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Multiple LED oscillations / pulsations using (tenuous) "Cat's Wisker" switches
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RJSV:
Post#2,  please see also Nov. 5 1:58pm post.   In detail, an experimental rig passes a +3V DC supply battery through a shared 1K ohm resistor to four connected LEDs.  For switching, each Led is connected to ground (minus),  by use of a wire strand "Cat's Whisker".  A stranded ground wire is mounted nearby,  with desired effect of having 'flakey', random contacts to light up each of the LEDs,  by way of movement, and possibly also by contact degradation (copper surface oxidizing due to current flow).   One visual effect is a so-called 'glory stealing' of a blue LED illumination, when a RED LED is then put into the parallel mix. 
     Now, a RED LED at 1.8 Volts will suppress an illuminated BLUE LED (at 2.5 volts), by keeping the voltage down.  (Remember they interact, as they share the 1 Kohm supply resistor).  This causes a complementary "one or the other" visual effect where the light appears to move or 'flicker' back and forth, as the RED LED contact acts to switch the lower voltage RED LED in and out of the parallel circuit.  That effect is clearly due to the higher illuminating 'ON' voltage requirement of the BLUE LED.
     Extending this effect to using a 'flakey' switching contact, via the tiny Cat's Whiskers, the visual effect becomes analog,  that is the on and off 'flickers' become subtle 'pulsations'.  The 'BAD' contacts appear to introduce about 1 K ohms in some cases.  This all makes sense... However,  there are other similar visual effects, when the experimental rig is using only RED LEDs!
     With an experiment using just two RED LEDs,  each with a Cat's Whisker to minus supply,  there is observed similar visual 'surges' between them.  For example,  LED #1 will be pulsating bright and random for perhaps 30 seconds,  and meanwhile LED #2 will be dimly pulsating in opposition (one LED getting brighter while the other diminishes).  Also sometimes the 'dominant' LED will come on full for several seconds or more,  leaving the other LED dark.  Then,  often after perhaps 40 seconds,  the whole situation reverses and LED #2 takes on the dominant role.   I have a tentative, incomplete explanation:  With surface contact 'burning' or copper oxidizing the dominant LED eventually cannot sustain illumination.  Or, maybe the LED simply is heating up slightly.  At any case the dominant LED will stop conducting,  allowing the other LED to then take on the role (of flickering / surging in brightness).
     I am stymied by the behavior of this,  as the mechanical contacts would have to coordinate for this 'one or the other' trading of the LED dominance.  That's a stretch to believe.  Wondering also,  perhaps there are so-called "NEGATIVE RESISTANCE" effects on the diode V/I curves,
as seen in the micro-wave PIN diodes used in radio transmission.   Any help or even whacky theories out there?  Sorry no schematic.  Thanks
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