US3979667A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical indicators
Assignee: DIPLEX Ltd
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Filing: 1974-12-13
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Granted: 1976-09-07
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Expires: 1994-12-13
Abstract
Abstract A domestic soil-moisture indicator of the kind including a probe comprising a pair of electrodes with spaced ends for insertion in the soil whereby the resistance of the conductive path established between them by the soil to be tested varies in resistance with the moisture of the soil. The improvement comprises a control circuit responsive to the value of the variable resistance and including a pair of light-emitting devices, connected in such a way that the total power between them is substantially constant and, at one end of the scale of value of the variable resistance, one device is fully on and the other is off, while at the other end of the scale the one device is off and the other is fully on, the brightness of the two devices varying between these extremes for intermediate values. The light-emitting devices are preferably light-emitting diodes each of which is connected in series with one of a complementary pair of emitter-following transistors connected to the division point of a potential divider consisting of the variable soil resistance and a fixed resistance connected in series with one another across the source of supply.
Inventors
- 👤 Nigel W. Cornes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:37
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/165; G01R19/16566; G01R19/16571; G01N; G01N33/00; G01N33/24; G01N33/246; G01R17/00; G01R17/10; G01R17/16; G01R27/00; G01R27/02; G01N27/00; G01N27/02; G01N27/04; G01N27/048
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
199 words
In a domestic soil-moisture indicator including a probe comprising a pair of insulated electrodes, said electrodes having spaced ends for insertion in soil whose moisture content is to be measured, whereby said soil constitutes a variable resistance between said electrodes, the improvement which comprises a control circuit including a source of electric power, a fixed resistor connected in series with said variable resistance to constitute a voltage divider across said source of supply, said voltage divider having a division point, a pair of light-emitting devices, a complementary pair of emitter-following transistors, said transistors each being connected in series with a respective light-emitting device in opposite senses across said source of supply and connections to said transistors from said division point of said voltage divider, whereby the total illumination emitted by said light-emitting devices is controlled to be substantially constant and, at one end of the scale of values of said variable resistance, one of said devices is fully on and the other said device is off, while at the other end of the scale said one device is off and said other device is fully on, the brightness of said two devices varying between these extremes for intermediate values.
Claim 2
Dependent Claim
199 words
In a domestic soil-moisture indicator including a probe comprising a pair of insulated electrodes, said electrodes having spaced ends for insertion in soil whose moisture content is to be measured, whereby said soil constitutes a variable resistance between said electrodes, the improvement which comprises a control circuit including a source of electric power, a fixed resistor connected in series with said variable resistance to constitute a voltage divider across said source of supply, said voltage divider having a division point, a pair of light-emitting devices, a complementary pair of emitter-following transistors, said transistors each being connected in series with a respective light-emitting device in opposite senses across said source of supply and connections to said transistors from said division point of said voltage divider, whereby the total illumination emitted by said light-emitting devices is controlled to be substantially constant and, at one end of the scale of values of said variable resistance, one of said devices is fully on and the other said device is off, while at the other end of the scale said one device is off and said other device is fully on, the brightness of said two devices varying between these extremes for intermediate values.
Claim 3
Dependent Claim
216 words
An electrical measuring device for indicating the value of a single parameter including a first resistance, said first resistance varying with the value of said parameter to provide a signal dependent on said value, a second resistance connected in series with said first resistance to constitute a voltage divider having a division point, a source of power connected to said resistances, said voltage divider being connected across said source, a plurality of light-emitting diodes and means for controlling the supply of power from said source to said diodes connected to said division point of said voltage divider, said means including a complementary pair of emitter-following transistors, said transistors each being connected in series with a respective light-emitting diode in opposite senses across said source, whereby the current in each said transistor is controlled in accordance with the potential of said division point of said voltage divider so that the total illumination emitted by said diodes is substantially constant and, at one end of the scales of values of said parameter, one of said diodes is fully on and the other diode is off, while at the other end of the scale said one diode is off and the other diode is fully on, the brightness of said two diodes varying between these extremes for intermediate values.
Claim 4
Dependent Claim
216 words
An electrical measuring device for indicating the value of a single parameter including a first resistance, said first resistance varying with the value of said parameter to provide a signal dependent on said value, a second resistance connected in series with said first resistance to constitute a voltage divider having a division point, a source of power connected to said resistances, said voltage divider being connected across said source, a plurality of light-emitting diodes and means for controlling the supply of power from said source to said diodes connected to said division point of said voltage divider, said means including a complementary pair of emitter-following transistors, said transistors each being connected in series with a respective light-emitting diode in opposite senses across said source, whereby the current in each said transistor is controlled in accordance with the potential of said division point of said voltage divider so that the total illumination emitted by said diodes is substantially constant and, at one end of the scales of values of said parameter, one of said diodes is fully on and the other diode is off, while at the other end of the scale said one diode is off and the other diode is fully on, the brightness of said two diodes varying between these extremes for intermediate values.
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) | 1979-09-07 | 1980-03-08 | 1980-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-07 | 1984-03-08 | 1984-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-07 | 1988-03-08 | 1988-09-07 | $7700.00 | Window Closed / Lapsed |