While it’s the easiest way to lay out a simple circuit for prototyping, breadboards are a pain. They are the ultimate kludge; they work well enough, but no one will ever say that a solderless ...

Use every drop of energy from a 9-volt battery by adding it to an LED Blocklite. I was always stumped about what to do with partially depleted, 9-volt smoke detector batteries. They’re usually drained ...

A 555 timer can be used to generate a squarewave to produce a negative voltage relative to the negative battery terminal. When the timer output at pin 3 goes positive, the series 22 uF capacitor ...