Review on Eiechip DC to DC Step Up Boost Converter Pack of 10 - MT3608 with Micro USB, DC Voltage Regulator - Boost Module for 2V-24V to 5V-28V 2A Power Supply by Bernardino Suazo

I specifically use them to boost voltage from 3V to 5V (for USB devices) or 12V (for LED strips). I've installed two so far and they work pretty well. The pot is very sensitive, so you can turn it up tenths of a volt or less. The pads are pretty easy to solder. The power supply is relatively clean, I do experience some flickering on the LED strip but that seems to dissipate fairly quickly - for sensitive applications you may need to run a capacitor to clear things up a bit. The device is moderately efficient, but gets quite warm - when converting 2 AAA (3V) lithium batteries to 12V with an approximate consumption of 200mA, the converter (both the top of the transformer and the bottom of the board) heats up to about 116F for about three minutes of work. Pretty warm, warmer than you usually want. Instead I could try connecting 9V to see if that lowers the temperature a bit, or if that doesn't work add a thermistor to reduce the risk of a thermal event. However, I recommend for general experiments.