US3723862A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detector for detecting objects moving through a magnetic field established between coils of an l-c oscillator
Assignee: Siemens AG
•
Filing: 1971-04-05
•
Granted: 1973-03-27
•
Expires: 1991-04-05
Abstract
Abstract A detector for detecting objects as they move through a magnetic field established between a transmitter coil connected to an electrical supply and a receiver coil spaced from and magnetically coupled to the transmitter coil. The receiver coil, together with a capacitor, form the oscillatory circuit of an amplifier to provide an oscillator which oscillates to provide a high amplitude output signal in response to alteration of the magnetic field due to an object passing therethrough. The oscillator is provided with three feedback networks including one feedback network which functions as a source of alternating current which causes the oscillator to provide the low amplitude output signal. The oscillatory circuit includes a resistor for providing a highly damped operation which supports the effect of the first mentioned feedback circuit. A second feedback circuit provides constant amplification and a third feedback circuit includes the transmitter and receiver coils for effecting the regenerative function for oscillation.
Inventors
- 👤 P Wentzel
- 👤 E Schulze
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:50
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/945; H03K17/95; H03K17/952; H03K17/9537; H03K17/9542; H03K17/9547; C; C07; C07D; C07D201/00; C07D201/02; C07D201/04; H03K17/14
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
297 words
Apparatus for detecting objects as they move through a magnetic field, comprising: an L-C oscillator having an input and an output a transmitter coil connected to an electrical supply and to the output of said oscillator to produce a magnetic field; a receiver coil spaced from and magnetically coupled to said transmitter coil, said objects passing through the space between said coils to alter the magnetic coupling therebetween; said oscillator input connected to said receiver coil, said receiving coil constituting the inductance of the oscillator L-C circuit, said oscillator providing an output signal of a first amplitude in response to alteration of the magnetic coupling between said coils, said oscillator including first and second transistors each having a base, an emitter and a collector, the collector of said first transistor connected to the base of said second transistor, said base of said first transistor serving as said input of said oscillator and the collector-emitter circuit of said second transistor serving as the output of said oscillator; an alternating voltage source connected to said oscillator causing said oscillator to produce an output signal of a second amplitude when said magnetic coupling between said coils is unaltered, said alternating voltage source including an amplitude-dependent feedback circuit comprising a first resistor connected to the base of said first transistor, a second resistor connected between said first resistor and the collector of said second transistor and a pair of oppositely poled parallel connected diodes connected between the junction of said first and second resistors and the electrical supply for limiting the amplitude of the feedback signal; and a reverse feedback network including a third resistor connected between said emitter of said second transistor and the base of said first transistor for maintaining constant amplification for the amplifier portion of said oscillator.
Claim 2
Dependent Claim
297 words
Apparatus for detecting objects as they move through a magnetic field, comprising: an L-C oscillator having an input and an output a transmitter coil connected to an electrical supply and to the output of said oscillator to produce a magnetic field; a receiver coil spaced from and magnetically coupled to said transmitter coil, said objects passing through the space between said coils to alter the magnetic coupling therebetween; said oscillator input connected to said receiver coil, said receiving coil constituting the inductance of the oscillator L-C circuit, said oscillator providing an output signal of a first amplitude in response to alteration of the magnetic coupling between said coils, said oscillator including first and second transistors each having a base, an emitter and a collector, the collector of said first transistor connected to the base of said second transistor, said base of said first transistor serving as said input of said oscillator and the collector-emitter circuit of said second transistor serving as the output of said oscillator; an alternating voltage source connected to said oscillator causing said oscillator to produce an output signal of a second amplitude when said magnetic coupling between said coils is unaltered, said alternating voltage source including an amplitude-dependent feedback circuit comprising a first resistor connected to the base of said first transistor, a second resistor connected between said first resistor and the collector of said second transistor and a pair of oppositely poled parallel connected diodes connected between the junction of said first and second resistors and the electrical supply for limiting the amplitude of the feedback signal; and a reverse feedback network including a third resistor connected between said emitter of said second transistor and the base of said first transistor for maintaining constant amplification for the amplifier portion of said oscillator.
Claim 3
Dependent Claim
43 words
Apparatus according to claim 1, comprising a further feedback network which includes said transmitter coil connected between the electrical supply and the collector of said second transistor, and said receiver coil connected between the base of said first transistor and a reference potential.
Claim 4
Dependent Claim
43 words
Apparatus according to claim 2, comprising a capacitor connected in circuit with said receiver coil to form the L-C oscillating circuit of said oscillator, and a fourth resistor connected in circuit with said oscillatory circuit to provide strong damping of the oscillations thereof.
Claim 5
Dependent Claim
35 words
The apparatus according to claim 1, comprising a threshold circuit connected to the output of said oscillator and operable to provide an amplitude indicative signal in response to an output signal of said first amplitude.
Claim 6
Dependent Claim
68 words
The apparatus according to claim 4, comprising a voltage divider circuit connected between the emitter of said second transistor and a reference potential, and said threshold circuit comprises a third transistor having a base, an emitter and a collector, a fourth resistor connected between said voltage divider and the base of said third transistor, and a smoothing capacitor connected between the collector and emitter of sAid third transistor.
Claim 7
Dependent Claim
198 words
Apparatus for detecting objects as they move through a magnetic field, comprising: an L-C oscillator capable of operating to provide an output signal of one amplitude and of another amplitude, said oscillator having an input, an output, and an oscillatory circuit including a capacitor connected to said input and a first coil connected to said capacitor, a feedback circuit also including said first coil and a second coil connected to an electrical supply and to the output of said oscillator, said coils spaced apart and magnetically coupled, the magnetic coupling being altered by an object passing between said coils causing said oscillator to oscillate to provide said output signal at said one magnitude, an AC amplitude-dependent feedback circuit connected between the output and the input of said oscillator to cause said oscillator to oscillate to provide said output signal at said other amplitude in the absence of alteration of the magnetic coupling between said coils, and a reverse feedback circuit connected between said output and said input of said oscillator for maintaining a constant amplification of said oscillator, said oscillatory circuit including a resistor connected to said capacitor and to said first coil for strong damping of oscillations.
Claim 8
Dependent Claim
198 words
Apparatus for detecting objects as they move through a magnetic field, comprising: an L-C oscillator capable of operating to provide an output signal of one amplitude and of another amplitude, said oscillator having an input, an output, and an oscillatory circuit including a capacitor connected to said input and a first coil connected to said capacitor, a feedback circuit also including said first coil and a second coil connected to an electrical supply and to the output of said oscillator, said coils spaced apart and magnetically coupled, the magnetic coupling being altered by an object passing between said coils causing said oscillator to oscillate to provide said output signal at said one magnitude, an AC amplitude-dependent feedback circuit connected between the output and the input of said oscillator to cause said oscillator to oscillate to provide said output signal at said other amplitude in the absence of alteration of the magnetic coupling between said coils, and a reverse feedback circuit connected between said output and said input of said oscillator for maintaining a constant amplification of said oscillator, said oscillatory circuit including a resistor connected to said capacitor and to said first coil for strong damping of oscillations.
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) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |