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
An op-amp is used as an oscillator in this LED flasher circuit. This is another circuit that can easily be built on an electronic breadboard by beginners in electronics. Click the above link for the circuit diagram.
This circuit uses a 555 timer IC and produces a fixed frequency audible tone that is played through a loudspeaker. No amplifier is necessary as the 555 puts out a signal of high enough amplitude. The circuit is easy to build for beginners in electronics and can be built on an electronic breadboard. Click the above link to find the circuit diagram.
This two transistor metronome circuit can easily be built on an electronic breadboard. The circuit is easy enough for beginners in electronics consisting of only six components, a loudspeaker and a nine volt battery or 9V power supply.
Find the circuit diagram for the metronome at the above link.