It’s a project called snapVCC, and it turns a 9 volt battery into a regulated 3.3 or 5 volt supply. The idea behind snapVCC is simple enough; just add a circuit board to the top of a nine volt ...

In this flashing led lights circuit, the LDR or photoresistor is connected in such way that when the light intensity varies it will influence the flashing. ... The whole flashing led circuit is ...

The whole circuit, complete with tiny speaker and an LED to indicate pulses, sits neatly on top of a 9-volt battery. The video below shows it in action with a test source.

This joule thief led or high efficiency LED with 1.5 volt driver is a tried and tested circuit built around some discrete electronics components. A common 5 mm high-efficiency white LED (D1) is the ...