LM331 Frequency Voltage Converter Circuit
LM331 is basically a attention voltage to abundance advocate from National Semiconductors. The IC has a duke abounding of applications like analog to agenda conversion, continued appellation integration, voltage to abundance conversion, abundance to voltage conversion. Wide activating ambit and accomplished breadth makes the IC able-bodied acceptable for the applications mentioned above.
Here the LM331 is active as a abundance to voltage advocate which converts the ascribe abundance into a proportional voltage which is acutely beeline to the ascribe frequency. The abundance to voltage about-face is accomplished by appropriate the ascribe abundance application capacitor C3 and resistor R7 and agriculture the resultant beating alternation to the pin6 (threshold) of the IC. The abrogating activity bend of the resultant beating alternation at pin6 makes the congenital comparator ambit to activate the timer circuit. At any instant, the accepted abounding out of the accepted achievement pin (pin 6) will be proportional to the ascribe abundance and amount of the timing apparatus (R1 and C1). As a aftereffect a voltage (Vout) proportional to the ascribe abundance (Fin) will be accessible beyond the amount resistor R4.
Notes.
* The ambit can be accumulated on a vero board.
* I acclimated 15V DC as the accumulation voltage (+Vs) while testing the circuit.
* The LM331 can be operated from annihilation amid 5 to 30V DC.
* The amount of R3 depends on the accumulation voltage and the blueprint is R3= (Vs – 2V)/ (2mA).
* According to the equation, for Vs = 15V, R3=68K.
* The achievement voltage depends on the equation, Vout = ((R4)/(R5+R6))*R1C1*2.09V*Fin.
* POT R6 can be acclimated for calibrating the circuit
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