The 1PPS signal is connected to the Arduino Nano at an I/O line capable of generating an interrupt. The design also has a 32-bit counter that can be read and reset by the Nano. The 32-bit counter is ...

This is used to read the output pulses coming from the water flow sensor. When Arduino detects the pulse, it immediately triggers the pulseCounter() function. This function then counts ... of pulses ...

The duders over at cookinghacks put together an Arduino based geiger counter. It's set up to click a speaker at every pulse for an immediate indication of radioactivity.

[Martin] sent in a great guide to a simple Arduino based theremin. It’s a very small build – just a single common IC and some passive components – and easy enough to build in an a… ...

If so, Make Projects user Clement Storck built a simple Arduino powered notification system that sends him a text message and an email with a photo every time someone rings the doorbell.

Another simple circuit (if you don’t count the scope) that is useful for cable testing is a time domain reflectometer. Posted in Tool Hacks Tagged 555 , cable tester , decade counter , network cable ...