Abstract: A photovoltaic based heating system responsive to changing incident solar radiation using a electronic circuit and microprocessor with programming to track a point of maximum power of a photovoltaic cell array and to provide the maximum power collectively to at least one heating element without using a transformer.

Abstract: A coin operated machine, preferably a gaming machine for a casino but also including vending machines, having a removable coin collecting box and electronic memory for associating the box with the machine to enable subsequent reconciling of accounts. Both machine and box are provided with respective memory devices. The machine and the box have complementing structure for positioning the box accurately and appropriately within the machine, the structure allowing the box to be inserted reversibly. This structure comprises a tapered projection formed in the machine and cooperating, closely fitting walls surrounding the projection, formed in the box. Electrodes enabling communication between the memory devices are disposed upon contacting surfaces of the box and the projection. In alternative embodiments, the electrodes have sliding contacts, induction coils, or radio transmission apparatus for completing communication circuits.