dim the led in the button void setup() { // initialize the LED pin as an output: pinMode(ledPin1, OUTPUT); pinMode(ledPin2, OUTPUT); pinMode(ledPin3, OUTPUT); // initialize the pushbutton pin as an input: pinMode(buttonpin1, INPUT_PULLUP); pinMode(buttonpin2, INPUT_PULLUP); pinMode(buttonpin3, INPUT_PULLUP); analogWrite(ledPin1, pwmvalue); analogWrite(ledPin2, pwmvalue); analogWrite(ledPin3, pwmvalue); Serial.begin(115200); Serial.println("start");}void loop() { // check for button 1 press if (digitalRead(buttonpin1) == LOW) { // turn LED 1 on: digitalWrite(ledPin1, HIGH); Serial.println("Button 1 is pushed"); } else { analogWrite(ledPin1, pwmvalue); } // check for button 2 press if (digitalRead(buttonpin2) == LOW) { // turn LED 2 on: digitalWrite(ledPin2, HIGH); Serial.println("Button 2 is pushed"); } else { analogWrite(ledPin2, pwmvalue); } // check for button 3 press if (digitalRead(buttonpin3) == LOW) { // turn LED 3 on: digitalWrite(ledPin3, HIGH); Serial.println("Button 3 is pushed"); } else { analogWrite(ledPin3, pwmvalue); }}

Direct from Adafruit. They were back in stock this morning.

No, I haven’t, but thanks. It is an interesting idea that I am going to try. I see Adafruit has a product (https://www.adafruit.com/product/4749 ) and Amazon has ( https://www.amazon.com/Rock-Hard-Plastics-Acrylic-Plexiglass/dp/B082ZBL1XR/ ). Would you care to make other recommendations? Is there a range of opaqueness that is optimal?

Please check my math.DC amps to watts P(W) = I(A)× V(V)Where:P is Power in wattsI is Current in ampsV is DC Voltsin voltsSo 80 amps x 5 volts = 400 wattsLet’s walk through the power supply sizing calculation. Now according to the manufactures data sheets for a 64 x 32 RGB LED matrix panel the maximum current draw for current for all LEDs illuminated is ~4A and for a 64 x 64 panel is ~5 amps. My measured values are less than this but we will use the data sheets for this calculation. The two largest displays we have constructed using this method are a 4 by 4 matrix and (2) 4x2 matrix in a single frame. The 4 by 4 matrix uses 64 x 64 panels and the other used 64 x 64 panels. This gives us:16 x 5 amps = 80 amps and 16 x 4 amps = 64 amps potential maxim draw. Applying the safety factor( 20%) …

Please check my math.DC amps to watts P(W) = I(A)× V(V)Where:P is Power in wattsI is Current in ampsV is DC Voltsin voltsSo 80 amps x 5 volts = 400 wattsLet’s walk through the power supply sizing calculation. Now according to the manufactures data sheets for a 64 x 32 RGB LED matrix panel the maximum current draw for current for all LEDs illuminated is ~4A and for a 64 x 64 panel is ~5 amps. My measured values are less than this but we will use the data sheets for this calculation. The two largest displays we have constructed using this method are a 4 by 4 matrix and (2) 4x2 matrix in a single frame. The 4 by 4 matrix uses 64 x 64 panels and the other used 64 x 64 panels. This gives us:16 x 5 amps = 80 amps and 16 x 4 amps = 64 amps potential maxim draw. Applying the safety factor( 20%) gives :80 amps * 1.2 = 96.0 amps rounded up gives us 100 amps64 amps * 1.2 = 76.8 amps rounded up gives us 80 ampsAgain this is how we do our sizing calculation. You may have a different methodology based on your needs. I do agree with you that I should have said the biggest display we built for home was 128 x 128, which as true when most of this was written. The takeaway should be watch the wire sizes and layout of your power distribution. This page covers in much more detail. https://github.com/hzeller/rpi-rgb-led-matrix/blob/master/wiring.md

The blade has held up nicely for what we use it for, cutting aluminum and aluminum profiles. The current blade was purchased in January of 2014. It is only used to do a couple hundred cuts a year so it really does not have a lot of time on it.

Can you share the data sheet or the source of your LEDs? Looking at the pictures, they appear to be UVA 400nm Purple LED 5mm Clear Len LEDs. If this is true, then they produce UV-A. When most people think about the UV disinfectant properties of light they are talking about UV-C. A great place to start is: https://iuva.org/IUVA-Fact-Sheet-on-UV-Disinfection-for-COVID-19 or https://www.waveformlighting.com/uv-c-led/what-is-the-difference-between-uv-a-and-uv-cWhat you have built is a nice UV-A (blacklight) flashlight. It will make things glow, but I would be extremely cautious about making clams of sanitizing properties.

Cool, Thank you for the information. You might want to take a look at: https://www.instructables.com/A-complete-STEM-Curriculum-For-37-Cents-Per-Studen/ They use a similar LED. There is a nice discussion of the physics, safety and germicidal properties of this (and all uv-a) LEDs. The executive summary is they are not "virus killers."

What kind of glass did you use to protect the lower LED's? I was under the impression that regular glass blocks UV-C.