Step 1: Circuit Design
Here are components that I chose:
ATMega328p with 16Mhz crystal – I chose this micro-controller because it is extremely easy to use. There is also a good community support, as ATMega328p is used in one of Arduinos.
Ina12P amplifier – this device is created specifically for amplification of sensors' signals. It is not hard to use it. The only thing that I found tricky is figuring out the right resistance value for amplification gain.
TPS2020 switch – this is a great switch with a very low standby current ( <10 μA). I use it to control power of the servo that chimes.
MAX1555 charger – this device controls charging of device's lithium-ion battery.
2N3904 transistors – used to control lamps' power.
Lamps – I chose incandescent lamps out of esthetic reasons. Since I wanted to give the project a "vintage" look LED lamps did not quite fit the design. Although these lamps consume more power the feeling they evoke is quite worth it.
This device is able to work 3 weeks on a single charge.
Full schematic could be found on Github.
Step 2: Printing the Circuit
Step 3: Programming
Step 4: Enclosure Design
Step 5: Putting Everything Together
I would be happy to answer any questions and hear any comments about this project.
I also hope this device will inspire you to create some creasy contraptions of your own!