LEAP#442 Boldport ResPot

As any good electronics hobbyist must have done, I’ve already built a decade programmable resistor box - see LEAP#414 - but this is one with the Boldport twist. Yes, real pots.

A decade box is an old-fashioned bit of test equipment, allowing an arbitrary resistance to be dialed up to order.

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


LEAP#441 Pollen8

“Pollen8” is an exploration of contrasts and patterns in a freeform wire circuit.

I was interest in playing with a design that avoided the harsh angularity of most electronic circuits, instead using graceful lines that attempt to mimic a more organic structure.

The second goal was to achieve a chameleon-like LED display, where the visual effect depends on the perspective of the viewer: random from some angles, but clearly sequenced from others.

I created this (more...)

LEAP#440 Logging Data with Adafruit IO

I wanted a simple way to log the voltage of the LEAP#439 QX5252 Solar Night Light, rechargeable battery to get a sense of the overnight discharge and daily recharge pattern.

It didn’t need to be particularly accurate, but I did want to get a fairly continuous log at least every 5 minutes or so. Sounds like a perfect case for some Arduino-powered data logging!

I could just capture some data locally to an SD (more...)

LEAP#439 QX5252 Solar Night Light

Inside most solar-powered garden lights is an ingenious little circuit comprising a rechargeable battery, solar cell, inductor, LED and a little IC that does all the magic:

  • when voltage is detected from the solar cell, the LED is off and the battery will charge
  • as the solar cell voltage drops off (gets dark), the chip runs a switching converter (using the inductor) to boost the voltage from the 1.x V battery sufficient to drive (more...)

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...)