leds on Bald Engineer

6 Simple Mistakes Electronics Beginners Make

Mon, 30 Jun 2014 14:00:47 +0000

Sometimes the hardest lessons are the ones you have to learn multiple times. When getting started with Electronics circuits, there’s a handful of things that can ruin a day (or experiment.) Here are 6 mistakes I made when I got started, and mistakes I see in the beginner classes I teach. In fairness #6 isn’t one I did starting out, because Fritzing wasn’t around. However, it took me a while to learn the value of providing a schematic, even a simple sketched out block diagram.

AddOhms: Questions and Answers #1

Fri, 14 Mar 2014 02:00:31 +0000

In the past couple of months, AddOhms has caught a little bit of a following. Nearly every day I have new questions coming my way. I decided to it was time to address a couple of really good questions in a video response. Ironically, in the video I mentioned giving “behind the scenes” info with each video. However, for this one, I don’t really have any. I can say that the next video is going to be on transistors…

AddOhms #8: LEDs and Current Limiting Resistors

Mon, 10 Feb 2014 12:00:49 +0000

The idea for AddOhms #8 has been around for quite some time. I’m always trying to find ways to explain why current limiting resistors are necessary. So while working in the shop one day, I decided to play with some LEDs and a bench-power supply. Then I decided to record what happens.

Arduino Example: Police Lights with millis()

Sat, 28 Jul 2012 18:00:20 +0000

Based on a question from Andrew on the initial Multitasking with millis() tutorial, this example shows how to create a Police-Light like strobe effect. The following code uses no calls to delay(). Code also available via Pastebin.org. // English for which LED to Strobe #define RED 0x0 #define BLUE 0x1 // Variable to track which LED is on byte whichLED = RED; // Where are the LEDs connected? const int LED_Red = 7; const int LED_Blue = 11; // State variables for the LEDs byte Red_State = LOW; byte Blue_State = LOW; // Some delay values to change flashing behavior unsigned long switchDelay = 250; unsigned long strobeDelay = 50; // Seed the initial wait for the strobe effect unsigned long strobeWait = strobeDelay; // Variable to see when we should swtich LEDs unsigned long waitUntilSwitch = switchDelay; // seed initial wait void setup() { pinMode(LED_Red, OUTPUT); pinMode(LED_Blue, OUTPUT); } void loop() { digitalWrite(LED_Red, Red_State); // each iteration of loop() will set the IO pins, digitalWrite(LED_Blue, Blue_State); // even if they don't change, that's okay // Toggle back and forth between the two LEDs if ((millis() - waitUntilSwitch) >= 0) { // time is up! Red_State = LOW; Blue_State = LOW; whichLED = !whichLED; // toggle LED to strobe waitUntilSwitch += switchDelay; } // Create the stobing effect if ((millis() - strobeWait) >=0 ) { if (whichLED == RED) Red_State = !Red_State; if (whichLED == BLUE) Blue_State = !Blue_State; strobeWait += strobeDelay; } } State Variables Red_State and Blue_State Instead of using digitalWrite() directly, “state” variables are used to determine the state (on or off) of each LED. This allows logic inside the loop() to determine when the lights should be turned on or off. Each iteration of loop() will update the LEDs with a digitalWrite() based on this state variable.

MSGEQ7 Simple Spectrum Analyzer

Sat, 07 Jan 2012 08:51:32 +0000

Abstract Mixed Signal Integration has a cool little chip that has 7 built-in bandpass filters. Run an audio signal through it and you have an instant audio spectrum analyzer! This is a simple spectrum analyzer based on an Arduino. Each of the 5 LEDs represent a single section of the chip’s 7 sections of audio spectrum. MSGEQ7 on Adafruit Protoboard Electronics If you want to replicate this setup, here is the hardware you’ll need to get.

LED Tutorial - Learn the basics

Wed, 21 Dec 2011 03:13:39 +0000

Nearly every consumer device makes use of the Light Emitting Diode (LED). This highly versatile device offers an easy way to add an indicator to any project while drawing a relatively small amount of current. Once their operation is understood, adding them to any project is a simple task. This tutorial is a simplified explanation of how a LED works and how to select a current limiting resistor. The LED tutorial here is enough to use LEDs in a project but is not intended to be a thorough explanation.

LED Calculator

Wed, 13 Oct 2010 11:44:05 +0000

Rob ’linear’ Arnold has put together a fantastic LED Series/Parallel Wizard. Not only will it calculate the current limiting resistor you need, it will draw a circuit diagram, and give you full statistics on power usage. If you are just getting started with Electronics, this is a great resource for learning about LEDs. Experienced users will enjoy a quick check of their math. The array above is designed for some Blue LEDs I have laying around. I wanted them to run with 15mA which is well below their max, but still very bright. In this case 1/4W resistors should be fine and each should be 120 ohms. I should be safe hooking this array up to an Arduino since each LED will draw less than each I/O pin can handle AND total current draw is only 60mA.

Matrix LED Shield PCB

Fri, 24 Sep 2010 15:48:25 +0000

The PCB for my very first Arduino shield arrived today from BatchPCB. At first glance everything looks good. The silkscreen with my name and web address didn’t come out so well but that was probably my fault on trying to fit in too much. Looking forward to assembling then with some Blue LEDs!

Row Your Boat, Part 1

Thu, 26 Mar 2009 02:28:39 +0000

This pattern is called Row Your Boat. As one of the strips starts to get brighter, a nearby strip will join in the fading. After completing a fade cycle, they start switching colors. There is a random strobe thrown in there as well. The first 10 seconds are with a diffuser (piece of paper), the last 10 seconds are without. The final panel will use a diffuser. The colors have no correction yet, so red is really dim and green is really bright. It looks like one of the channels of my TLC5940 is going bad. The center LED strip’s blue is very dim. I’m not going to look much into it right now though. Instead, I will wait until I fab a PCB for the 5940 (this weekend?)

LED Strip Fun, First Try

Sun, 01 Mar 2009 15:28:33 +0000

Initially I tried to get a LCD screen working with my Illuminato based Arduino. After a couple of attempts I realized two things: 1. The Iluminato is not ready for prime time. and 2. I burned out the LCD. So I decided to move on to the LCD strips I have from Sparkfun. The program is pretty simple since I am using the PWM outputs. The first video is with the lights off and the second is with the lights on. I need work out the min / avg / max for the different colors. The next step is to create two columns (or rows) of LED strips, using a buffer chip.