Office stop light

Office Busy Signal Stoplight

Since I’m working from home these days, because of COVID-19 and social distancing to flatten the curve, I decided to clean my office. When I clean/organize I end up getting rid of a bunch of stuff I haven’t used in years. I also sometime find small treasures.

In one of the random-stuff boxes I found my Dad’s original office stoplight that he used when I was a kid. Essentially, it’s miniature stoplight that was used to indicate my Dad’s availability at any given moment. It was made with incandescent light fixtures with colored light covers. The light were controlled by two toggle switches.

Since my kids are home from school too, for the same reason I’m working from home, I thought this would be a perfect opportunity to give this stoplight box new life. Hopefully it will help the kids let me be when I’m in the middle of something.

While I could have made this from scratch that would have a much smaller profile, I wanted to keep the original look. I did replace the 6V incandescent light bulbs with colored LED’s. This was simple enough to do by cutting the light bulb fixture in half on the bandsaw. Then it was as simple as wiring up the LED’s and programming the ESP8266 thing with a very simple web interface.

Parts list:

  • Red LED
  • Yellow LED
  • Green LED
  • 220Ω resistor
  • Sparkfun ESP8266 thing
  • USB Cable
  • USB power adapter


 *  Simple web LED control for a stop light.
 *  The server IP address of the ESP8266 module, will be printed to Serial when the module is connected.

#include <ESP8266WiFi.h>
#include <WiFiClient.h> 
#include <ESP8266WebServer.h>

// WiFi Definitions //
const char *ssid = "your_wifi";
const char *password = "your_password";
const char *hostname = "office-stop-light";
const String title = "OFFICE STOP LIGHT CONTROL";

// Pin Definitions //
const int RED_LED_PIN = 4;
const int YEL_LED_PIN = 0;
const int GRN_LED_PIN = 5; // Thing's onboard, green LED

// Create an instance of the server
// specify the port to listen on as an argument
ESP8266WebServer server(80);

/* Homepage Webcode */
void send_homepage() {
  String server_index = "<!DOCTYPE html><html lang=\"en\"><head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1, user-scalable=no\"/><title>"+title+"</title>";
  server_index += "<style>.c{text-align: center;} div,input{padding:5px;font-size:1em;}  input{width:90%;}  body{text-align: center;font-family:verdana;} button{border:0;border-radius:0.6rem;background-color:#1fb3ec;color:#fdd;line-height:2.4rem;font-size:1.2rem;width:100%;} .q{float: right;width: 64px;text-align: right;} .button_blue {background-color: #008CBA;} .button_red {background-color: #f44336;} .button_yellow {background-color: #ffdd00; color: black;} .button_dark_grey {background-color: #555555;} .button_green {background-color: #4CAF50;} </style>";
  server_index += "<script>function c(l){document.getElementById('s').value=l.innerText||l.textContent;document.getElementById('p').focus();}</script>";
  server_index += "</head><body><div style='text-align:left;display:inline-block;min-width:260px;'>";
  server_index += "<H3>"+title+"</H3>";
  server_index += "<form action=\"/cmd_red_on\" method=\"get\"><button class=\"button_red\">Red</button></form><br/><form action=\"/cmd_yellow_on\" method=\"get\"><button class=\"button_yellow\">Yellow</button></form><br/> <form action=\"/cmd_green_on\" method=\"get\"><button class=\"button_green\">Green</button></form><br/><form action=\"/cmd_all_off\" method=\"get\"><button class=\"button_dark_grey\">Off</button></form><br/>    ";
  server.send(200, "text/html", server_index);

/* Go to http://office-stop-light in a web browser with a device on the same network as this ESP8266 thing. */
void handleRoot() {

void cmd_red_on() {
  digitalWrite(RED_LED_PIN, 1);
  digitalWrite(YEL_LED_PIN, 0);
  digitalWrite(GRN_LED_PIN, 0);

void cmd_yellow_on() {
  digitalWrite(RED_LED_PIN, 0);
  digitalWrite(YEL_LED_PIN, 1);
  digitalWrite(GRN_LED_PIN, 0);

void cmd_green_on() {
  digitalWrite(RED_LED_PIN, 0);
  digitalWrite(YEL_LED_PIN, 0);
  digitalWrite(GRN_LED_PIN, 1);

void cmd_all_off() {
  digitalWrite(RED_LED_PIN, 0);
  digitalWrite(YEL_LED_PIN, 0);
  digitalWrite(GRN_LED_PIN, 0);

void setup() {

  // prepare GPIO / LED
  digitalWrite(RED_LED_PIN, 0);
  digitalWrite(YEL_LED_PIN, 0);
  digitalWrite(GRN_LED_PIN, 0);
  // Connect to WiFi network
  Serial.print("Connecting to ");

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
  Serial.println("WiFi connected");
  // Configure and start the server
  server.on("/", handleRoot);
  server.on("/cmd_red_on", cmd_red_on);
  server.on("/cmd_yellow_on", cmd_yellow_on);
  server.on("/cmd_green_on", cmd_green_on);
  server.on("/cmd_all_off", cmd_all_off);
  //get heap status, analog input value and all GPIO statuses in one json call
  server.on("/all.json", HTTP_GET, []() {
    String json = "{";
    json += "\"heap\":" + String(ESP.getFreeHeap());
    json += ", \"analog\":" + String(analogRead(A0));
    json += ", \"gpio\":" + String((uint32_t)(((GPI | GPO) & 0xFFFF) | ((GP16I & 0x01) << 16)));
    json += "}";
    server.send(200, "text/json", json);
    json = String();
  Serial.println("Server started");

  // Print the IP address

void loop() {

Wiring Diagram

Web Interface

Smart Chicken Coop Light

When we first got chickens, we were trying all kinds of things we read online to get the most out of our laying hens. This project was one of those silly ideas to try and provide more “daylight” for the chickens year round, so they would lay eggs year round.

I through this together on a weekend. With these basic features in mind:

  • On and off schedule
  • Dimmable
  • Log temperature and Humidity
  • Battery Powered

I used the following parts to make it happen (mostly because I already had them available):

I’m not going to go into a detailed step by step process on how I put this together, but hopefully between the pictures and description you can get the idea.

I followed these general steps to assemble the hardware:

  1. Layout placement of parts in the lights
  2. Modify light fixture
    • Cut out battery holder
    • Join the two light together
    • Drill out holes for charge port, and mounting points
  3. Wire components and fit into lights
    • Solder the JST Jumper wire to the battery so it can be plugged straight into the Blynk board
    • Wire the MOSFET Source -> GND, LED Cathode -> MOSFET Drain, LED Anode -> Vin, MOSFET Gate -> Pin 5. (Circuit Demo)
    • Wire temperature sensor to the ADC pin
  4. Test, rinse, repeat
  5. Semi-permanently mount board and battery
  6. Close it all up and test

Arduino sketch and Blynk app source:

Mini Iron Man Arc Reactor

This was a costume prop my brother and I made for our nephew Carter.

Nothing special, just soldered a ring of white LED lights into a transparent 3D printed ring, and powered it all with a couple coin cells. Somehow we missed an LED and couldn’t get it working. And since we welded the LEDs between the ABS printed parts. We would have to destroy it and start over to try and fix it.

I wish I had taken more pictures early during the build.

Toothless Wings

Nothing much to this costume. I just cut up a black fleece blanket into the general shape of toothless wings. Then used a sowing machine to sow the ridges.

I was very lazy with the lights. I hot-glued some RGB LED strips to the wings, one on each side of the center ridge. Then wired the blue lights to a 9V battery plug. Then hot glued a Velcro cable tie to the back side of the wings to hold the 9V battery.

LED Desk Lamp Hack

Here you can see all the components used in the lamp. It originally used E14 small screw 40w incandescent bulb. And has been modified to use 8 bright white LEDs.

The circuit is pretty simple. I’m using the innards of a 120V AC to 6V DC transformer in series with an 8.2 ohm resistor to power the LEDs. The original 120V AC power cord and switch is soldered onto the 120 V input of the transformer. 
Then I made my own LED grid using 4 white LED pairs in parallel. Then soldered some long wires to feed down through the tube to the transformer. And finally, soldering the LEDs and the 8.2 ohm resistor to the 6V DC output on the transformer.

I used a water bottle lid to separate the LED grid from the metal arm that used to hold the old bulb. This is to ensure nothing would short out.

The final result is a nice warm white light that is just right for illuminating my desk.

NOTE: I had all of this stuff laying around I thought I’d put them to good use. It really isn’t necessary to use a 10W 8.2 ohm resistor.

UPDATE: I’ve since replaced the internal electronics with just a 5V 400ma 120VAC tranformer with no resistor. While it worked before, It was a little too dim for use at my workbench.