Abstract: A heating oven has a weighing apparatus, and a weight of a food material placed on a tray in a heating cavity is conveyed by Roberval mechanism. The conveyed weight is measured by the weighing apparatus, and the heating oven controls heating time, heating power and the like responding to the measured weight of the food stuff.

Abstract: A power feed apparatus in which a means for by-passing the current reversely biasing the load is used for the normally used rectification means when the power converted by the transformer is fed to the reversely blocking characteristics like magnetron, whereby the price is lower and the shape is more compact without the use of the rectifier, because of the combination construction of the reverse bias current by-pass means and the inductance element provided in the load current path with respect to the non-linear load like the magnetron.

Abstract: A heating apparatus comprises a housing having a chamber and a door for closing the chamber, and a power supply source to supply heating energy to the chamber. A door-close sensor is provided for detecting when the door is closed. A foodstuff is placed on a table which is vertically movably mounted in the chamber on a resilient support so that the table may oscillate at a frequency determined by the weight of the foodstuff. The housing may be constructed to transmit an impact to the table at the instant the door is closed, or alternatively, means are provided for causing the table to oscillate at the frequency in response to the door being closed. The oscillation of the table is converted to an electrical signal and analyzed to determine the weight of the foodstuff. The power supply source is controlled in accordance with the determined weight.