LEAP#437 QX5252 Joule Thief

I recently “discovered” solar LED driver ICs, such as the QX5252 and YX805. They are mainly designed to drive LED lights from a low-voltage rechargeable battery, with colar powered charging.

A core function is a boost converter circuit (similar to a joule thief) that allows LEDs with a forward voltage of over 2V to be driven from a 0.9V-1.5V battery.

As a test and demonstration, I’m ignoring the solar charging aspect here, and (more...)

LEAP#436 Vivian the Vibrating BEAM Bot

Whatever happened to BEAM robotics? Perhaps it was just a 90’s fad, now rendered irrelevant by cheap microprocessors. But just as we still enjoy tinkering with 7400-series logic, old and irrelevant technology has a special attraction for some;-)

And it turns out that these days there are some new tricks - such as using the QX5252/YX805 solar LED driver to boost the output of the photovoltaic cell (it’s like a joule thief in a TO-94 (more...)

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...)

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


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...)