Biochemical incubator uses potentiometer to set temperature

Shanghai Xinzhuang Instrument Co., Ltd. develops the LNB brand biochemical incubator, which is energy-saving and environmentally friendly and domestically leading. The biochemical incubator has two-way temperature regulation system for cooling and heating, and the temperature controllable function is a scientific research institution, college, production unit or department laboratory of biology, genetic engineering, medicine, health and epidemic prevention, environmental protection, agriculture, forestry and animal husbandry. The important test equipment is widely used in low temperature constant temperature test, culture test, environmental test and so on. The biochemical incubator controller circuit consists of a temperature sensor, a voltage comparator, and a control execution circuit.
Circuit principle: The circuit adopts a new temperature sensor integrated circuit ICl. The voltage comparator circuit is composed of resistors R1-R7, temperature setting potentiometers RP1, R-tooth and voltage comparator integrated circuits IC2 (N1, N2). The control execution circuit is composed of transistors V1, V2, relays K1, K2, and diodes VD1, VD2, and the like. The biochemical incubator can be restructured with an old single or double door refrigerator: use the function of the refrigerator itself to cool, install heating devices (such as electric heating wire or 150W iodine tungsten lamp) and exhaust fan under the inside of the refrigerator (can make the temperature inside the box) Evenly).

Potentiometer RPl is used to set the upper limit of temperature, and RP2 is used to set the lower limit of temperature. The relay K1 controls the heating device by heating the intermediate relay (shown in the circuit), and the relay KZ controls the refrigeration system of the refrigerator through the refrigeration intermediate relay (drawn at the end of the circuit). Pins 5 and 2 of IC2 are connected to the center plugs of RP1 and RP2 respectively. Pins 6 and 3 of IC2 are connected to the output of ICI through resistor R3. When the voltage value of pin 2 of IC2 minus the voltage value of pin 5 is approximately equal to 0·OlV, the corresponding temperature is 1 °C. When the temperature in the biochemical incubator is within the set temperature range, the voltage at pin 2 of IC2 is higher than the voltage at pin 5, and the voltage at pin 3 and pin 6 is equal to the voltage at pin 2 (or lower than pin voltage at 2 feet). Voltage), 1 pin and 7 pin output low level, VI and V2 are cut off, relay Kl, K2 are not sucked, cooling and heating circuits are not working. When the temperature inside the box exceeds the upper limit of the set temperature, the voltage of pin 3 and pin 6 of IC2 will be higher than the voltage of pin 2 and pin 5, and pin 1 of IC2 changes from low level to high level, so that V2 is turned on. The relay K2 is pulled in, its normally open contact is closed, and the refrigeration system works. When the temperature inside the box is lower than the lower limit of the set temperature, the voltage of pin 3 and pin 6 of IC2 is lower than the voltage of pin 2 and pin 5, and the pin 7 of IC2 changes from low level to high level, then Vl is turned on. The relay K1 is pulled in, its normally open contact is turned on, and the heating circuit works. The components and parts choose Rl-R5 to select 1/4W metal membrane resistor, the accuracy should be 1%; R6-R9 can choose 1/4W carbon membrane resistor. Both RPl and RP2 use a wire wound potentiometer with higher precision. C uses monolithic capacitors. Both VDl and VD2 use the 1N4148 silicon switching diode. Vl and V2 select S9013 or C8050 type silicon NPN transistor. ICl selects LM35DZ or LM36, TMP36 type temperature sensor integrated circuit; IC2 selects LM393 operational amplifier integrated circuit. Both Kl and K2 use a DC relay of l2V.
Shanghai Xinzhuang has developed low-temperature constant temperature instruments, ultrasonic instruments, box-type instruments, microbial instruments, ice-making refrigeration instruments, laboratory supporting instruments, and gradually formed a product pattern of various scientific instrument technology reserve products. Free delivery throughout the country. Reasonable price, three guarantees of quality, lifetime maintenance.

Http://