In addition to the WeMos battery powered temperature server, it would be nice to know what the remaining level of the battery is, so we can recharge it in time. This is easily done using a voltage divider circuit and the analog input on the WeMos D1 mini module.
Blink LED is a Hello World! application for microcontrollers. If you manage to get it running, you can assume that you are all setup and ready for further developments on your board. In this blog item I will cover how to do that on a STM32F407 Discovery board.
A while back I have assembled this bench power supply kit, which I received as a gift from my friend Eric. The kit was published in a Dutch electronics forum (Circuits online) as PCB Lab voeding. It was time to create a casing for it as it was just lying around in my drawer and was not really being used.
18650 batteries are known for it's high energy density, but this comes at a price. In order to protect the battery from overcharging or overdischarging a number of ICs need to be used. Luckily these charge and protector circuit boards are readily available for sale in all shapes and sizes. In this blog post I am going to build a charger that uses such a circuit.