Subscribe to Make Magazine Today!

LED Shift Register


The line of LEDs takes the inverted signals from a CD4017 counter, so that each LED generates light when the related outputs go to a low level. It works in bidirectional sequence. A 555 timer chip, in astable multivibrator mode, generates the clock signal. Circuit schematic & video Read more »

Earthquake Detector


An earthquake detector can be a useful home safety device because it alerts you to a quake some seconds before it happens. During an earthquake two kinds of waves are emitted from the centre: a small wave and a dangerous wave. The small wave is faster, so it is the... Read more »