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实验室常用的各式电热烘箱,一般采用电子继电器作恒温控制。当供电电压降至180伏以下时,继电器由于线圈电流太小而吸力减弱,触点闭合不全,常因火花熔蚀粘连,导致控制失灵,很不可靠。我们用可控硅作无触点开关来代替电子继电器,对一台600瓦 HH·B·11型电热恒温培养箱的控温装置作了改造。从1977年11月投入使用,迄今已连续使用三年多,证明性能可靠,无论供电电压怎样波动,可控硅均能正常工作,新装置只需两只可控硅和两只、二极管,都是固体元件,结构牢固,无火花,经久耐用。这个装置的电路如下图所示,原理参考《无线电杂志》1976年第3、9期。
Laboratory commonly used various types of electric oven, the general use of electronic relays for temperature control. When the supply voltage drops below 180 volts, the relay due to the coil current is too small and the suction weakened, contact closure is not complete, often due to spark erosion adhesion, resulting in control failure, it is not reliable. We use SCR as a non-contact switch instead of electronic relays, on a 600-watt HH · B · 11 type thermostatic incubator temperature control device has been modified. From November 1977 put into use, so far has been more than three years of continuous use, proven reliable performance, no matter how the supply voltage fluctuations, SCR can work normally, the new device only two SCR and two diodes Solid components, solid structure, no sparks, durable. The circuit of this device is shown in the following figure. The principle is referred to “Radio Magazine” No. 3 and No. 9, 1976.