Monostable switching circuit
AssigneeRCA Corporation
InventorAdel Abdel Aziz Ahmed
Life of this patent
Estimating the term…
Abstract
An input signal activates a current source for charging a capacitor. A first switch is closed and a memory element is subsequently SET as the capacitor voltage increases. When SET, the memory element closes a second switch and reverses the charging current whereupon the first switch is subsequently opened. The memory element is RESET upon termination of the input signal whereupon the cycle may be repeated. The switches may be connected in series for providing an output indication during the period both are closed.
Claims16
A circuit, for producing a momentary output signal manifestation in response to a change in an input signal from a first level to a second level;
- said circuit comprising:
- current source means having first and second input terminals for receiving said input signal thereacross, an output terminal responsive to said input signal when it is at said second level for producing an output current, and first and second control terminals for controlling the sense of said output current in accordance with the magnitude of a control current conducted between said control terminals, said control current having first and second magnitudes;
- normally open switch means connected between said first and second control terminals for conducting said control current therebetween when closed and for blocking the flow of said control current when open, said switch means including a trigger terminal responsive to a trigger signal supplied thereto for closing said switch and means for maintaining said switch closed once triggered;
- and
- means for applying a trigger signal to said trigger terminal of said normally open switch means, said means including a circuit reference potential point, a capacitor connected between said reference potential point and said output terminal of said current source and a threshold conduction device connected between said output terminal and said trigger terminal.
In combination:
- first and second terminals for receiving an input signal thereacross;
- a node for connection to an energy storage element;
- a first current source connected between said first terminal and said node for conducting a first current therebetween in one sense when said input signal is present, said first current source having an inhibit terminal for receiving an inhibit signal;
- a second current source connected between said second terminal and said node for conducting a second current therebetween of opposite sense when said input signal is present, said second current source having an enable terminal for receiving an enable signal;
- bistable switch means having a normally non-conductive path connected between said inhibit and enable terminals and having also a trigger electrode responsive to a trigger signal for placing said path of said bistable switch means in a latched conductive state;
- and
- means for applying said trigger signal to said trigger electrode comprising a threshold conduction device connected between said trigger electrode and said node.
In combination;
- a capacitor;
- a first current source connected across said capacitor for supplying a charging current thereto in response to an input signal;
- a second current source;
- first means responsive to the voltage across said capacitor when it reaches a given level for connecting the second current source across said capacitor in a sense to discharge the same and for disabling said first current source;
- and
- second means coupled to said capacitor responsive to the voltage thereacross after it reaches said given level for producing an output signal indication of a duration dependent on the time required for said voltage to reduce to a second, lower level.
Dependencies are inferred from the claim text.