What is claimed is:
1. A high-voltage oscillator comprising:
a first normally-on switch in series with a resonant circuit;
a second normally-on switch in parallel with the resonant circuit; and
a control circuit preventing the simultaneous conduction of the two switches.
2. The oscillator of claim 1, comprising a single resonant circuit.
3. The oscillator of claim 1, wherein the control circuit has no auxiliary supply circuit.
4. The oscillator of claim 1, wherein said first switch is on during periods of recharge of a capacitor of the series resonant circuit, and is off during a resonance phase.
5. The oscillator of claim 1, wherein the control of the first switch is performed by comparing the voltage across the resonant circuit with a predetermined threshold.
6. The oscillator of claim 1, wherein the control of the second switch is performed by delaying a turn-on time of this switch with respect to an end of the conduction of the first switch.
7. The oscillator of claim 1, wherein said switches are bidirectional in current and voltage.
8. The oscillator of claim 1, wherein said switches are one-way switches.
9. The oscillator of claim 8, comprising a free wheel diode, reverse biased with respect to the second switch.
10. The oscillator of claim 9, wherein the resonance phase includes a first cycle of discharge of said capacitor through the second switch and a second cycle of discharge of said capacitor through said free wheel diode.
11. The oscillator of claim 8, wherein the second switch is formed of a thyristor having its anode connected on the side of the first switch.
12. The oscillator of claim 8, wherein the first switch is formed of an NPN-type bipolar transistor made normally on by the connection of its base and of its collector by means of a resistor, the emitter of the bipolar transistor being connected to the resonant circuit.
13. A D.C. supply circuit including the high-voltage oscillator of claim 1.
14. The D.C. supply circuit of claim 13, wherein an output capacitor is connected, in parallel with two rectifying diodes in series, to the second capacitor.
15. The supply circuit of claim 14, wherein a first rectifying diode connects one end of the resonant circuit to an electrode of the second switch and to a positive electrode of the output capacitor, the anode of the first rectifying diode being connected to the resonant circuit and to the cathode of a second rectifying diode connected to the free wheel diode.
16. The supply circuit of claim 14, wherein the biasing of the output voltage is chosen according to the electrode of the output capacitor to which is connected the reference of the supply voltage.
17. The supply circuit of claim 13, including a control circuit having the function of delaying the time of starting of the second switch according to the output voltage.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A modulated well telemetry apparatus comprising:
an electrically conductive pipe extending from above ground surface to a point below said surface inside a casing;
an electrical conductor located at a position a distance from said first electrically conductive pipe and extending from above said ground surface to a point below said surface;
modulated reflector sensor apparatus located below said surface for reflecting data on said well;
a RF transceiver located at said surface connected between said electrically conductive pipe and said electrical conductor, for transmitting a RF signal that is confined between said electrically conductive pipe and said electrical conductor to said modulated reflector sensor apparatus, and for receiving a signal modulated with well data and reflected by said modulated reflector apparatus.
2. The apparatus as described in claim 1, wherein said electrical conductor is small diameter pipe in a hole dug by water well drilling apparatus.
3. The apparatus as described in claim 1, wherein said electrical conductor is small diameter pipe in a preexisting hole located near said first electrically conductive pipe.
4. The apparatus as described in claim 1, wherein said electrical conductor is an existing nearby electrically conductive pipe.
5. The apparatus as described in claim 1, wherein said electrically conductive pipe defines a first portion and a second portion, said first and second portions being separated by an insulated portion, and said modulated reflector and sensor apparatus is connected across said insulated portion, and further comprises switching means for providing a connection between said first and second portions of said first electrically conductive pipe, and disconnecting said connection in accordance with sensor input to provide increased modulation of the signal reflected from said modulated reflector and sensor apparatus.
6. A modulated well telemetry apparatus comprising:
an electrically conductive pipe extending from above ground surface to a point below said surface inside an electrically conductive casing;
an electrical conductor located at a position a distance from said electrically conductive pipe and extending from above said ground surface to a point below said surface;
modulated reflector sensor apparatus located below said surface for reflecting data on said well;
a RF transceiver located at said surface connected between said electrically conductive pipe and said electrically conductive casing, and said electrical conductor, for transmitting a RF signal that is confined between said electrically conductive pipe and said electrically conductive casing, and said electrical conductor, and to said modulated reflector sensor apparatus, and for receiving a signal modulated with well data and reflected by said modulated reflector apparatus.
7. The apparatus as described in claim 6, wherein said electrical conductor is small diameter pipe in a hole dug by water well drilling apparatus.
8. The apparatus as described in claim 6, wherein said electrical conductor is small diameter pipe in a preexisting hole located near said electrically conductive pipe.
9. The apparatus as described in claim 6, wherein said electrical conductor is an existing nearby electrically conductive pipe.
10. The apparatus as described in claim 6, wherein said electrically conductive casing defines a first portion and a second portion, said first and second portions being separated by an insulated portion, and said modulated reflector, and sensor apparatus is connected across said insulated portion of said electrically conductive casing, and further comprises switching means for providing a connection across said insulated portion and disconnecting said connection in accordance with sensor input to provide increased modulation of the signal reflected from said modulated reflector and sensor apparatus.