#electronics
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Strobeshnik HDD Clock (sensi.org)"There's an IR LED and a phototransistor pair mounted under the outer rim of the platter. A thin piece of black foam absorbs IR light and it generates a fairly sharp negative pulse on the output of the phototransistor."
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Building a Desk Bell for Kickstarter Alerts with a Raspberry Pi Zero
Here is a writeup of how I built a desk bell for Kickstarter pledge alerts using a Raspberry Pi Zero and a solenoid.continue reading... -
Every time I think I can do an electronics project I end up š”. Tried to hook up a @digistump Oak and can't even get it to connect to wifi! -
The old Fitbit and Fuelband which Aaron Parecki gave me a few years ago (thanks Aaron!) donāt hold a charge anymore. The Fitbit battery is near impossible to replace, and with the Fuelband I decided that as thereās no way of loading custom firmware (which would let me get at data without an internet connection and proprietary apps), it wasnāt worth trying to get replacement batteries. So before throwing the devices away, I took them apart.
I didnāt find out much which I hadnāt already seen in teardowns, but these devices have such strange form factors that it was fascinating to see the engineering up close.
The rubber coating comes off very cleanly. Here you can see some of the funny curved traces used on flexible circuit boards:
The LED array, with āJust Do Itā written on the top of the PCB (invisible to the end user). On the sections of flex between the more solid boards you can see the unbelievably fine traces:
On the back of the LED matrix section, with a part number. To the right you can see the jaggedy bluetooth antenna trace:
The fitbit isnāt so interesting. Removing the cap with a heatgun reveals a tiny circuit board with a tiny battery and vibrating element.
I also opened up the dock, as I noticed that the USB cable was power only, with no possibility of wired data transfer. The third pogo pin must be for the reset switch, which is mounted in the dock. Thereās a little IC in there too, but I was more interested in seeing how the pogo pins were attached to the board. Turns out theyāre just soldered straight on:
Iād love to have been able to flash custom firmware to the Fuelband, itās a lovely bit of hardware, and manufacturing something like that is completely out of the question for a hobbyist. There are so many fun things which could be done with a device equipped with an LED matrix, accelerometers and bluetooth ā a wearable MIDI controller, for example.
That possibility would also have made replacing the batteries worth doing, and in doing so saved the device from the landfill. Free software and open hardware isnāt just political, itās better for the environment.
