The technical principle of the biochemical incubator The temperature sensor circuit uses 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 circuit 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 of pin 2 of IC2 is higher than the voltage of pin 5, and the voltage of pin 3 and pin 6 is equal to the voltage of pin 2 (or lower than the voltage of pin 2 and higher than 5 feet). Voltage), 1 pin and 7 pin output low level, VI and V2 are cut off, relay Kl, K2 are not attracted, cooling and heating circuits are not working. Safty Pe Plaster,Allroundprinted Plaster,Multi Size Plaster,Bee Patches Plaster RFX+CARE Manufacturing Co.,Ltd. , https://www.rk-rfxcare.com
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.