Lost component 04H-10 5873J01

04H-10 5873J01? No such references on the internet!
The little tabs are still a mystery to me.

I had a bunch of these SMT components which I did not index properly 4-5 years ago (promised, that was the last time I ever was lazy). Sadly, their reference 04H-10 5873J01 brought nothing back on the whole internet... They came in proper SMT strip and they are large enough to sport decent markings though. Alas, I called for help on G+ and/but I ended up sacrificing one open. Initially I thought they were atmospheric pressure sensors, because of the opening to the side.

But no, they are just completely dumb SMD electromagnetic buzzers. The kind with an old-school little coil that pulls a small metallic disk. Nowadays we tend to see more of the piezo electronic kind, but they still have a role because they slightly smaller and they work at a lower voltage (they are just bad in every other respect!). Being passive, they also need variable current to emit sound (they simply click once with a constant current), and I suspect they are able to vibrate at more than one frequency, i.e. they might be able to transmit sound and voice when a piezo buzzer cannot. I would have to check these ones, but I do not expect their frequency response to be good anyhow.

Charge a smartphone battery without the phone nor the charger

I shortly dipped my phone in sea water and the charging/battery control circuitry and micro USB plug got oxidized beyond repair (salt is really terrible). I could have saved it at the time if I had a chance to open it and carefully rinse the electronics with non-salted water immediately, but I miss my tools on holidays... While waiting for a replacement part to arrive, I had to recharge the battery the DIY way.

Recharge a smartphone battery with a super cheap lithium ion recharging module and pogo pins.
The short pieces of thick copper wires (in blue) are compulsory to present the retractable pins correctly
They are maintained in perfect contact with clamps on a soft silicon mat.