Iain may find this useful at school.

I find the fact that you can make an "active" electronic device from
materials readily to hand is astounding.
"Performance not marvellous"? - sure.
But an eg audio or 12 Mhz oscillator from Al sheet and galvanised iron wire
is incredible - but apparently credible :-)

     Russell

_________________________

DIY 'tunnel diode" made from galvanised wire and aluminium sheet.  [!!!!]
Used to implement a negative resistance oscillator - trialled from audio to
12 MHz.

  http://www.sparkbangbuzz.com/els/ntype-nr-el.htm

Similar devices may be made using

iron pyrites - http://www.sparkbangbuzz.com/els/iposc-el.htm
&
zinc -  http://www.sparkbangbuzz.com/els/zincosc-el.htm   (heat modified
galvanised iron sheet)

Also carbon arc - which may rely on relaxation oscillation rather than
negative resistance. Or not.

           http://www.sparkbangbuzz.com/els/arcosc-el.htm

Corona oscillator and amplifier

           http://sparkbangbuzz.com/corona-osc/corona-osc.htm

While you're here:

DIY CRTs  - http://www.sparkbangbuzz.com/crt/crt6.htm

DIY Photocell  - http://www.sparkbangbuzz.com/els/photocell-el.htm

Poulsen Arc oscillator  -
https://pe2bz.philpem.me.uk/Comm/-%20ELF-VLF/-%20Info/-%20History/PoulsenAr=
cOscillator/poulsen1.htm



______________________________

BLACK HOLE

           http://www.sparkbangbuzz.com/index.html

P:\ATW+China_Backup_from_T\0902_China0902\052_090220_SG_India_Mercy_Arab_a2=
\PICT1153`10190219`_RP
Japanese Students outside mosque Little India 2009_q3.jpg




Making a more "traditional" tunnel diode may "not be too hard".
"Heavy doping" is a bonus for DIY applications


https://www.elprocus.com/tunnel-diode-circuit-with-operations-and-applicati=
ons/

______________________________________________

1/2 mW tunnel diode transmitter in (target) 1 mm^3 volume
           1/16000 th of a cubic inch -
           say 0.04 inch cubed
           ~=3D 1.25/32nd  on a side cube


https://www.semanticscholar.org/paper/Neuron-action-potential-detection-wit=
h-tunnel-diode-Chen-Tabib-Azar/698a52528849b5e4f99232f283189e0a815f7bfa

___________________________________________

1960
http://www.rfcafe.com/references/popular-electronics/tunnel-diode-september=
-1960-popular-electronics.htm
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