Here is a motor speed sensor module, the major goal is to check the rate of an electric motor. The module can be used in association with a microcontroller for motor speed detection, pulse count, ...

Although this circuit connects the DS18S20 1-Wire temperature sensor to a Cypress CY8C26443 PSoC microcontroller, designers can easily adapt it to connect other 1-Wire devices to any microprocessor.

A way to apply the output of certain sensors to a TTL/CMOS-level iput on a microcontroller. Sensor must have an NPN output stage that can support a pullup to its power rail.