This little torch is designed to plug into your phone's charging port and be powered from the phone.
The main advantage of this is that it provides a more directional beam than your phone's camera flash, and will also operate with the phone off.
I wasn't expecting much circuitry in this. Just a little control chip, transistor and resistor to limit current through the LED. But I was wrong. It has a complex two transistor toggle switch and a current regulated LED driver.
The complex circuit and tiny PCB made this a very difficult device to reverse engineer.
It came from AliExpress and will usually appear in the bundle deal section:-
https://www.aliexpress.com/item/1005008959702525.html
It should typically cost less than £2.
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https://www.youtube.com/watch?v=cC-1N3eF9yE