Pulse Width Modulation or PWM technology is used in Inverters to give a steady output voltage of 230 or 110 V AC irrespective of the load. The Inverters based on the PWM technology are more superior to the conventional inverters. The use of MOSFETs in the output stage and the PWM technology makes these inverters ideal for all types of loads. In addition to the pulse width modulation, the PWM Inverters have additional circuits for protection and voltage control.

Here is an Ultrasensitive Heat Sensor to monitor high temperature in Electronic devices. It can be placed inside the electronic gadget that usually generates heat during its operation. The circuit also functions as a sensitive Fire Alarm. This heat sensor uses the piezoelectric property to sense heat.

Use this refrigerator alarm circuit to prevent leaving the fridge door open by sending out an alarm signal every time the door is left open for some time.
The sensor of the alarm is an LDR. After a short delay, it triggers an alarm signal and keep the signal on until the door is shut close.

It’s time for the Top 10 Electronic Circuits for June 2010.