Tea Gallows

thingiverse

https://www.youtube.com/watch?v=_GosO-r_sI8 Update: If you want to build the Tea Gallows with a professional PCB instead of a breadboard, look here: https://www.thingiverse.com/thing:2749364 The "Tea-Gallows" is a nice little gadget working with an Atmel Atmega328 on an application board. Pressing the button increases the brewing time indicated by LEDs for one minute until a maximum of eight minutes. A long press starts the countdown. The alarm begins ten seconds before the end with short beeps until finally, the tea bag will be pulled out through a weight falling down along a little pole made of stainless steel. The release process is caused by a tiny servo pulling back a bolt holding the weight in place. I decided to power it with 4.5 volts, supplied by three AAA-batteries. Therefore, there's no external crystal; besides, the microcontroller goes into power-down mode when the microcontroller is not active for ten seconds, consuming only about 25 microamperes. Programming the microcontrollers requires an ISP programmer because you have to set some fuses of the microcontroller, which you can't do with serial programming (I'm no expert, but I think that's right). I recommend using the following little application board: http://shop.anvilex.de/index.php?route=product/product&path=115_222&product_id=2641 You can use an Arduino NanoProMini too, but regarding battery life, you have to desolder a power LED and a voltage regulator. ISP programming requires a bit more effort because the Arduinos are mainly made for FTDI programming. Please make sure to use LEDs with integrated protective resistors; never connect a normal LED directly to a microcontroller. Don't forget the protective resistor for the photomos relay too; it will be damaged without.