TritiLED Flashes for 20 Years on a Single Coin Cell

From  on Tindie blog:


TritiLED Flashes for 20 Years on a Single Coin Cell

Ted Yapo had a small problem. As an amateur atronomer and astrophotographer, he needed a way to mark his expensive equipment so that he wouldn’t trip over it in the dark. Glow-in-the-dark materials were out because of they only glow for a short time, and glow sticks were also less than ideal because of their single-use nature. Tritium light sources would be perfect, barring the small details that they’re radioactive, expensive, and in the US only a few uses are allowed, most are prohibited by law.


So Yapo instead came up with an LED light that can run for not 20 hours, or even 20 days, but 20 yearson a single CR2032 coin cell battery!

TritiLED Flashes for 20 Years on a Single Coin Cell

reDot Smart 5×7 LED Matrix

Alex on is working on a smart miniature (DIP6) 5×7 LED Matrix:



This project is based on my #reDOT project. Basicly it is a 5×7 SMD LED Matrix an a microcontroller on one PCB. I started wirh 0201 LEDs (see first project log), but this was not reliable. So a second version with 0402 is in development. 0402 LEDs do have some benefits over 0201:

  • bigger and you can solder them better
  • cheaper
  • more colors availible

The microcontroller (a low coast STM8) drives all LEDs directly with multiplexing. For controlling a UART interface is available. The dimensions are like a DIP-6 package. For easy connection of multiple PCBs, the pads are castellated. Also the supply rails are available on both sides. So multiple of these display can be soldered together to a bigger display without the need of additional wiring.

reDot Smart 5×7 LED Matrix

LED ring

Jens Hauke designed this charlieplexed 20 LED blinker controlled by an ATTiny45 for the Hackaday Coin Cell Challenge:


LED Ring

This is a small blinky with 20 LEDs powered by one CR2032 coin cell
and with an ATTiny45 brain. The firmware is written in plain C and
compiled with the avr-gcc toolchain. The PCB is a two layer design made
with KiCad.
Space efficient daisychained LED placing with shared anode/cathode soldering pads.

Firmware and gerbers are available on GitHub:



Jens has shared the board on OSH Park:

LED 20 Ring ATTiny


Order from OSH Park

Here is a video of the LED in action:

LED ring


A holiday project by Dan Hienzsch (@rheingoldheavy) to build a little Snowbot with an adjustable speed larson scanner for an eye:


Snowbot V1.0

The Snowbot has three major subsystems: Power and Timer and Display.

Power Subsystem

The power subsystem uses a 3.7V LiPO battery boosted to 5V with an SC4503 boost converter to power the fully analog circuit. It requires a set of passive components in order to generate the higher voltage.


Timer Subsystem

The timer subsystem is comprised of a 555 IC that generates a clock signal. The speed of the clock is adjusted by twisting the potentiometer (the nose of the snowbot). The clock signal ticks through the outputs of a CD4017 decade counter, lighting each LED in sequence, then moving back through them again.


Display Subsystem

The display subsystem involves taking the output of the CD4017, and directing it to six red LEDs in the form of a larson scanner. In addition to lighting the LED, the current also charges a 22uF capacitor through a diode. When the output moves to the next LED, the cap discharges through a 2.2K resistor (part of a resistor network), fading the LED out gracefully.


How Fast is Your Fidget Spinner?

From Ken Olsen of The Maker’s Box:

How Fast is Your Fidget Spinner?

You never know what people will do with your ideas, and it is always fun to see someone do something I would have never thought off with them.  I got a video from someone who built my Programmable Fidget Spinner, and used a leaf blower to see how fast they could get it to go.  Fortunately, they were wearing safety glasses, and no, it didn’t come flying apart.  It did, however, start displaying erratically at about 3600 RPM (the fastest I can get it by hand is just under 2000 RPM).

So, what is going on?  TLDR: I figured it out and fixed it, and here is proof.

How Fast is Your Fidget Spinner?

Maker Faire Orlando soldering kit


We are proud to be a sponsor of this Maker Faire Orlando soldering kit:

Advanced soldering training at Maker Faire Orlando

For the past six years at Maker Faire Orlando, members of FamiLab have taught attendees how to solder with a cool little Makey pin with 2 self-flashing LEDs.  We’ve been asked for more advanced soldering training, and we responded with the addition of a PIC-microcontroller-based board twinkling several LEDs, and with a switch that can be used to change the LED display pattern.

We opted to design the board such that it can be used as a pendant on a necklace (lanyard) or as a keychain (especially for those of you who like large keychains). The design is a scalloped 2.7″ circle with LEDs on the outside circle, and a hole at the top for a keyring. Batteries are on the back of the board.


Maker Faire Orlando soldering kit