LEAP#410 Rube-Goldberg LED Blinking Machine

Here’s a marriage of Homopolar motor and Joule thief that results in a truly impractical Rube-Goldberg mechanism for blinking an LED with a AAA battery. It may be inefficient, but I like it .. mainly because I haven’t seen any quite like this before!

As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub

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LEAP#409 Boldport Bugs: The Conehead

Conocephalus is a genus of bush-crickets, known as coneheads. Now I have one beautifully rendered in a 3D kit from Boldport. It even has a pretty convincing FM-synthesised chirp that varies in response to lighting conditions.

Boldport projects never fail to inspire some new learning. In the case it introduced me to Pure Data - a nifty open source visual programming language for multimedia. I reproduced the Pure Data chirp model and added a few (more...)

LEAP#407 AC-powered DPS3005 Bench Supply

The DPS3005 is one of a range of popular DC power supply modules; this one is designed for up to 32V/5A DC output. For this project, I am mounting the module in a project case, and adding a rectified step-down transformer so the unit is powered from mains AC.

As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub hero_image

LEAP#406 CH340G USB to Serial on a Breadboard

The CH340G is a USB to UART Interface chip. It is often used as a cheap alternative to more established brands. I have some CH340G chips, and with only a few extra components one can build a perfectly serviceable USB to TTL-level serial on a breadboard. I test it out by using it to program an ATmega328 on a breadboard over the serial link.

As always, all notes, schematics and code are in the Little (more...)

mV Meter Battery and Protection Mod

The ATmega328-based millivolt meter based on a design by Scullcom Hobby Electronics has been serving well on my bench. But time for a couple of mods:

  • adding a 9V internal battery that can be used when not connected to external supply - great for when the bench is crowded
  • simple reverse-polarity protection (inline rectifier), particularly to avoid any confusion over centre-negative/centre-positive power connectors

As always, all notes, schematics and code are in the Little Electronics (more...)

LEAP#405 Bootloaders and Arduino Serial Programming

The Arduino IDE makes programming AVR-based microcontrollers so easy that many quite simple concepts get lost in the fog. I confess to having been hazy for the longest time concerning the role of the bootloader and what exactly was going on when you click the “Upload Sketch” button. There are actually some great resources around the net and on YouTube, but they can also mislead a little because they might focus on just one aspect, (more...)

LEAP#404 The Arza-matron

I’ve had the other half of the guitar I used for The Fretboard (LEAP#018) sitting on a shelf ever since. It’s almost been thrown out a number of times, but luckily I didn’t as it proved to be inspiration for this last-minute idea for a party decoration.

The basic idea, using as many on-hand parts as possible:

  • sound input
  • 2 LED strip circuits independently controlled and powered from 12V
  • simple Arduino sketch to sample the (more...)

LEAP#402 Rolling with the BoldportClub Pips

The BoldportClub Pips circuit is based on “Dicing with LEDs” by Elektor (December 2006), but with a new PCB designed as only Boldport can (and a flashy red baggie).

The ripple counter toggles through all die states at around 8.8kHz. Diode steering is used to light the appropriate LEDs for each state and reset the count when it gets to “7”. This runs fast enough that it appears all LEDs are on at the (more...)

LEAP#397 I²C Scanner

This is a simple sketch, inspired by i2c_scanner that simply scans for the presence of addresses in the full 7-bit address space.

This can be very helpful when trying to use I²C modules where the default address is not documented. As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub hero_image

LEAP#396 Capacitive Touch Organ

The MPR121 is a capacitive touch sensor. Originally produced by Freescale (now NXP), the part is end-of-life but still widely available, especially on breakout boards.

I wrote some code and built a little penny (5 cent actually) organ to test it out. It implements a simple 12-tone (chromatic scale from C5/523.25Hz) organ:

  • on interrupt from the MPR121..
  • uses the Adafruit_MPR121 library to get touch state via I2C/Wire
  • sounds the corresponding tone with a speak (more...)