This little light is a keyring style flashlight styled on a handheld one. The lithium cells are sealed inside making it a disposable item, but the use of a momentary switch means it really is just a short use flashlight better suited to keeping as an emergency light in things like cupboards or stuck to distribution boards with the built in magnet. The heat sealed case suggests it's probably waterproof too. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- http://www.bigclive.com/coffee.htm ... https://www.youtube.com/watch?v=UooFK7nvwZs

How to use the classic STC-1000 clone thermostats, and a look at the circuitry inside them. I think the original version of these units may be Elitech. These modules are shockingly cheap for what is effectively an industrial control module. It's almost as if the software got out into the wild and everyone started cloning them in a common style of case. As with all generic grey-import products you should only consider them for personal projects and prototypes. For professional or critical applications it's probably better to go with a higher profile unit for better construction standards and higher operational stability. That especially applies to where higher current loads are being switched. Although these claim to be able to switch compressors and heaters I would only recommend doing so via an external rugged high current relay. I'd also suggest a 12V DC system as the 12V relay coils are more rugged. If you search on eBay for STC-1000 you'll find a lot of these at wildly different prices. Cost is not an indication of quality and what you get will be completely random - even when two are ordered from the same seller. Here's a super compact guide to programming them. The two main settings are temperature and differential (hysteresis), where the differential is the difference from the set temperature and is where the heating or cooling will kick in. The compressor delay setting is to avoid rapid cycling of the compressor to prevent it stalling by starting under pressure. The calibration function lets you tune the accuracy of the thermistor. Press the up arrow briefly to check the main temperature setting. Press the down arrow briefly to check the differential setting. To change a setting press the "S" button for a few seconds to enter setting mode, and use the arrows to step up and down through functions F1 to F4. To adjust the chosen setting press the "S" button briefly to display its current setting, and press and hold "S" while using the arrow keys to change the setting. If no button is pressed for a very ungenerous four seconds the unit will exit setting mode. On some units the settings may not be stored unless the power button is pressed briefly while in setting mode. F1 sets the required temperature. These units only operate in Celsius. F2 sets the differential in degrees where the relays activate either side of the main setting. F3 sets the compressor delay to between 0 and 10 minutes. F4 lets you nudge the calibration of the thermistor to match a more accurate thermometer. The temperature sensor is a very common 10K NTC thermistor. (10K ohms at 25C) If the sensor is open or short circuit the unit displays EE. Try to keep the sensor cable away from mains voltage wiring to avoid display instability. To turn the unit on and off ... https://www.youtube.com/watch?v=T4umSkJjXwY