This sonic screwdriver has one purpose - to remotely control plug sockets using a 433MHz radio... and it fulfills that purpose rather well!
After lots of 3D printing (including quite a few failed prints) and even more glueing, the finished sonic screwdriver came together and I recorded the design, build and test process in a video. Check it out if you're interested.
The key part to this project was getting a circuit that was compact and optimised for long battery life. To achieve this, I designed my own PCB that used an ATtiny85 as the microcontroller.
I used an AA battery to power it, but as these only output 1.5V, I added a step-up voltage regulator to get the 5V required to power the rest of the circuitry.
Another cool touch is that the circuit is only formed when the button is pressed. Therefore, when the button is in its normal state (not pressed), there is no circuit so no power is drawn from the battery.
The battery is only drained when the button is pressed, which is only for one or two seconds a day!
If you want to dive deeper into the circuitry, feel free to have a look at the cartoonified diagram.
The 3D printing was also quite challenging and I struggled to build the CAD model due to the free-form surfaces and organic shape.
Luckily, after lots of different approaches, I landed on a successful design and started the 4-hour printing process. After a few failed prints due to poor support design, I finally managed to get a good print of the sonic screwdriver body, as you can see in this picture.
With the prints ready and the circuitry assembled, the last thing to do was to apply lots of glue and close up the casing.
If you're wondering where you can find out more about the design, code and circuitry, this project is fully open source and you can get all the details and files you'll need here: http://hartleyhacks.com/making/sonic-screwdriver-plug-socket-controller/
I hope you enjoyed reading through this - if you have any questions, please feel free to leave a comment, I always enjoy getting feedback and thoughts from fellow makers.