| 摘要 |
<p>882,215. Control systems for heating resistors. USINES & FOUNDERIES A. MARTIN. Sept. 8, 1958 [Sept. 7, 1957; June 24, 1958], No. 28746/58. Class 38 (4). A temperature controller for an electric hotplate controlled by a thermal cycling switch 1, 3-5 has a replaceable negative temperature coefficient resistor 2 in thermal relation with the heater element 10 and in series with the heater 5 of the cycling switch so that as the temperature of the element increases, the resistance of the negative temperature resistor is reduced, hence reducing the average current to the heating element. An additional resistor may be placed in parallel with the heater 5 to adjust its characteristics. In an alternative arrangement a manually adjustable resistor 20 is placed in series with resistor 5, and the element 10 may be in two parts so that one part may be short circuited by a switch 21. Indicator lamps 16, 17 may also be provided.</p> |
