Light, RPM, Heating to name just a few of them.
Dimmer circuits are a good introduction to Power Electronics.
Here you will find Schematic Circuit Diagram for DIY and further information on Dimmer Circuits
|Simple Dimmer with Diac/Triac||www.geocities.com/tjacodesign/dimmer/dimmer.html|
|Microprocessor controlled Three Channel Dimmer for LED's (RGB-Dimmer)||www.loetstelle.net/projekte/rgbdimmer/rgbdimmer.php|
|12V DC Dimmer,PWM Based||home.berg.net/opering/projekte/8/index.htm|