Using the thermistor characterized in the data sheet, and a 555 integrated circuit as a threshold detector, design a circuit to light an LED when the tempreature exceeds 80°C. Draw a circuit diagram with component values marked on it. Estimate the temperature at which the LED would turn off (correct answer attached).
Now what I want to know is:
*How do you know that the supply rail = 9V?
*How do you calculate R = 8K?
I know that you are suppose to use Vout = V.Rth / Rth + R but only knew that Rth ≈ 3.8k when the temperature = 80°C.
Now what I want to know is:
*How do you know that the supply rail = 9V?
*How do you calculate R = 8K?
I know that you are suppose to use Vout = V.Rth / Rth + R but only knew that Rth ≈ 3.8k when the temperature = 80°C.
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