LEAP#434 Boldport Krell

The Krell is a handheld DSP synthesiser, with Buttons and potentiometers dial up a range of sounds. The Boldport project is a typically beautiful remix of a soldering project by James Hutchby of MadLab.

At the core of the circuit is a Microchip dsPIC33EP128MC202-I/SP. It’s an interesting choice - a digital signal controller that is really designed for precision motor control, now put in service of creating music (or at least weird sounds).

This project (more...)

LEAP#433 0-30V/3A Adjustable Power Supply Kit

The 0-30V/3A Adjustable Power Supply Kit at the heart of this build will no doubt be instantly recognisable to anyone familiar with the usual online electronics market places. It features continuously variable output voltage, and a variable current limit with overcurrent indicator/shutdown.

It appears the curciot design may have originated from SmartKit in Greece, been improved by various people, and at some point the “canonical design” was picked up for mass production (instantly identifiable (more...)

LEAP#430 Driving Scavenged Linear Steppers

CD/DVD drives are a great source of interesting scavenged components - in particular laser units and stepper motors.

I pulled some of the head control stepper motors some time back. They are small 4-wire bipolar stepper motors with a worm drive for linear motion. Datasheets are non-existent(!), so this is a little project to figure out their specs and demonstrate driving the units with an Arduino and bespoke H Bridge control circuit.

As always, (more...)

LEAP#429 3×7 Pomodoro Timer

Over the years, I’ve become habituated to working in a Pomodoro style - make the day a series of tasks worked on in short blocks of time, with take regular breaks. But I’ve never actually used a timer - just relied on my internal clock to work in roughly 1 hour increments.

As I was building the Boldport 3x7, it started to appeal to me as a very nice display to use for a non-distracting (more...)

LEAP#425 Look Inside a 7-segment with the Boldport 3×7

A lovely PCB and classic Boldport instructions(!):

This project is a challenge to construct.

The Boldport 3x7 is essentially a 3-digit common-cathode 7-segment display, rendered with discrete components.

Since it’s a chance to look inside the workings of a 7-segment display unit, I decided to modify my build to flip the lid and expose the internal wiring for inspection. Now it’s built, more projects to follow!

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

rclone Systemd startup mount script

rclone Rclone is a command line utility used for reading and writing to almost any type of cloud or remote storage. From Google Drive to Ceph, rclone supports almost any cloud-based remote storage platform you can think of. You can perform upload, download or synchronisation operations between local storage and remote cloud storage, or between remote storage

LEAP#423 The Maker UNO

I was recently shown an Arduino-compatible board made by Cytron in Penang, Malaysia called the Maker UNO. I gather it began life as a very successful kickstarter that aimed to produce a better board and associated teaching materials for K-12 education.

It packs some nice additional features in the Uno form-factor:

  • LEDs on all digital pins
  • a piezo buzzer on pin 8
  • a push-button on pin 2

Aside from looking pretty spiffy, a really nice (more...)

LEAP#422 VL53L0X Laser Tape Measure

The VL53L0X is a very small Time-of-Flight (ToF) ranging sensor. It is quite widely available as a module, including from Adafruit - see their information page.

For this project I’m taking the module for a test drive and building a short-range tape measure with an Arduino and Nokia 5110 display.

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


gitignore file for Go Projects

This is a gitignore file for a Go project to ensure temporary files and build files are not added to git repository commits. [crayon-5bbdc2270ee85958079321/]

LEAP#421 LimeSDR First Look

I think I first heard about LimeSDR-USB on The Amp Hour.

I was convinced to jump in and give it a go particularly because of the fully open-source nature of the platform - from hardware all the way to software, including FPGA code.

The unit is suited to research and development in a wide range of areas, but I suspect as I get more into this I will be mainly focused on areas such as (more...)

LEAP#420 CuttleTalk Audio over LiFi

Now I’ve built the Boldport lite2sound, time to test it out. I’m inspired by LEAP#417 SimpleSamplePlayer to attempt some LiFi audio transmission by light.

I’m using the Boldport Cuttle (an AVR/Arduino clone) to transmit an audio sample with an LED, and the Boldport lite2sound as a receiver. The audio out from lite2sound is amplified with LEAP#210 TDA7297 Kit.

As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on (more...)

LEAP#419 Boldport Lite2Sound

The Boldport Lite2Sound BC is a crafty collaboration with Rare Waves LLC. It uses a photodiode to detect audio-frequencies from light, which are amplified and piped to an audio jack (or optionally to direct line-out).

Best of all - it comes in an Altoids-sized can!

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


List of Bank Holidays For England in SQL Format

First off, create a table to store the bank holiday values. You may need to adjust this slightly depending on your SQL server technology being used (this was tested on MySQL Server).  [crayon-5bb4e0b3b1755979540269/] Insert the bank holiday values below. This table is currently for 2012 up to 2019 for England and Wales.  [crayon-5bb4e0b3b175d512369946/] For a

MySQL/ MariaDB Error Code: 1329. No data – zero rows fetched, selected, or processed

The above error can occur when calling a cursor results in no rows, or no more rows if called in a loop. Whilst the error message is descriptive about what has happened physically, you may wish to catch the error so that you can do something else, or simply replace the generic database error with

How to exit from a MySQL/ MariaDB Stored Procedure/ Function Prematurely

MySQL and MariaDB enable you to define your own error conditions and to report back to the SQL client both a return code and an error message. As soon as you raise the condition then MySQL/ MariaDB will halt any further execution of the code and report the error back to the client. This can

CockroachDB systemd script

This is a simple systemd script for CockroachDB. It works for single node installations or multiple nodes, however you’ll need to manually join each node to the cluster before using the systemd script. Create the systemd file and add the following content: [crayon-5bb2054895a8d904003843/] [crayon-5bb2054895a94089396086/] If your host belongs to a cluster create a hosts file

gitignore file for Eclipse Projects

This is an example of a .gitignore file for an Eclipse project to ensure temporary files, build files and project settings are not added to repository commits. [crayon-5bae3d499e098261603457/]

How to change the listening port for PostgreSQL Database

The default TCP port for PostgreSQL is usually 5432, however this can easily be changed in the postgresql.conf configuration file, which is the main configuration file for the database server. In addition to a TCP listening port, PostgreSQL will also a local socket if the server is running in a Linux/ Unix environment. A local socket is

gitignore file for Nodejs Projects

An example gitignore file for Nodejs projects to ensure that local environment variables, build related output and modules are not committed to the git repository. [crayon-5bad139c32c17821581453/]

gitignore file for Netbeans Projects

A gitignore file for most Netbeans projects to keep the build and local configuration files out of your git repository. [crayon-5bad139c338b6810432445/]