Category Archives: Sensor



Simple and Low Cost Dew Sensor

This is a simple and low cost dew sensor circuit that can be used to switch off any gadget automatically in case of excessive humidity. Dew (condensed moisture) adversely affects the normal performance of sensitive electronic devices. The main part of this circuit is a low cost dew sensor element (resistor type). Although dew sensor… Read More »

Light Alarm with Timer 555

Here is the simple and low cost light alarm circuit built using timer IC 555 as the sound generator and a LDR to sense the environment light. This alarm is activated when the light beam on the LDR photocell is interrupted (You can use the light of a flashlight bulb which will make you a… Read More »

Ultrasonic Distance Detector / Sonar Ranging System

This is the ultrasonic distance detector or sonar ranging system which can be used for general purpose. There are kit version available on the market, but of course the price is 3x more expensive than if you build your own sonar ranging system. Some application may use this circuit such as robot applications, body height… Read More »