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Dremel MultiPro

Front
Front

Here we have a Dremel MultiPro rotary tool, a main powered 125W 33,000RPM bit of kit.

Motor Assembly
Motor Assembly

Here the field & controller assembly is removed from the casing.

Armature
Armature

Here is the armature, which rotates at up to 33,000RPM. The brushes rise against the commutator on the left, next to the bearing, the cooling fan is on the right hand side on the power output shaft, the chuck attaches at the far right end of the shaft.

Speed Controller & Brush Box
Speed Controller & Brush Box

Here is the speed controller unit, inside is an SCR phase angle speed controller, to vary the speed of the motor from 10,000RPM to the full rated speed of 33,000RPM.

Mains Filter
Mains Filter

This is the mains filter on the input to the unit, stops stray RF from the motor being radiated down the mains cable.

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Hair Dryer

Housing
Housing

This is a 1500W hairdryer, death caused by thermal switch failure.

Switch
Switch

This is the switch unit. Attached are two suppression capacitors & a blocking diode. Cold switch is on right.

Heating Element
Heating Element

Heating element unit removed from housing. Coils of Nichrome wire heat the air passing through the dryer. Fan unit is on right.

Thermal Switch
Thermal Switch

Other side of the heating element unit, here can be seen the thermal switch behind the element winding. (Black square object).

Fan Motor
Fan Motor

The fan motor in this dryer is a low voltage DC unit, powered through a resistor formed by part of the heating element to drop the voltage to around 12-24v. Mounted on the back of the motor here is a rectifier assembly. Guide vanes are visible around the motor, to straighten the airflow from the fan blades.

Fan
Fan

5-blade fan forces air through the element at high speed. Designed to rotate at around 13,000RPM.