Temperature alarm device
CA 1084141 A · Owner: Davies, Thomas · Inventors: Davies, Thomas
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An audible alarm device for use primarily with domestic freezers to provide an audible warning system as a malfunction of the freezer is disclosed. The device comprises a sensor circuit including a Wheatstone bridge having a negative temperature coefficient thermistor in one branch, and a high gain differential amplifier to sense voltage differential across the bridge and a, transistor between the amplifier and an audible signal device. A primary power source normally powers the circuit with low voltage direct current from a transformer having a rectified secondary winding, and the device also has a secondary power source of low voltage direct current which comprises a battery providing …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted August 19, 1980. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended August 19, 1997.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.