It is only general idea to create low power device with salt water cell as power supply. Here is example of salt water cell. It is made from:
- two glass containers,
- two copper electrodes,
- two silver electrodes.
Voltage generates by this two cell is around 1.5 volt. Here is example image:
I am thinking if it is possible to use this cell as power supply to electronic device like simple egg timer. Please comment below what you think about that.
It looks like that in current form salt water cell is able to generate voltage around 1.7 volt and current around 4-5 uA. As was mentioned in comments most important think is proper material and shape of electrodes. Here is video from quick test: