This USB LED torch is an easy project for beginners in electronics and requires some soldering. The torch can be used as a conventional torch or an emergency light during mains power failure.
It can be powered from any USB host port. The image below shows a USB power pack that is sold as a solution for charging USB devices on the go. If you already have a USB power pack, the USB torch can be built for very little cost and carried with you wherever you take your power pack.
USB Battery Power Pack and LED Torch
The torch is shown below powered on.
USB LED Torch Powered by USB Battery Pack / Charger
The temperatures are displayed on two gauges on the web page hosted by the Arduino web server. The two sensors can be used to measure an inside temperature (e.g. inside a building or room) and an outside temperature (e.g. outside air temperature).
To keep the design simple and easy to lay out on a single sided board, only 5 GPIO pins were connected to a socket strip – this is fine for initial experimentation. The serial port allows the Raspberry PI to be connected to a PC without the need to connect a keyboard and screen to the Raspberry PI.
This Arduino voltmeter measures four independent voltages and displays the results on a liquid crystal display (LCD). Each channel can measure up to about 50V DC which is achieved by adding a voltage divider to each channel. Click the above link for more details, a circuit diagram and Arduino sketch code.
The large brick-type open source PLC has 22 digital inputs, 6 analog inputs and 16 transistor outputs. It also features a SD card socket, 2 RS-232 ports, 1 RS-485 port, 1 USB device port and a JTAG port for programming and debugging.
Large Open Source PLC
All the source files including circuit diagrams for building the large open source PLC are available for download at the above link.