Honeywell International Inc.

Ademco Inc.

Daniel Landry

Daniel Tousignant

Alex Daher

Evelyne Tremblay

Lionel Bravard

Marco Lussier

Joel McNabb-Baltar

A power supply unit for use with thermostats or other like devices requiring power. A power supply unit may be designed to keep electromagnetic interference emissions at a minimum, particularly at a level that does not violate governmental regulations. A unit may be designed so that there is enough power for a triggering a switch at about a cross over point of a waveform of input power to the unit. Power for triggering may come from a storage source rather than line power to reduce emissions on the power line. Power for the storage source may be provided with power stealing. Power stealing may require switching transistors which can generate emissions. Gate signals to the transistors may be especially shaped to keep emissions from transistor switching at a minimum.

Triac or bypass circuit and MOSFET power steal combination

Active triac triggering circuit

A line voltage thermostat having a multiple heatsink switch. A total switch may have a semiconductor switch mounted on each heatsink of the multiple heatsink switch. The semiconductor switches of the respective heatsinks may be connected in parallel to represent the total switch. Each of the two or more heatsinks, having a semiconductor switch for switching, and in total conveying the same power as one equivalent switch with one total heatsink, may have higher maximum operating temperatures and higher thermal resistances than twice the thermal resistance of the one total heatsink. The two or more heatsinks may be situated within a housing of the line voltage thermostat, and be easier to distribute in the housing to achieve an efficient layout of a display and control buttons for the thermostat.

Multiple heatsink cooling system for a line voltage thermostat

A circuit that may control current to a load without generating a large amount of electromagnetic interference on main lines of an AC power supply for the load and circuit. Control may be effected with silicon controlled rectifiers (SCRs). For instance, the circuit may implement passive triggering using a capacitor between the anode and the gate of an SCR. By using a sufficiently large capacitor, gate current may be applied during a zero crossing of a waveform of the AC power supply in a passive manner without a need to store energy prior to the zero crossing. The circuit may synchronize SCR triggering with a voltage variation in a clean manner, that is, without generating electromagnetic interference. The circuit may be used with an in-line thermostat. However, the circuit may be used in other ways.

Passive drive control circuit for AC current

MOSFET gate driving circuit for transition softening

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St-Hyacinthe, Canada

Daniel Landry