DC-DC converter for low voltage power source

1. A power conversion unit for a low voltage thermoelectric generator comprising:

a self-oscillating two-terminal device configured to convert a DC voltage from said low voltage thermoelectric generator of less than 0.7 V into a self-oscillating alternating current AC signal;

a transformer connected to the self-oscillating device and configured to transform the self-oscillating AC signal into a transformed AC signal; and

an AC-to-DC converter configured to convert the transformed AC signal into a DC signal,

wherein said self-oscillating two-terminal device includes, for terminals, only an input terminal connected to the low voltage thermoelectric generator and an output terminal connected to the transformer.

2. The unit of claim 1 , wherein the self-oscillating device comprises a Reed switch.

3. The unit of claim 2 , wherein the Reed switch comprises:

a coil connected in series with a source of the DC voltage; and

a magnetic cantilever switch connected in series with the source of the DC voltage and configured to periodically open when current flow through the coil reaches a predetermined level.

4. The unit of claim 3 , wherein the magnetic cantilever switch is configured to open when current flow through the coil reaches an upper set point.

5. The unit of claim 3 , wherein the magnetic cantilever switch is configured to close when current flow through the coil reaches a lower set point.

6. The unit of claim 3 , wherein the magnetic cantilever switch is configured to close when current flow through the coil reaches an upper set point.

7. The unit of claim 3 , wherein the magnetic cantilever switch is configured to open when current flow through the coil reaches a lower set point.

8. The unit of claim 2 , wherein the Reed switch comprises a micromechanical switch.

9. The unit of claim 1 , wherein the self-oscillating device comprises a tunnel diode connected in series between a source of the DC voltage and the transformer.

10. The unit of claim 9 , wherein the tunnel diode is configured to operate for input voltages in a negative differential resistance regime where an increase in voltage results in a decrease in current flow.

11. The unit of claim 10 , wherein the tunnel diode is configured to operate in a range between 65 mV and 500 mV.

12. The unit of claim 9 , further comprising:

at least one more tunnel diode connected in parallel with said tunnel diode connected in series between the source of the DC voltage and the transformer.

13. The unit of claim 1 , wherein the AC-DC converter comprises a rectifying circuit.

14. The unit of claim 1 , further comprising:

a subsequent DC-DC converter configured to convert the DC signal into a stepped up DC voltage signal.

15. A thermoelectric power supply system comprising:

a low voltage thermoelectric generator;

a self-oscillating two-terminal device configured to convert a DC voltage source from the low voltage thermoelectric generator of less than 0.7 V into a self-oscillating alternating current AC signal;

a transformer connected to the self-oscillating device and configured to transform the self-oscillating AC signal into a transformed AC signal; and

an AC-to-DC converter configured to convert the transformed AC signal into a DC signal,

wherein said self-oscillating two-terminal device includes, for terminals, only an input terminal connected to the low voltage thermoelectric generator and an output terminal connected to the transformer.

16. The unit of claim 15 , wherein the low voltage thermoelectric generator comprises at least one of a thermoelectric device, and a Seebeck device.