Magic Smoke

Shiny LED Panels Run Hot

2021-06-09T17:26:00.184-04:00

LED panels are great for grow lamps and all sorts of other purposes, but they are liable to overheat if the back surface is bare aluminium. Simply painting the top of the panel could almost double its thermal capacity, allowing you to run it at much higher current.

Source: Brompton Technology

Adafruit Lost A Customer

2020-05-30T10:54:00.007-04:00

Last week I placed a $200 order with Adafruit. Today, after finding out that the order had not been processed in any way, I asked Adafruit when it would ship. The customer support representative could not say. Then, without any prompting from me, she cancelled my order and told me to find a new supplier. Apparently, my query was so unwelcome that Adafruit doesn't want my money, or indeed any future orders. :/

Update, June 11th. The Adafruit website now states that "Non-urgent orders are shipping within 7-10 business days, sometimes sooner." Why couldn't Kelly have told me that when I asked? In addition to cancelling my order, I now find out that Adafruit has also placed my shipping address on a blacklist to prevent future orders. If you are reading this, Limor Fried — thanks for nothing.

Pi Zero Print Server

2020-05-24T00:42:00.012-04:00

I can't believe it! I actually finished a project the same day that I started it. A while back I won a Raspberry Pi Zero W in a promotional competition for Zipcar, and today I set it up as a wireless print server.

Valentine's Day Wearable

2020-02-14T20:03:00.000-05:00

Recommended attire for Valentine's Day. Please note the electronic accessory, held in place with a barrette ;)

Magic Mote MSP430G2553 Wireless Sensor Node With NRF24L01+ Module

2017-03-17T20:49:00.000-04:00

Proto Cape For BeagleBone

2014-02-21T12:06:00.002-05:00

This add-on board for the BeagleBone or BeagleBone Black allows easy prototyping using through-hole components. More than 300 sold on Tindie!

Hacked Wall Clock (after Lord Vetinari)

2014-02-09T10:54:00.000-05:00

This clock ticks erratically but still keeps accurate time. Its mechanism has been replaced by a programmable chip that emits 64 randomly spaced ticks every 64 seconds.

February Swag Bag: Noritake VFD

2014-02-07T23:56:00.000-05:00

Noritake recently offered samples of these impressively bright 16 x 122 pixel graphical vacuum fluorescent displays. Their GU7000 Arduino library is easy to set up and use: it took just a couple of minutes to get out this message. I like!

Daisy Chainable I2C Level Shifter

2014-02-07T12:50:00.002-05:00

An improved I2C level shifter PCB compatible with the daisy chainable I2C splitter.

Lo Fi Blinky Card

2014-02-03T13:52:00.003-05:00

Snow day project with 4 year old Rachel: a greetings card with flashing illuminated LEDs.

Daisy Chainable I2C Splitter PCB

2014-02-02T00:04:00.001-05:00

One of a series of modular expansion boards for the I2C bus: a 1-3 splitter for branching I2C signals.

Valentine LED Chaser

2014-01-25T20:45:00.001-05:00

The object of your desire will not be able to resist this heart shaped kitsch-o-tron, lovingly hand-crafted on perfboard with a CD4017B decade counter and 555 astable. But you probably can't go wrong with flowers and chocolates as well. Just to be on the safe side. Kits now available from Tindie!

$1 Lithium Coin Cell Charger

2014-01-16T21:22:00.001-05:00

Got a buck? Make a charger for LiR2032 coin cells. It could hardly be cheaper or easier.

Magic Mote Thermostat and Wireless Temperature Sensor

2013-12-31T21:52:00.000-05:00

A homemade thermostat up in the basement rafters controls the heating in my home. The smart bit is the radio frequency communication that connects it to a remote temperature sensor.

Magic Mote Wireless Sensor Node

2013-12-31T21:51:00.000-05:00

This compact PCB interfaces a low power MSP430G2553 microcontroller with a Nordic NRF24L01+ 2.4 GHz radio frequency transceiver module. It's well adapted to serve as a wireless sensor node, but has enough I/O options to be put to use wherever a small microcontroller is required. PCBs now available from Tindie!

Home Grown Bhut Jolokia Peppers

2013-12-24T02:21:00.004-05:00

Hannah and I made chili sauce from the devilishly hot Bhut Jolokia peppers that I grew this year.

12mm Rotary Encoder Breakout

2013-12-23T00:40:00.001-05:00

0.925" x 0.925" breakout board for 12mm rotary encoder with switch. The PCB has enlarged holes to fit generic encoders.

Booting Linux Live USB on a MacBook Air

2013-12-22T15:11:00.002-05:00

I have a MacBook Air with an Intel i7 core running OS X Lion 10.7.5. Booting linux from a flash drive was not straightforward, to the point that when I finally got it working I laughed with surprise. Evidently doing such things is not part of the one true Apple way. The instructions were cobbled together from from here and here with a fair bit of trial and error. Needless to say, the procedures documented on the Ubuntu website did not work for me.

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Stirplate Hot Fix

2013-12-09T22:59:00.003-05:00

A digital stirring hotplate in decent used condition will set you back about $250. I paid a fraction of that for one with a broken heating function. The problem turned out to be nothing more than a duff switch.

I Wanted A Puppy For Xmas

2013-12-06T23:17:00.001-05:00

... and Digikey made my wish come true. I'm planning a home automation system, and this little computer will be its brain.

Homemade MSP430 Launchpads

2013-12-04T23:27:00.001-05:00

When I ordered some NRF24L01+ boosterpacks from the 43oh store, I asked for a couple of MSP430 Launchpad v1.4 PCBs. These are legacy boards kindly provided by TI (thanks LariSan!) It was fiddly soldering to the tiny 0402 pads since my components were all 0805. The LEDs were especially tricky. But they both turned out OK as you can see. Here they are (alongside a genuine Launchpad on the left) running the breathing LED demo from the OSX Launchpad toolchain.

A Little Something To Be Thankful For

2013-11-30T09:05:00.001-05:00

Thanks Elecrow for a $10 voucher in their Black Friday giveaway. I have heard good reports about their PCB prototyping service, especially the free color option, and I am keen to give it a try.

Pedal Powered Menorah

2013-11-27T21:00:00.000-05:00

Exercise bike + magnets + LEDs = festival of light. Devised by T.J.Hunt with specialist engineering expertise from Rabbi Shena Potter Jaffee. Come along 3rd December to the Mayerson Jewish Center of Cincinnati. Pop a beer, grab a latke, and take a spin. Happy Hannukah!

Twin Triac AC Switch on DP5050 PCB

2013-11-24T04:30:00.000-05:00

Two triacs switched by zero-crossing optocoupled drivers act as solid state relays on a Dangerous Prototypes standard size PCB.

Twin Relay Control Board on DP5050 PCB

2013-11-23T16:56:00.000-05:00

Just for good measure, a breakout board for twin Songle SRD series relays to fit the Dangerous Prototypes standard PCB size DP5050.