Category Archives: Projects

How To Build An Arduino Love Tester

I’m a bit of a sucker for retro electronic novelties, and one of the most prolific is the “love tester” device that–in various forms–hearkens back to the early 20th century and the heyday of the penny arcade. These were often an electromechanical device that used some algorithm (or even just a random number generator) to ring bells, flash lights, and indicate either a fortune or–more often–a rating of one’s romantic prowess. In the 1960s, Nintendo released their first (in what would prove to be quite a long line) of electronic toys which gave a love rating based on the electrodermal activity between two people. In this video, part of a series building a project for element14 Presents, I’ll walk through using an Arduino to replicate the Nintendo Love Tester so you can build your own meter for your Valentine.

Get the Arduino code, bill of materials, and more on

Check out the rest of Project Eros here

Arduino Basics Lesson 2-2: An Energy Conversion Unit

For the “Arduino For Kooks” course, I recommend you get the Arduino Starter Kit available here.

Building on our last project, we’re going to find a new way to control our piezo buzzer. Rather than using buttons, we’re going to use the variable resistance of a photoresistor to create different tones–a sort of light-activated Theremin. A photoresistor is an element that changes resistance based on the amount of light it detects. The more light, the less resistance. This device will convert those resistance values into various tones for our Theremin.

The Circuit:

Connect a jumper wire from +5V and GND to their respective busses on the breadboard. Connect a jumper from the +5V bus rail to one side of the photoresistor. This part is not polarized, so it doesn’t matter which side. Connect the opposite side of the photoresistor to GND via a 10K resistor and to A0 via another jumper.

Connect D8 to the positive leg of the piezo via a jumper and connect the ground leg of the piezo to GND.The Sketch:

int sensorValue;
// variable to calibrate low value
int sensorLow = 1023;
// variable to calibrate high value
int sensorHigh = 0;
// LED pin
const int ledPin = 13;

void setup() {
// Make the LED pin an output and turn it on
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, HIGH);
// calibrate for the first five seconds after program runs
while (millis() < 5000) { // save the maximum sensor value sensorValue = analogRead(A0); if (sensorValue > sensorHigh) {
sensorHigh = sensorValue;
// save the minimum sensor value
if (sensorValue < sensorLow) {
sensorLow = sensorValue;
//turn the LED off, signaling the end of the calibration
digitalWrite(ledPin, LOW);

void loop() {
//read the input from A0 and store it in a variable
// map the sensor values to a wide range of pitches
int pitch=map(sensorValue, sensorLow, sensorHigh, 50, 4000);
// play the tone for 20 ms on pin 8
tone(8, pitch, 20);
// wait for 10ms

The Elegoo Smart Robot Car Kit 3.0

Elegoo, a manufacturer of Arduino-clone electronics and kits based in Shenzhen, China, approached me to do review their new Arduino-powered Smart Robot Car Kit. It’s a neat little kit–something fun to put together on a weekend and mess around with.

As for the meat-and-potatoes, it’s got a few bugs to work out. The car runs great with the included IR remote control, and can easily be programmed to use various sensors or just traverse pre-programmed missions (a la the classic Big Trak toy from Milton Bradley). The ultrasonic obstacle detection/avoidance mode also works like a champ. However, I couldn’t get the Bluetooth functionality working. It may be that the included Bluetooth module is not compatible with the latest versions of Android (as my cursory research and troubleshooting has led me to believe) due to updates in security protocols with Oreo and Pie. Your mileage may vary, though. Also of note was the line-tracking module which had a faulty LED and would only allow the car to spin in circles.


My contact at Elegoo was polite and provided me with some generic troubleshooting information, but they were unwilling to replace the faulty parts. If they’re not going to do it for the review, I would assume that they would be unwilling to do it for the consumer as well, so please take note. That being said, this is the first time that I have had as much trouble with an Elegoo-branded product, as I have used their Arduino clones and passive components in the past with no issue. I hope that this experience was a fluke, but only time will tell. I do want to emphasize that these sorts of problems can and do happen with any distributor, so it is not a mark against their quality per se.

At the end of the day, I’ll likely use these parts for some other projects (the geared motors and control boards may come in quite handy later), and have no real qualms about purchasing through Amazon as you’re protected by their returns policy (provided you purchase from the listing “fulfilled by Amazon”). So, give it a try. It’s a lot of fun to build, and makes a great transition from static Lego kits to full-fledged electronics hackery!

The Elegoo Smart Robot Car Kit 3.0 is available from Amazon

Music by Anders Enger Jensen

Project Rankin: A Retro-Commercial Holiday Ornament

A child of the hyper-consumerist 80s and 90s, Matt grew up on a steady diet of sugared cereal and UHF television. As such, his sense of nostalgia is driven as much by advertising trends of the era as it is by music or other sociological elements. This leads to an interesting relationship with the winter holiday season, where seasonally-themed television commercials hold as high a place in tradition as any carol, tree, or gift exchange. To celebrate this odd bit of seasonal nostalgia, Matt builds a retro-television-themed ornament from a Raspberry Pi that plays those magical commercials from his youth and is powered by a strand of holiday fairy lights!

Engage with the element14 presents team on the element14 Community – suggest builds, find project files and behind the scenes video:

Arduino Basics Lesson 2-1: “Play It Again, Sam”

For the “Arduino For Kooks” course, I recommend you get the Arduino Starter Kit available here.

Up until this point in the series, we have been using LEDs to manipulate light with the Arduino. For this project, we’re going to incorporate a piezo buzzer to manipulate sound for Maximum Annoyance Value! The piezo is a small element that vibrates in the presence of an electric current or–alternatively–generates an electric current when it vibrates.

The Circuit:

Connect jumper wires from the +5V and GND pins on the Arduino to the bus rails along one side of the breadboard. Connect a jumper from the +5V rail to one side of a tactile switch. Connect the other side of the switch with a jumper to one side of the next switch, and so on, until you have wired all 4 switches in series. Connect a jumper from the last switch terminal to pin A0 on the Arduino.

Connect the 220R, 1KR, and 1MR resistors to the switches as shown in the diagram.

Connect the ground lead of the piezo buzzer to the ground rail and the positive lead to pin 8 on the Arduino via jumper wires.

The Sketch:

  Play It Again, Sam
A rudimentary Arduino synthesizer

  created 13 Sep 2012
  by Scott Fitzgerald

  This example code is part of the public domain.

// create an array of notes
// the numbers below correspond to the frequencies of middle C, D, E, and F
int notes[] = {262, 294, 330, 349};

void setup() {
  //start serial communication

void loop() {
  // create a local variable to hold the input on pin A0
  int keyVal = analogRead(A0);
  // send the value from A0 to the Serial Monitor

  // play the note corresponding to each value on A0
  if (keyVal == 1023) {
    // play the first frequency in the array on pin 8
    tone(8, notes[0]);
  } else if (keyVal >= 990 && keyVal <= 1010) { // play the second frequency in the array on pin 8 tone(8, notes[1]); } else if (keyVal >= 505 && keyVal <= 515) { // play the third frequency in the array on pin 8 tone(8, notes[2]); } else if (keyVal >= 5 && keyVal <= 10) {
    // play the fourth frequency in the array on pin 8
    tone(8, notes[3]);
  } else {
    // if the value is out of range, play no tone

Commodore SX-64 1541 Floppy Drive Repair

The Commodore 1541 floppy diskette drive is notorious for breaking down. The Commodore SX-64 floppy drive is no different. As I continue my Commodore SX-64 restoration, I find that the 1541 floppy drive doesn’t read diskettes any more and makes a chattering sound when attempting to read a disk. In this video, I walk through how to diagnose the SX-64 floppy drive as well as possible remedies before finally replacing the 1541 mechanism with a standalone drive.

Commodore SX-64 Keyboard Repair

The Commodore SX-64 keyboard is usually the first thing to fail on these old systems. As such, I need to repair the keyboard on this SX-64 restoration. To begin, I’ll need to DIY an SX-64 keyboard cable from a 25-pin serial cable. I’ll use the SX-64 replacement keyboard cable to diagnose problems with the membrane keyboard itself and resurface the SX-64 membrane keyboard. Finally, I’ll rebuild the plastic shell of the SX-64 keyboard with Bondo automotive filler in order to get the SX-64 keyboard as close to the original stock look as possible.

Commodore SX-64 Blank Screen Fix

In my quest to restore the Commodore SX-64, my first obstacle was the lack of video signal on the internal monitor. I needed to diagnose the Commodore SX-64 video signal before I would be able to move on to any other Commodore SX-64 repairs. In this video, I will go through the process to diagnose a Commodore SX-64 blank screen and step through how to repair a Commodore SX-64 blank screen. In this video, I’ll go over how to build a DIY Commodore AV cable, how to reseat Commodore chips, and how to replace a Commodore PLA chip.

Check out more Commodore SX-64 videos here

Watch the complete Commodore SX-64 restoration here

How To DIY Commodore 64 AV Cable

I was having a little trouble working on my Commodore SX-64, trying to diagnose a blank screen, so I needed to attach the Commodore 64 to a TV. Unfortunately, with these retro computers, the cables seem to vanish into the dustbin of history. So, to fix my borked Commodore SX-64, I needed to hack together a DIY Commodore AV cable. This 5-pin DIN AV cable is compatible with all Commodore models as well as the Atari 800 series and TI-99/4 among others! This video will show you how to DIY a Commodore 64 AV cable with just a few commonly-available components!

Check out more Commodore SX-64 videos here

Watch the complete Commodore SX-64 restoration here

Music by EOX Studios

“Pausesignal NRK” by Anders Enger Jensen Used with permission, available from or on SoundCloud

Jon’s Crazy Commodore SX-64 (Retro Tech Rogue Trip 01)

My friend Jon Esparza (@jonscrazytweets) discovered a rare Commodore SX-64 while going through his late father’s storage unit. Knowing that I was a retro computer enthusiast, he gave me a call to see if I was interested in doing something with it. So of course I took a road trip to south San Diego to see this “Commodore laptop” in person (and get some bomb tacos)! Jon was kind enough to let me take this Commodore SX-64 off his hands and see if I could get it in any better shape than it’s currently in. This is going to be a rough Commodore restoration, so be sure to stay tuned for the next installment!

Check out more Commodore SX-64 videos here

Watch the complete Commodore SX-64 restoration here

Check out Jon’s Crazy Stuff:

Music by EOX Studios “You On The Dance Floor” by Silverimage “Space Traveler” by Anders Enger Jensen Used with permission, available from or on SoundCloud