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
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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