US3602626A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic music keying circuit with diode and capacitor for reducing leakage current
Assignee: Nippon Gakki Co Ltd
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Filing: 1969-09-24
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Granted: 1971-08-31
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Expires: 1989-09-24
Abstract
Abstract An improved transistor keying circuit for use in electronic musical instruments to help minimize leakage of signals therethrough even when the circuit is in an off condition as is often caused by interelectrode transistor capacitances. The improved circuit utilizes a diode connected in series with a load resistor to a transistor collector or emitter electrode in a direction that permits collector-emitter current to flow normally in the forward direction thus permitting normal circuit operation when in an ''''on'''' condition. A capacitor is effectively shunt connected across the diode and load resistor with the output being taken from the junction of the load resistor and diode. Since the capacitor has a large capacitance as compared with the base-collector or base-emitter capacitance, leakage signals in the ''''off'''' state are effectively shunted to ground to greatly reduce the level of any leakage to the output terminal.
Inventors
- 👤 Kazuyuki Aramaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:31
CPC Classifications
G; G10; G10H; G10H1/00; G10H1/18; Y; Y10; Y10S; Y10S84/00; Y10S84/07
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
216 words
An improved transistor switching circuit for use in electrical musical instruments and which minimizes undesired leakage of signals from an input terminal to an output terminal in an off state due to internal interelectrode capacitances of the switching transistor, said improved circuit comprising: at least one switching transistor having an input electrode and an output electrode with interelectrode capacitance therebetween, an input terminal for receiving input signals, an output terminal for providing an output signal corresponding to said input signal when said circuit is switched on, a diode connected to said output electrode with a forward diode current direction corresponding to forward collector-emitter current in said transistor to insure normal switching operation when the circuit is switched on for passing signals from said input terminal to the output terminal but which offers a relatively large impedance when the circuit is switched off, a load resistor series connected with said diode at a junction point, said output terminal being connected to said junction point, and a capacitor having a large capacitance as compared to said interelectrode capacitance, said capacitor being effectively shunt connected across said series connected diode and resistor thereby effectively minimizing undesired leakage of signals to the output terminal in the off state of said circuit by shunting such signals away from the output terminal.
Claim 2
Dependent Claim
216 words
An improved transistor switching circuit for use in electrical musical instruments and which minimizes undesired leakage of signals from an input terminal to an output terminal in an off state due to internal interelectrode capacitances of the switching transistor, said improved circuit comprising: at least one switching transistor having an input electrode and an output electrode with interelectrode capacitance therebetween, an input terminal for receiving input signals, an output terminal for providing an output signal corresponding to said input signal when said circuit is switched on, a diode connected to said output electrode with a forward diode current direction corresponding to forward collector-emitter current in said transistor to insure normal switching operation when the circuit is switched on for passing signals from said input terminal to the output terminal but which offers a relatively large impedance when the circuit is switched off, a load resistor series connected with said diode at a junction point, said output terminal being connected to said junction point, and a capacitor having a large capacitance as compared to said interelectrode capacitance, said capacitor being effectively shunt connected across said series connected diode and resistor thereby effectively minimizing undesired leakage of signals to the output terminal in the off state of said circuit by shunting such signals away from the output terminal.
Claim 3
Dependent Claim
168 words
A keying circuit for use in electronic musical instruments, said circuit comprising: an input terminal; an output terminal; a transistor and a load resistor constituting an amplifier circuit, one electrode of said transistor effectively being an input electrode and another electrode of said transistor effectively being an output electrode, a key switch connected in said amplifier circuit at a position where closing and opening of said key switch renders said amplifier operative and nonoperative, a diode connecTed in series between said load resistor and said output electrode in such a direction as to permit the normal forward transistor current to also flow in the forward direction of said diode; and a capacitor connected between said output electrode and a constant potential terminal, said capacitor having a substantially large capacitance than the internal capacitance between said input electrode and said output electrode of said transistor; said input terminal being connected to said input electrode and said output terminal being connected to the juncture of said diode and load resistor.
Claim 4
Dependent Claim
168 words
A keying circuit for use in electronic musical instruments, said circuit comprising: an input terminal; an output terminal; a transistor and a load resistor constituting an amplifier circuit, one electrode of said transistor effectively being an input electrode and another electrode of said transistor effectively being an output electrode, a key switch connected in said amplifier circuit at a position where closing and opening of said key switch renders said amplifier operative and nonoperative, a diode connecTed in series between said load resistor and said output electrode in such a direction as to permit the normal forward transistor current to also flow in the forward direction of said diode; and a capacitor connected between said output electrode and a constant potential terminal, said capacitor having a substantially large capacitance than the internal capacitance between said input electrode and said output electrode of said transistor; said input terminal being connected to said input electrode and said output terminal being connected to the juncture of said diode and load resistor.
Claim 5
Dependent Claim
49 words
A keying circuit according to claim 2 wherein: said transistor comprises an emitter-grounded amplifier, said input electrode is a base electrode of said transistor, said output electrode is a collector electrode of said transistor, and said key switch is connected in series in the emitter path of said transistor.
Claim 6
Dependent Claim
49 words
A keying circuit according to claim 2 wherein: said transistor constitutes a base-grounded amplifier, said input electrode is an emitter electrode of said transistor, said output electrode is a collector electrode of said transistor, and said key switch is connected in series in the base path of said transistor.
Claim 7
Dependent Claim
49 words
A keying circuit according to claim 2 wherein: said transistor constitutes a collector-grounded amplifier, said input electrode is a base electrode of said transistor, said output electrode is an emitter electrode of said transistor, and said key switch is connected in series in the emitter path of said transistor.
Claim 8
Dependent Claim
191 words
A keying circuit for use in electronic musical instruments, said circuit comprising: a plurality of input terminals; a common output terminal; a plurality of transistors and a common load resistor comprising common load amplifiers, one electrode of each of said transistors effectively being an output electrode, a second electrode of each of said transistors effectively being an input electrode, a plurality of key switches each being connected in each of said plurality of amplifier circuits at a position where closing and opening of said each key will render its associated amplifier operative and nonoperative, a diode connected in series between said common load resistor and said output electrodes in such a direction as to permit normal forward transistor currents to also flow in the forward direction of said diode; and a common capacitor connected between said output electrodes and a constant potential and having a substantially larger capacitance than the internal capacitance between said input electrode and said output electrode of one of said transistors; said input terminals being connected to said input electrodes, and said common output terminal being connected to the juncture between said diode and said load resistor.
Claim 9
Dependent Claim
191 words
A keying circuit for use in electronic musical instruments, said circuit comprising: a plurality of input terminals; a common output terminal; a plurality of transistors and a common load resistor comprising common load amplifiers, one electrode of each of said transistors effectively being an output electrode, a second electrode of each of said transistors effectively being an input electrode, a plurality of key switches each being connected in each of said plurality of amplifier circuits at a position where closing and opening of said each key will render its associated amplifier operative and nonoperative, a diode connected in series between said common load resistor and said output electrodes in such a direction as to permit normal forward transistor currents to also flow in the forward direction of said diode; and a common capacitor connected between said output electrodes and a constant potential and having a substantially larger capacitance than the internal capacitance between said input electrode and said output electrode of one of said transistors; said input terminals being connected to said input electrodes, and said common output terminal being connected to the juncture between said diode and said load resistor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-30 | 1975-03-01 | 1975-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-30 | 1979-03-01 | 1979-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-30 | 1983-03-01 | 1983-08-31 | $7700.00 | Window Closed / Lapsed |