Temperature Indicator Schematic Diagram

Parts List:
    R1 = 10K                    IC1 = CA3240E
    R2 = Thermistor      Led1,2,3,4 = Led's of your choice
 R3-R7 = 5K                     BZ1 = Buzzer, 6V
R8-R11 = 220 ohm                 B1 = battery, 9V


This circuit sets off a buzzer after the last Led (led4) is lit.  It is a 
simple but fun circuit to experiment with.  You can replace the buzzer with 
something else, add a trimpot to adjust sensitivity, etc, etc. The possibilities 
are endles.

The CD3240E IC may in some cases be difficult to obtain.

Try the following resources below:

Digikey order #CA3240EZ-ND  $2.04
Newark order #CA3240E  $2.80

Have fun building or bread-boarding this circuit and don't hesitate to 
experiment on it!

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