US3795169A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic device employing a phase locked loop for tuning musical instruments
Assignee: SIGNA SIGNER Inc
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Filing: 1973-05-31
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Granted: 1974-03-05
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Expires: 1993-05-31
Abstract
Abstract An electronic tuner is used to indicate when a musical instrument is tuned above or below a desired given frequency. The disclosed elctronic tuner includes the following elements in series: an audio frequency microphone, a band pass filter selected to the frequency range desired, a preamplifier, a phase locked loop with associated power supply for detecting when the incoming frequency is above or below the desired frequency, an output amplifier, and a push-pull complementary transistor output means for driving a pair of lamps in such a fashion as to indicate whether the incoming frequency is above or below the desired frequency. Frequency discrimination is performed by the phase locked loop which is adjusted to a normal B concert frequency of 466.2 Hz. The discriminating range of the phase locked loop may be varied according to the requirements of the instrument.
Inventors
- 👤 D Belcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 00:38
CPC Classifications
G; G10; G10G; G10G7/00; G10G7/02; G10H; G10H1/00; G10H1/44
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
142 words
An electronic tuning device for aiding in tuning a musical instrument, comprising; an input circuit for receiving a signal having a frequency in the musical range, a phase locked loop circuit responsive to said input circuit and having an output, said phase locked loop circuit including a reference frequency oscillator for generating a reference center frequency, a phase detector for receiving said signal and providing an output proportional to the difference between said signal frequency and said center frequency, and a feedback loop from said detector to said oscillator for driving said oscillator to said signal frequency, a power supply circuit means connected to said phase locked loop circuit for providing power thereto, and an output circuit means connected to said phase locked loop output and including a visual indicator for indicating when said signal is above or below said center frequency.
Claim 2
Dependent Claim
142 words
An electronic tuning device for aiding in tuning a musical instrument, comprising; an input circuit for receiving a signal having a frequency in the musical range, a phase locked loop circuit responsive to said input circuit and having an output, said phase locked loop circuit including a reference frequency oscillator for generating a reference center frequency, a phase detector for receiving said signal and providing an output proportional to the difference between said signal frequency and said center frequency, and a feedback loop from said detector to said oscillator for driving said oscillator to said signal frequency, a power supply circuit means connected to said phase locked loop circuit for providing power thereto, and an output circuit means connected to said phase locked loop output and including a visual indicator for indicating when said signal is above or below said center frequency.
Claim 3
Dependent Claim
27 words
The apparatus of claim 1 wherein said reference frequency oscillator is a voltage control oscillator having an adjustable free running frequency corresponding to said reference center frequency.
Claim 4
Dependent Claim
16 words
The apparatus of claim 2 wherein the free-running frequency of said voltage control oscillator is 466.2Hz.
Claim 5
Dependent Claim
27 words
The apparatus of claim 1 wherein said phase locked loop circuit includes a capture adjust circuit for determining the band of acquisition of said phase locked loop.
Claim 6
Dependent Claim
36 words
The apparatus of claim 1 wherein said input circuit includes a microphone means connected in series with a band pass filter and an amplifier, said band pass filter being tuned to pass said musical frequency signal.
Claim 7
Dependent Claim
59 words
The apparatus of claim 1 wherein said phase looked loop further includes, an amplifier having an input and an output, the input of said amplifier being connected to the output of said phase detector and the output of said amplifier being connected to the output of said phase locked loop and to the input of said reference frequency oscillator.
Claim 8
Dependent Claim
22 words
The apparatus of claim 6 wherein said amplifier produces a pair of voltage outputs proportional to the output of said phase detector.
Claim 9
Dependent Claim
58 words
The apparatus of claim 7 wherein said output circuit means includes a differential amplifier having a pair of input terminals each connected to receive said voltage outputs from said phase locked loop amplifier, said differential amplifier including an output terminal, and wherein said visual indicator has an input terminal connected to the output terminal of said differential amplifier.
Claim 10
Dependent Claim
114 words
The apparatus of claim 8 wherein said visual indicator comprises, an NPN transistor having a base, collector, and emitter, a PNP transistor having a base, collector, and emitter, the bases of both of said transistors being connected together and forming said visual indicator input terminal and the emitters of both of said transistors being connected together to a common ground, a pair of lamps, a positive lamp power supply, and a negative lamp power supply, wherein one of said lamps is connected between the collector of said NPN transistor and said positive power supply and the other of said lamps is connected between the collector of said PNP transistor and said negative power supply.
Claim 11
Dependent Claim
36 words
The apparatus of claim 1 wherein said power supply circuit means is a regulated power supply including a pair of cross-coupled amplifiers for producing a pair of positive and negative voltages for said phase locked loop.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |