Negative resistance: Difference between revisions
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[Edit] From more recent tests, the trace above is more likely to be caused by capacitance - I'm not sure if the test signal used was a sawtooth or a sine (which would reduce this) but more testing is needed to be sure. | [Edit] From more recent tests, the trace above is more likely to be caused by capacitance - I'm not sure if the test signal used was a sawtooth or a sine (which would reduce this) but more testing is needed to be sure. | ||
[[File:Ale+cakes-galenapyritemix-steel1.png]][[File:Ale+cakes-galenapyritemix-steel3.png]] | |||
More convincing possible negative resistance from this natural [[Perikon diode]] of intergrown [[pyrite]] and [[galena]] from Ale & Cakes, extremely strange anyway - and needs more investigation. | |||
Latest revision as of 20:09, 9 October 2026
Negative resistance is when a device or material allows more current to flow as voltage across it is *decreased*, or vice versa, less current is passed with an *increase* in voltage. It's principle use to to create very high speed oscillators, in the microwave range.
Some natural semiconductors also seem to have this capability, Cornish arsenopyrite and wolframite seem to occasionally. In a curve plot it looks like a reverse loop, it's hard to capture as it's rare.
This is potentially some negative resistance on a sample of arsenopyrite from Wheal Fortune, Gwennap.
[Edit] From more recent tests, the trace above is more likely to be caused by capacitance - I'm not sure if the test signal used was a sawtooth or a sine (which would reduce this) but more testing is needed to be sure.
More convincing possible negative resistance from this natural Perikon diode of intergrown pyrite and galena from Ale & Cakes, extremely strange anyway - and needs more investigation.