High efficiency autoregulating heater

A heating device comprising:

• a current conductor having a plurality of serially connected substantially parallel turns sequentially spaced along a longitudinal axis,
• said current conductor having means for connecting it across a source of high frequency constant current,
• a sheet of high permeability magnetic material closely adjacent to an extended area of said turns,
• means for insulating said series of parallel turns from said sheet, and
• a source of high frequency alternating current for feeding a constant current through said conductor, to induce current in a confined region of said sheet thereby heating said sheet,
• said series of parallel turns and said sheet being arranged in such close proximity and the permeability of said sheet and the frequency of said alternating current being such that, the path of current induced in the sheet is substantially lengthened, and the impedance of the current path substantially increased,
• said sheet being heated to a sufficiently high temperature that its permeability substantially declines.

A soldering iron, comprising:

• a current conductor having a plurality of serially connected substantially parallel turns sequentially spaced along a longitudinal axis,
• a source of alternating current for feeding current through said conductor,
• a sheet of high permeability magnetic material closely adjacent to an extended area of said turns,
• means for insulating said conductor from said sheet,
• said sheet being heated at least in part by induction to a temperature sufficiently high to cause the sheet's permeability to decline substantially,
• a sheet of high electric and thermal conductivity in electrical and thermal contact with said magnetic sheet, and
• a heat transferral tip heated by one of said sheets.

A soldering iron, comprising:

• a current conductor having a plurality of serially connected substantially parallel turns sequentially spaced along a longitudinal axis,
• wherein said conductor is configured for connection across a source of high-frequecy alternating current,
• a sheet of high permeability magnetic material closely adjacent to an extended area of said turns,
• means of insulating said conductor from said sheet so that said sheet is heated by induction to a temperature sufficiently high to cause the sheet's permeability to decline substantially, and
• a heat transferral tip heated by one of said sheets.

An article of manufacture constituting a heat generating cartridge comprising:

• a current conductor having a plurality of serially connected substantially parallel turns sequentially spaced along a longitudinal axis,
• wherein said conductor is configured for connection across a source of high-frequency alternating current,
• a sheet of high permeability magnetic material closely adjacent to an extended area of said turns,
• means for insulating said conductor from said sheet,
• said sheet being heated at least in part by induction to a temperature sufficiently high to cause the permeability of the sheets to decline substantially, and
• a heat transferral member in contact with and heated by one of said sheets.

A tip construction for a heating device comprising,

• a tip of thermally and electricity conductive material,
• a rearward extension of said material of said tip,
• a layer of magnetic material disposed about in physical, thermal and electrical contact with said rearward extension,
• a coil of electrically conductive wire disposed about and in close relation to said layer whereby to induce eddy currents in said layer, and
• said close relation substantially increasing the impedance of said coil,
• means adapted to connect said coil to a source of alternating current whereby to heat said layer to a temperature sufficiently high to cause the permeability of said layer to decrease materially.

The method of utilizing a soldering iron element to melt solder comprising:

• providing a source of radio frequency current,
• passing radio frequency current from said source along a generally helical path adjacent to said element to induce current therein and heat the element,
• distorting the path of the current in said element to elongate said path in said element and thereby increase the length of the path of the current in said element whereby to increase the impedance of said helical path to said radio frequency current, and
• substantially matching the impedance of said source to said helical path,
• whereby the increased impedance of said helical path facilitates said substantial matching.