MULTI FREQUENCY MASS SPRING OSCILLATORS

• US 3,742,387 A
• Filed: 12/08/1971
• Issued: 06/26/1973
• Est. Priority Date: 12/08/1971
• Status: Expired due to Term

• Current Assignee: Manfred Davis
• Original Assignee: Manfred Davis
• Inventors: Davis, Manfred
• Primary Examiner(s): Lake, Roy
• Assistant Examiner(s): Grimm, Siegfried H.
• Application Number:
  US05/205,873
• Time in Patent Office: 566 Days
• Field of Search: 331/116M,156,179,182 310/25 318/128 84/DIG.21
• US Class Current: 331/156
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator
• CPC Class Codes: Y10S 84/21 Mechanical resonator

Abstract

A multi frequency signal generator employing a cantilever beam comb wherein each beam has a different natural vibration frequency. The beams are selectively coupled through capacitive pickups to frequency modulate a high frequency oscillator. The modulated oscillator frequency is passed through a frequency discriminator, and the amplified output of the discriminator supplies the signal generator output and also is applied to a magnetic drive circuit for sustaining the selected beam in vibration at its natural frequency.

Claims

1. A device for generating electrical signals and audible tones of constant frequency comprising a cantilever beam comb, made of a material of high modulus of elasticity and made in such a manner as to render the tips of each beam magnetic, mounted to an innertial block and acted upon by a magnetic field produced by an electromagnet, a multi-element capacitance probe, one element corresponding to each beam of the comb, mounted in proximity to the beams for detecting the motion of the beams, a selector switch which allows electrical contact to be made to any of the elements of the capacitance probe, an electronic module containing an R.F. oscillator which operates in conjunction with the selected probe element to produce a frequency which varies as the corresponding beam of the comb moves, a frequency discriminator with center frequency corresponding to the center frequency of the R.F. oscillator which converts the frequency of the oscillator into a driving signal for a power amplifier and electromagnet, a voltage amplifier and compression circuit which is connected between the frequency discriminator and power amplifier providing voltage dependent gain such that when the vibration level of the selected beam is small the gain of the amplifier is high and as the vibration level of the beam increases the gain of the amplifier decreases, and a buffer amplifier which provides a low output impedance for the connection of a load.

2. A device As described in claim 1 which has increased frequency stability, wherein the cantilever beam comb and capacitance probe are contained in a constant temperature enclosure.

3. A device as described in claim 2 which has further improvement in frequency stability by the use of materials which have a low coefficient of thermal expansion for the cantilever beam comb, and in the event that such material is non-magnetic, having small magnetic pads attached to the end of each of the cantilever beams in proximity to the electromagnet.

4. A device as described in claim 1 which in order to reduce cost at some compromise of frequency stability has the cantilever beam made entirely out of magnetic spring steel.