15.18Consider a modification of the circuit of Fig. 15.23(b) in which R1 is replaced by a pair of diodes connected in parallel in opposite directions. For L+ = −L− = 12 V, R2 = R = 10 kΩ, C = 0.1 µF, and the diode voltage as a constant denoted VD, find an expression for frequency as a function of VD. If VD = 0.70 V at 25°C with a TC of –2 mV/°C, find the frequency at 0°C, 25°C, 50°C, and 100°C. Note that the output of this circuit can be sent to a remotely connected frequency meter to provide a digital readout of temperature.
f = 500/ln[(12 + VD)/(12 − VD)] Hz; 3995 Hz, 4281 Hz, 4611 Hz, 5451 Hz
![15.18Consider a modification of the circuit of Fig. 15.23(b) in which R1 is replaced by a pair of diodes connected in parallel in opposite directions. For L+ = −L− = 12 V, R2 = R = 10 kΩ, C = 0.1 µF, and the diode voltage as a constant denoted VD, find an expression for frequency as a function of VD. If VD = 0.70 V at 25°C with a TC of –2 mV/°C, find the frequency at 0°C, 25°C, 50°C, and 100°C. Note that the output of this circuit can be sent to a remotely connected frequency meter to provide a digital readout of temperature. f = 500/ln[(12 + VD)/(12 − VD)] Hz; 3995 Hz, 4281 Hz, 4611 Hz, 5451 Hz](https://i0.wp.com/electricalstudent.com/wp-content/uploads/2023/07/15.23-1.png?w=1170&ssl=1 "15.18Consider a modification of the circuit of Fig. 15.23(b) in which R1 is replaced by a pair of diodes connected in parallel in opposite directions. For L+ = −L− = 12 V, R2 = R = 10 kΩ, C = 0.1 µF, and the diode voltage as a constant denoted VD, find an expression for frequency as a function of VD. If VD = 0.70 V at 25°C with a TC of –2 mV/°C, find the frequency at 0°C, 25°C, 50°C, and 100°C. Note that the output of this circuit can be sent to a remotely connected frequency meter to provide a digital readout of temperature. f = 500/ln[(12 + VD)/(12 − VD)] Hz; 3995 Hz, 4281 Hz, 4611 Hz, 5451 Hz")
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