US3643115A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interface circuit for industrial control systems
Assignee: Allen Bradley Co LLC
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Filing: 1970-02-19
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Granted: 1972-02-15
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Expires: 1990-02-19
Abstract
Abstract One contact of a controlling device connects to the input terminal of an industrial control system and the other contact connects to a positive voltage source through a blocking diode and to a high-voltage source through a resistor. A transistor collector is connected to the input terminal of the control system, and a feedback resistor connects its emitter to a negative voltage source. A bias current supplied to the base of the transistor saturates it. When the controlling device contacts close, the high-voltage source applied across them insures that conduction is established. Current then flows through the transistor resulting in a feedback action which brings the transistor out of saturation. The voltage on the transistor''s collector and the input terminal to the industrial control system then rises to the potential of the positive voltage source.
Inventors
- 👤 William W Kiffmeyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:41
CPC Classifications
H; H03; H03K; H03K19/00; H03K19/0175; H03K19/018; H03K19/01825; G; G05; G05B; G05B19/00; G05B19/02; G05B19/04
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
127 words
An interface circuit for connecting a controlling device to a controlled system the combination comprising: a current amplifier having an input connection, a common connection and an output connection, said output connection adapted to connect with a first terminal on the controlling device and a first terminal on the controlled system; a bias current source connected to the input connection of said current amplifier and adapted to supply sufficient bias current to saturate said current amplifier; a feedback network connected between the common connection of said current amplifier and said bias current source such that the controlling device controls current flow through said current amplifier and feedback network, and the current flow through said feedback network operates to decrease the bias current supplied to said current amplifier.
Claim 2
Dependent Claim
127 words
An interface circuit for connecting a controlling device to a controlled system the combination comprising: a current amplifier having an input connection, a common connection and an output connection, said output connection adapted to connect with a first terminal on the controlling device and a first terminal on the controlled system; a bias current source connected to the input connection of said current amplifier and adapted to supply sufficient bias current to saturate said current amplifier; a feedback network connected between the common connection of said current amplifier and said bias current source such that the controlling device controls current flow through said current amplifier and feedback network, and the current flow through said feedback network operates to decrease the bias current supplied to said current amplifier.
Claim 3
Dependent Claim
20 words
The interface circuit of claim 1 wherein: the current amplifier is a transistor and the feedback network is a resistor.
Claim 4
Dependent Claim
39 words
The interface circuit of claim 2 wherein: a blocking diode is connected between a second terminal on the controlling device and a positive voltage source, and a high-voltage resistor is connected between said second terminal and a high-voltage source.
Claim 5
Dependent Claim
20 words
The interface circuit of claim 1 wherein: said feedback network is comprised of a resistor and a negative voltage source.
Claim 6
Dependent Claim
28 words
The combination of claim 4 wherein: there is a clamping diode connected between said input connection to said current amplifier and a second terminal on said controlled system.
Claim 7
Dependent Claim
124 words
An interface circuit for connection between a controlling device and a controlled system the combination comprising: a blocking diode connected between a voltage source and a first terminal on said controlling device; a high-voltage resistor connected between a high-voltage source and said first terminal on the controlling device; and a voltage developing device having a common connection to a second terminal on said controlling device and a first terminal on the controlled system, and connected across the first and second input terminals of the controlled system; whereby said voltage developing device applies substantially zero voltage across said input terminals when no current flows through said controlling device, and develops a voltage limited by said voltage source when a current flows through said controlling device.
Claim 8
Dependent Claim
124 words
An interface circuit for connection between a controlling device and a controlled system the combination comprising: a blocking diode connected between a voltage source and a first terminal on said controlling device; a high-voltage resistor connected between a high-voltage source and said first terminal on the controlling device; and a voltage developing device having a common connection to a second terminal on said controlling device and a first terminal on the controlled system, and connected across the first and second input terminals of the controlled system; whereby said voltage developing device applies substantially zero voltage across said input terminals when no current flows through said controlling device, and develops a voltage limited by said voltage source when a current flows through said controlling device.
Claim 9
Dependent Claim
75 words
The interface circuit of claim 6 wherein: the voltage developing device is a transistor having its collector connected to the second terminal of said controlling device and the first input terminal of said controlled system, a feedback network connected between the emitter of said transistor and the second input terminal of said controlled system, and a bias current supply connected between the base of said transistor and the second input terminal of said controlled system.
Claim 10
Dependent Claim
15 words
The interface circuit of claim 7 wherein: said feedback network is comprised of a resistor.
Claim 11
Dependent Claim
20 words
The interface circuit of claim 7 wherein: said feedback network is comprised of a resistor and a negative voltage source.
Claim 12
Dependent Claim
28 words
The interface circuit of claim 9 wherein: there is a clamping diode connected between the base of said switching transistor and the second input to the controlled system.
Claim 13
Dependent Claim
99 words
An interface circuit for connecting first and second terminals on a controlling device to first and second terminals of a controlled device, the combination comprising: a transistor having its collector connected to the first terminals on said controlling and controlled devices; a feedback resistor connected between the emitter of said transistor and the second terminal of said controlled device; a bias current supply connected between the base of said transistor and the second terminal of said controlled device; and a voltage source connected between the second terminal of said controlling device and the second terminal of said controlled device.
Claim 14
Dependent Claim
99 words
An interface circuit for connecting first and second terminals on a controlling device to first and second terminals of a controlled device, the combination comprising: a transistor having its collector connected to the first terminals on said controlling and controlled devices; a feedback resistor connected between the emitter of said transistor and the second terminal of said controlled device; a bias current supply connected between the base of said transistor and the second terminal of said controlled device; and a voltage source connected between the second terminal of said controlling device and the second terminal of said controlled device.
Claim 15
Dependent Claim
39 words
An interface circuit as recited in claim 11, which includes: a blocking diode connected between said voltage source and said second controlling device terminal; and a high-voltage resistor connected to said second controlling device terminal and a high-voltage source.
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) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |