US3885501A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fail-safe electrical timer
Assignee: Calspan Corp
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Filing: 1973-11-16
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Granted: 1975-05-27
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Expires: 1993-11-16
Abstract
Abstract A device to deactivate an electrical circuit after a preset period of time. Deactivation is accomplished by the depletion of the power supply battery through a preset load which is an oscillator that is connected through an AC link into the circuit to be deactivated.
Inventors
- 👤 Jr Clayton J Schneider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:27
CPC Classifications
F; F42; F42C; F42C11/00; F42C11/001; F42C11/007; F42C11/06
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
92 words
A fail-safe electrical timer which will become deactivated after a preselected time and upon the intervening failure of a component including: power means; oscillator means driven by said power means and producing an AC output; rectifier means for rectifying said AC output; firing capacitor means charged by said rectifier means; thyristor firing circuit means including a normally open firing switch and a detonator connected to said firing capacitor means whereby upon the closing of said firing switch the said firing capacitor means is allowed to discharge through and thereby activate said detonator.
Claim 2
Dependent Claim
92 words
A fail-safe electrical timer which will become deactivated after a preselected time and upon the intervening failure of a component including: power means; oscillator means driven by said power means and producing an AC output; rectifier means for rectifying said AC output; firing capacitor means charged by said rectifier means; thyristor firing circuit means including a normally open firing switch and a detonator connected to said firing capacitor means whereby upon the closing of said firing switch the said firing capacitor means is allowed to discharge through and thereby activate said detonator.
Claim 3
Dependent Claim
25 words
The fail-safe electrical timer of claim 1 further including an AC link means for providing a connection between said oscillator means and said rectifier means.
Claim 4
Dependent Claim
25 words
The fail-safe electrical timer of claim 1 wherein said oscillator means includes a variable, charging resistor for controlling the depletion time for the power means.
Claim 5
Dependent Claim
34 words
The fail-safe electrical timer of claim 1 wherein said thyristor firing circuit means further includes a thyristor and a resistor for stabilizing said thyristor in a nonconducting condition when said firing switch is open.
Claim 6
Dependent Claim
23 words
The fail-safe electrical timer of claim 1 wherein said power means is a battery and said detonator is connected to a land mine.
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) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |