Inside a Xiaomi Mijia mosquito repeller. (Including cartridge reset info.)

This teardown was interesting, not just because of the circuitry and clever cartridge monitoring technique, but also because it made me look for information on Transfluthrin and how it works.
Transfluthrin is a synthetic insect repellent/killer based on a naturally occurring chemical from Chrysanthemum plants. It has a history dating back to the 1800's.
The chemical works by affecting sodium channels in nerves resulting in rapid effect against insects which are largely controlled by nerve reactions.
It has a low toxicity to humans because it is rapidly metabolised and no significant accumulation. But it can cause health problems if ingested or with high exposure that may have temporary effects on the nerve system.
At this point in time Pyrethrins (of which Transfluthrin is one) are regarded as the safest pesticides with low environmental risk. The common plug-in oil vaporisers usually have the transfluthrin in a carrier oil (kerosene?).

I subsequently did a current test on the cartridge's LR44 cell by slipping a piece of thin card with copper foil on either side between the cell and the contact. That let me put a meter in series to measure the current. In standby no current is drawn from the cell. When running a current of 180uA (0.18mA) is drawn.

I've got another Xiaomi unit on order that is smaller and operates in a different way.

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