Patent US3762331A successfully refreshed from Google Patents.
US3762331A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Firing circuit for blasting caps
Assignee: The Association of Motion Picture and Television Producers Inc
•
Filing: 1972-03-29
•
Granted: 1973-10-02
•
Expires: 1992-03-29
Abstract
Abstract The present system for selectively firing explosive charges utilizes as firing a signal an alternating current having a frequency of the order of 10 kHz and a voltage of at least 60 volts, which is transmitted by cable to the explosive site. A discriminating circuit adjacent each firing squib includes a step-down transformer with saturable core which effectively blocks spurious 60 cycle alternating current voltages. Series and shunt capacitances further insure against spurious signals and tune the circuit to enhance response to the firing signal. Convenient testing and monitoring circuits are described.
Inventors
- 👤 P Vlahos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:34
CPC Classifications
F; F42; F42D; F42D1/00; F42D1/04; F42D1/045; F42D1/05
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
50 words
A firing circuit according to claim 1, and wherein said primary and secondary transformer windings are electromagnetically coupled By ferromagnetic core means of such characteristics as to be fully saturated in response to application to the primary winding of a 60 Hz alternating voltage of the order of one volt.
Claim 2
Dependent Claim
33 words
A firing circuit according to claim 1, and including a resistive shunt connected across said conductive circuit means at the firing station, and means for locally grounding the midpoint of the resistive shunt.
Claim 3
Dependent Claim
29 words
A firing circuit according to claim 1, and including reactance means connected in series with said conductive circuit means adjacent the firing station for attenuating spurious radio frequency signals.
Claim 4
Dependent Claim
36 words
A firing circuit according to claim 1, and in which said signal generating circuit means have such characteristics that said firing signal has a voltage of approximately 130 volts and a frequency of approximately 8,500 Hz.
Claim 5
Dependent Claim
42 words
A firing circuit according to claim 1, and in which said secondary winding is directly connected to the igniter and forms a shunt circuit in parallel with the igniter having a resistance less than about one tenth the resistance of the igniter.
Claim 6
Dependent Claim
57 words
A firing circuit according to claim 2, and in which said secondary winding is directly connected to the igniter and forms a shunt circuit in parallel with the igniter, the shunt impedance to A.C. voltages that are of power frequency and that exceed about 1/10 volt being less than about one tenth the impedance of the igniter.
Claim 7
Dependent Claim
145 words
A firing circuit for igniting an explosive charge at a firing station, comprising circuit means at a control station remote from the firing station for selectively generating an alternating current firing signal having a signal voltage between about 60 and about 240 volts and a signal frequency of the order of 10 kHz, conductive circuit means for selectively transmitting the firing signal from the control station to the firing station, an electrical igniter at the firing station in firing relation to the explosive charge and responsive to a firing voltage of the order of 1/100 of said signal voltage, a step-down transformer adjacent the firing station having a primary winding coupled to said conductive circuit means and a secondary winding coupled to the igniter, and a capacitance conneced in shunt to the transformer primary winding and forming therewith a circuit resonant at said signal frequency.
Claim 8
Dependent Claim
31 words
A firing circuit according to claim 8, and including a second capacitance, said transformer primary winding being coupled to said conductive circuit means via a series connection of said second capacitance.
References Cited (Backward Citations)
US3670653A
Cited
US3682098A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-01 | 1977-04-02 | 1977-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-01 | 1981-04-02 | 1981-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-01 | 1985-04-02 | 1985-10-02 | $7700.00 | Window Closed / Lapsed |