US5523665A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Active discharge circuit for charged capacitors
Assignee: Fluke Corp
•
Filing: 1994-10-26
•
Granted: 1996-06-04
•
Expires: 2014-10-26
Abstract
Abstract An active discharge circuit provides for the discharge of filter capacitors in a power supply in the absence of a.c. line power. A detector provides a signal responsive to the removal of the pulsating d.c. charging voltage from the capacitors and a switch responsive to the detector signal closes, coupling an energy dissipating element, in the form of a resistor or a transistor, across the filter capacitor to dissipate its stored energy.
Inventors
- 👤 David K. Deaver
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:27
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/02; H02H3/021; H02H3/023
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
101 words
An active discharge circuit for discharging a filter capacitor when a pulsating d.c. charging voltage is removed, comprising: (a) a detector for generating a signal responsive to the removal of said pulsating d.c. charging voltage, said detector comprising a diode, a resistor, and a capacitor wherein the time constant of the series combination of said resistor and said capacitor is substantially longer than the period of said pulsating d.c. charging voltage; (b) an energy dissipating element; and (c) a semiconductor switch disposed in series between said filter capacitor and said energy dissipating element wherein said switch closes responsive to said signal.
Claim 2
Dependent Claim
101 words
An active discharge circuit for discharging a filter capacitor when a pulsating d.c. charging voltage is removed, comprising: (a) a detector for generating a signal responsive to the removal of said pulsating d.c. charging voltage, said detector comprising a diode, a resistor, and a capacitor wherein the time constant of the series combination of said resistor and said capacitor is substantially longer than the period of said pulsating d.c. charging voltage; (b) an energy dissipating element; and (c) a semiconductor switch disposed in series between said filter capacitor and said energy dissipating element wherein said switch closes responsive to said signal.
Claim 3
Dependent Claim
16 words
An active discharge circuit according to claim 1 wherein said semiconductor switch comprises a bipolar transistor.
Claim 4
Dependent Claim
23 words
An active discharge circuit according to claim 2 wherein said transistor dissipates a substantial portion of the stored charge, from said filter capacitor.
Claim 5
Dependent Claim
25 words
An active discharge circuit according to claim 1 wherein said energy dissipating element dissipates a substantial portion of the stored charge from said filter capacitor.
Claim 6
Dependent Claim
132 words
In a power supply employing a filter capacitor to obtain a smoothed d.c. output voltage from a pulsating d.c. charging voltage, an active discharge circuit for discharging said filter capacitor when said pulsating d.c. charging voltage is removed, comprising: (a) a detector for generating a signal responsive to the removal of said pulsating d.c. charging voltage, said detector comprising a diode, a resistor, and a capacitor wherein the time constant of the series combination of said resistor and said capacitor is substantially longer than the period of said pulsating d.c. charging voltage; (b) an energy dissipating element; and (c) a transistor having a collector-emitter junction disposed in series between said filter capacitor and said energy dissipating element and a base coupled to said detector wherein said transistor conducts responsive to said signal.
Claim 7
Dependent Claim
132 words
In a power supply employing a filter capacitor to obtain a smoothed d.c. output voltage from a pulsating d.c. charging voltage, an active discharge circuit for discharging said filter capacitor when said pulsating d.c. charging voltage is removed, comprising: (a) a detector for generating a signal responsive to the removal of said pulsating d.c. charging voltage, said detector comprising a diode, a resistor, and a capacitor wherein the time constant of the series combination of said resistor and said capacitor is substantially longer than the period of said pulsating d.c. charging voltage; (b) an energy dissipating element; and (c) a transistor having a collector-emitter junction disposed in series between said filter capacitor and said energy dissipating element and a base coupled to said detector wherein said transistor conducts responsive to said signal.
Claim 8
Dependent Claim
25 words
An active discharge circuit according to claim 5 wherein said energy dissipating element dissipates a substantial portion of the stored charge from said filter capacitor.
Claim 9
Dependent Claim
23 words
An active discharge circuit according to claim 5 wherein said transistor dissipates a substantial portion of the stored charge from said filter capacitor.
References Cited (Backward Citations)
US4536693A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-06-04 | 1999-12-04 | 2000-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-06-04 | 2003-12-04 | 2004-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-06-04 | 2007-12-04 | 2008-06-04 | $7700.00 | Window Closed / Lapsed |