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Beat Frequency Monitor

IP.com Disclosure Number: IPCOM000097187D
Original Publication Date: 1962-Jun-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Clapper, GL: AUTHOR

Abstract

The circuitry produces a direct voltage out put as a linear function of a variable frequency input. The latter is applied at 10 with an amplitude of between two and twenty volts. The signal is amplified by transistor 11 and overdrives transistor 12 to produce a clipped output across resistor 9. This output is essentially a square wave, well-suited to differentation. The positive transient of this essentially square wave output is clamped to -6 volts by diode 13.

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Beat Frequency Monitor

The circuitry produces a direct voltage out put as a linear function of a variable frequency input. The latter is applied at 10 with an amplitude of between two and twenty volts. The signal is amplified by transistor 11 and overdrives transistor 12 to produce a clipped output across resistor 9. This output is essentially a square wave, well-suited to differentation. The positive transient of this essentially square wave output is clamped to -6 volts by diode 13.

The negative output transient acts through diode 14 to turn on a monostable multivibrator consisting of transistors 15 and 16 which function as a shaper for the output of transistor 12. The output of multivibrator 15, 16 is applied to integrator 17, 18. The latter controls transistor 19 to generate an output voltage at 20. This is a function of the input frequency and the value of capacitor 21.

Linearization of the output is effected by feedback through resistor 22. At the low or middle frequencies, output 20 is low. Current flows from the output through resistor 22 to one side of capacitor 21, through resistor 23 to the base of transistor 15. This tends to shorten the time that 15 is cut off and shorten the time 16 is conducting.

As the output increases negatively, resistor 22 conducts less current and the pulse output from multivibrator 15, 16 gets longer. By varying the value of capacitor 21, the range of operation of the circuit is varied.

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