What Is Inside Hand Heater From Aliexpress (With Schematic)

[@NickElectronics]

Link for the hand heater in case you want to buy it 🙂 shorturl.at/glpV8

[@prostosergik]

Could R17 be NTC?

[@NickElectronics]

Actually it can be. But it is strange that the marking "NTC" is on the other side.. and pads as well. Maybe it is duplicated just to be able to solder NTCs in two different packages. I will check it when I have time and will say if it is an NTC))

[@prostosergik]

@@NickElectronics It's pretty normal to replace expensive thru-hole components with cheaper SMD. Precise measurement of temperature is not that important there, I think it serves overheat protection purpose only. Try to heat it with lighter or soldering iron and check if it turns of heaters.