| 摘要 |
<p>1,184,005. Semi-conductor switching circuits. MATSUSHITA ELECTRONICS CORP. 18 Aug., 1968 [31 Aug., 1967], No. 39524/68. Heading H3T. [Also in Divisions F4 and G1] In a circuit for controlling the defrosting of a refrigerator, when a thermistor 6 is cold enough, a transistor TR 1 is biased to cut-off, thereby making transistors TR 2 and TR 3 conductive and blocking a diode D2 so that when a timer (not shown) closes a switch SW to initiate defrosting, both diodes D1 and D2 are blocked, thereby making transistor TR 4 and a thyristor SG 1 conductive to allow current to flow in the defrosting circuit. TR 5 is also turned on so that bi-directional device 26 turns on SG 2 . When thermistor 6 reaches a predetermined temperature, its resistance is low enough for transistor TR 1 to be conductive and in turn to make diode D 2 conduct to bias transistors TR 4 and TR 5 into cut-off, thereby terminating the defrosting operation.</p> |
