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Combo Microwave

Electronics Bay
Electronics Bay

Here are the internals of a cheap Microwave/Convection Oven combo. Electronics bay is pretty much the same as a standard microwave, with the magnetron, transformer & diode/capacitor voltage doubler, with the addition of an extra fan & a pair of nichrome elements to provide the convection oven function.

Convection Fan
Convection Fan

Convection blower which keeps the cooking vapours & smoke away from the elements, & circulates the hot air around the cooking chamber. This is a 12v DC centrifugal type blower.

Convection Element
Convection Element

The elements are inside this steel shield, air duct extends from the centre.

Thermal Cutouts
Thermal Cutouts

This oven has a pair of thermal switches on the magnetron.

Capacitor & Diode
Capacitor & Diode

The usual capacitor/diode voltage doubler in the magnetron power supply. The transformer is visible to the left.

Controller
Controller

Electronic controller PCB. This has a pair of relays that switch the elements & the magnetron transformer.

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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.