Temperature indicator electronic circuit using LEDs

An temperature indicator electronic circuit can be designed using electronic diagram below. Temperature circuit uses only the following three integrated circuits, a temperature sensor LM335, LM723 voltage regulator and a level detector with five analog outputs, TL489.
Temperature sensor (IC1) is supplied with a steady stream of reference to the output of LM723 (IC2). This ensures a stable zero point allowing the claim is very accurate. Parts around 723 are thus chosen to allow the regulator output to vary between zero volts and a volt.
It acts as an amplifier with a gain of 26 dB effective. The output level is coupled to the analog input of IC3. Depending on the input voltage, the integrated circuit will turn on one or more of the LEDs D1 ... D5. Since the sensor sensitivity is 10 mV per degree Celsius (10 mV / ° C) and amplification of 723 is 20 times. Means TL489 needs a 200 mV increase in the level of the entry to turn one LED light. For each degree increase in temperature will light an LED.
Temperature range is set by potentiometer P1de example 18 ... 23 ° C (5 ° C). This range can be changed as desired, simply by changing the resistance values of R6 and R7. To light an LED to a variation of two degrees, the resistance values should be 100 K.