Here’s a hairdryer that got to the end of it’s useful life. As you can see they are really pretty simple. Basically all you’ve got is a heating element (behind the front grille) and a fan to blow air around it. Of course there’s always an on/off power switch.
This one has a couple of extras that are pretty common:
1. A safety cutout in case the fan packs up and the dryer gets too hot. (It’s the silver thing on top of the black heating element housing.)
2. Half power setting – you can’t see it in this photo but there are actually two switches side by side. The first switch turns the dryer on but power is routed through a diode at the back of the switch. This makes the dryer run at half power. When the second switch is turned on the diode is bypassed, allowing the hairdryer to run at full power.
This type of hairdryer uses a tangential fan – that’s a type of fan that blows air sideways. Many hairdryers use conventional fans that look like propellor blades. These blow air along the axis of rotation, like a plane propellor.