US3811089A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Remote engine tachometer
Assignee: Motors Liquidation Co
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Filing: 1972-07-14
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Granted: 1974-05-14
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Expires: 1992-07-14
Abstract
Abstract A tachometer which does not require connection with the engine. A probe placed near the engine picks up electromagnetic radiation produced by the distributor points and coil in bursts timed with engine speed. A bandpass filter suppresses all frequencies except a narrow band which is amplified in a circuit with automatic gain control using optic elements in the feedback loop. A reference voltage whose level is a constant fraction less than the signal maximum is produced and compared with the signal in a comparator, the output of which triggers a one shot pulse generator to produce a train of pulses of constant width and amplitude at a frequency proportional to engine speed.
Inventors
- 👤 A Strzelewicz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:02
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/4802; G01P3/4807
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
250 words
A tachometer for an engine, said engine having an electric ignition system radiating bursts of electromagnetic signals at a rate proportional to the rate of engine rotation, the tachometer comprising, in combination: means effective to receive electromaGnetic signals radiated by the engine; a bandpass filter connected to the output of the electromagnetic signal receiving means, the bandpass filter passing only signals having frequencies within a narrow band in the audio range; signal amplification means amplifying the output of the bandpass filter, the signal amplification means including an amplifier with a negative feedback loop, the negative feedback loop containing a variable resistor; a peak memory circuit responsive to the output of the signal amplification means and operative to generate a DC voltage proportional to the peak amplitude of the output of the signal amplification means; filter means connected to the output of the peak memory circuit to smooth the DC voltage output thereof; means responsive to the output of the filter means to vary the resistance of the variable resistor so as to stabilize the output of the signal amplification means; voltage attenuating means responsive to the output of the peak memory circuit and operative to attenuate this output by a fixed fraction; a comparator operative to compare the output of the signal amplification means with the output of the voltage attenuating means and generate an output signal when the former exceeds the latter; and means to generate a pulse of constant duration each time the comparator produces an output signal.
Claim 2
Dependent Claim
250 words
A tachometer for an engine, said engine having an electric ignition system radiating bursts of electromagnetic signals at a rate proportional to the rate of engine rotation, the tachometer comprising, in combination: means effective to receive electromaGnetic signals radiated by the engine; a bandpass filter connected to the output of the electromagnetic signal receiving means, the bandpass filter passing only signals having frequencies within a narrow band in the audio range; signal amplification means amplifying the output of the bandpass filter, the signal amplification means including an amplifier with a negative feedback loop, the negative feedback loop containing a variable resistor; a peak memory circuit responsive to the output of the signal amplification means and operative to generate a DC voltage proportional to the peak amplitude of the output of the signal amplification means; filter means connected to the output of the peak memory circuit to smooth the DC voltage output thereof; means responsive to the output of the filter means to vary the resistance of the variable resistor so as to stabilize the output of the signal amplification means; voltage attenuating means responsive to the output of the peak memory circuit and operative to attenuate this output by a fixed fraction; a comparator operative to compare the output of the signal amplification means with the output of the voltage attenuating means and generate an output signal when the former exceeds the latter; and means to generate a pulse of constant duration each time the comparator produces an output signal.
Claim 3
Dependent Claim
496 words
A tachometer for indicating the rotational speed of an engine having an electrical ignition system radiating bursts of electromagnetic signals at a rate proportional to the rate of engine rotation, the tachometer comprising, in combination: an electromagnetic signal sensing probe; a bandpass filter connected to said probe, the bandpass filter being tuned to a frequency in the audio range; a first capacitor having one end connected to the output of the bandpass filter; a first operational amplifier having an output, a grounded non-inverting input and an inverting input connected through an input resistor to the other end of the first capacitor; first and second resistors in parallel connecting the output and inverting input of the first operational amplifier, the first resistor having a resistance varying inversely with light intensity; a third resistor having one end connected to the output of the first operational amplifier; a first forward biased diode having an input connected to the other end of the third resistor; a second capacitor and fourth resistor connected between the output of the first forward biased diode and ground; a second operational amplifier having an output, an inverting input and a non-inverting input connected to the output of the first forward-biased diode; a second forward-biased diode having an input connected to the output of the second operational amplifier and an output connected to the inverting input of the second operational amplifier; a fifth resistor having one end connected to the output of the second operational amplifier; a sixth resistor and third capacitor connected between the other end of the fifth resistor and ground, the sixth resistor having a variable resistance tap; an NPN transistor having a base connected to the variable resistance tap of the sixth resistor, a collector and an emitter; a constant voltage source connected to the collector of the NPN transistor; a seventh resistor connecting the emitter and collector of the NPN transistor; a lamp physically adjacent the first resistor, the lamp being connected between the emitter of the transistor and ground; an eighth resistor connected between the output of the second operational amplifier and ground, the eighth resistor having a variable resistance tap; a comparator having an output, an inverting input and a non-inverting input; a third forward biased diode having an input connected to the variable tap of the eighth resistor and an output connected to the non-inverting input of the comparator; niNth and tenth resistors connected in series between the constant voltage source and ground; an eleventh resistor connecting the junction of the ninth and tenth resistors with the non-inverting input of the comparator; a fourth forward-biased diode connecting the output of the first operational amplifier with the inverting input of the comparator; a fourth capacitor having one end connected to the output of the comparator; and a pulse generator having an input connected to the other end of the fourth capacitor and an output at which is produced a train of pulses at a frequency proportional to engine rotation.
Claim 4
Dependent Claim
496 words
A tachometer for indicating the rotational speed of an engine having an electrical ignition system radiating bursts of electromagnetic signals at a rate proportional to the rate of engine rotation, the tachometer comprising, in combination: an electromagnetic signal sensing probe; a bandpass filter connected to said probe, the bandpass filter being tuned to a frequency in the audio range; a first capacitor having one end connected to the output of the bandpass filter; a first operational amplifier having an output, a grounded non-inverting input and an inverting input connected through an input resistor to the other end of the first capacitor; first and second resistors in parallel connecting the output and inverting input of the first operational amplifier, the first resistor having a resistance varying inversely with light intensity; a third resistor having one end connected to the output of the first operational amplifier; a first forward biased diode having an input connected to the other end of the third resistor; a second capacitor and fourth resistor connected between the output of the first forward biased diode and ground; a second operational amplifier having an output, an inverting input and a non-inverting input connected to the output of the first forward-biased diode; a second forward-biased diode having an input connected to the output of the second operational amplifier and an output connected to the inverting input of the second operational amplifier; a fifth resistor having one end connected to the output of the second operational amplifier; a sixth resistor and third capacitor connected between the other end of the fifth resistor and ground, the sixth resistor having a variable resistance tap; an NPN transistor having a base connected to the variable resistance tap of the sixth resistor, a collector and an emitter; a constant voltage source connected to the collector of the NPN transistor; a seventh resistor connecting the emitter and collector of the NPN transistor; a lamp physically adjacent the first resistor, the lamp being connected between the emitter of the transistor and ground; an eighth resistor connected between the output of the second operational amplifier and ground, the eighth resistor having a variable resistance tap; a comparator having an output, an inverting input and a non-inverting input; a third forward biased diode having an input connected to the variable tap of the eighth resistor and an output connected to the non-inverting input of the comparator; niNth and tenth resistors connected in series between the constant voltage source and ground; an eleventh resistor connecting the junction of the ninth and tenth resistors with the non-inverting input of the comparator; a fourth forward-biased diode connecting the output of the first operational amplifier with the inverting input of the comparator; a fourth capacitor having one end connected to the output of the comparator; and a pulse generator having an input connected to the other end of the fourth capacitor and an output at which is produced a train of pulses at a frequency proportional to engine rotation.
Claim 5
Dependent Claim
18 words
The tachometer of claim 2 in which the bandpass filter is tuned to a frequency of 10.5 KHz.
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) | 1977-05-13 | 1977-11-12 | 1978-05-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-13 | 1981-11-12 | 1982-05-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-13 | 1985-11-12 | 1986-05-14 | $7700.00 | Window Closed / Lapsed |