Tunnel diode "Interesting" (i.e. useless) experiments

Post new topic   Reply to topic

View previous topic View next topic Go down

Re: Tunnel diode "Interesting" (i.e. useless) experiments

Post by Admin on Wed Mar 08, 2017 5:07 pm

Hi Glenn,
Thank you for the info. It is always nice to read about perriferal information regarding these things.

BTW, I have found another use for the resistive divider/tunnel diode, I measured the length of 1/2 a drum of RF cable. The TD got the cable to resonate and I just measured the frequency - 1.7MHz. Velocity factor known to be about 0.8, so I had 35 metres on the drum.

BR Harry

_________________
(I will listen to 14.190MHz USB every Sunday afternoon 15:00 to 18:00 to mid July)
avatar
Admin
Admin

Posts : 387
Join date : 2012-11-24
Age : 65
Location : Märsta, Sweden

View user profile http://www.sm0vpo.com

Back to top Go down

Re: Tunnel diode "Interesting" (i.e. useless) experiments

Post by Glenndk on Mon Mar 06, 2017 4:08 pm

Admin wrote:Hello Glenn,
...
I shall have to study the links a bit more, especially the OpAmp circuits. How the h#11 did you manage to find that idea? As I always say, the people on this forum seem to know everything :-) If they don't know it then they find it.

BR Harry

The op-amp can be exchanged for the lambda diode; it just need the resonance circuit to go into chaotic oscillation. You make the transfer function non-linear with the diodes and resistors:
http://www.vk6fh.com/vk6fh/lambda_diode.htm

-

Synchronization of chaos:
https://en.wikipedia.org/wiki/Synchronization_of_chaos
Quote: "...
having two chaotic systems evolving in synchrony might appear surprising. However, synchronization of coupled or driven chaotic oscillators is a phenomenon well established experimentally and reasonably well understood theoretically.
..."


Glenndk

Posts : 17
Join date : 2017-01-06
Location : Copenhagen, Denmark

View user profile

Back to top Go down

Re: Tunnel diode "Interesting" (i.e. useless) experiments

Post by Admin on Mon Mar 06, 2017 11:54 am

Hello Glenn,
Now THAT is novel. A chaos generator :-)

I would be interested to see the applications for such a device. I can see a random-number generator application. One cannot help but wonder just what Chua was trying to achieve (like the first person to milk a cow :-)

I shall have to study the links a bit more, especially the OpAmp circuits. How the h#11 did you manage to find that idea? As I always say, the people on this forum seem to know everything :-) If they don't know it then they find it.

BR Harry

_________________
(I will listen to 14.190MHz USB every Sunday afternoon 15:00 to 18:00 to mid July)
avatar
Admin
Admin

Posts : 387
Join date : 2012-11-24
Age : 65
Location : Märsta, Sweden

View user profile http://www.sm0vpo.com

Back to top Go down

"Interesting" NDR experiments

Post by Glenndk on Sun Mar 05, 2017 8:42 pm

How about a chaos oscillator - sinusoidal oscillators are boring and too predictable Smile :
https://commons.wikimedia.org/wiki/File:Chua%27s_circuit_with_Chua_diode.svg
Quote: "...
English: Schematic diagram of Chua's circuit, a simple electronic circuit which exhibits chaotic behavior. Invented by Leon Chua in 1983, it and is very widely used as a standard example of chaotic oscillation. It consists of one inductor (L), two capacitors (C1 and C2), one resistor (R), and a nonlinear negative resistance (NR), called Chua's diode. This device is not a single electronic component but a nonlinear active circuit built using op amps.
..."

https://en.wikipedia.org/wiki/Chua%27s_diode

http://www.cmp.caltech.edu/~mcc/chaos_new/Chua.html
https://en.wikipedia.org/wiki/Chua%27s_circuit

https://en.wikipedia.org/wiki/Chaotic_cryptology

Lissajou curves - go home Smile :
https://en.wikipedia.org/wiki/Lissajous_curve

How about a sinusoidal oscillator modulated by a chaos generator - how does it sound? Or Lissajou curves (two sinusoidal oscillator) modulated by low frequency chaos each.

Glenndk

Posts : 17
Join date : 2017-01-06
Location : Copenhagen, Denmark

View user profile

Back to top Go down

Tunnel diode "Interesting" (i.e. useless) experiments

Post by Admin on Wed Mar 01, 2017 11:18 pm

Hi Ivan and others,
I have difficulty sleeping at the moment, so I did a couple of silly experiments with my Russian Tunnel diode. Perhaps not much serious use, but they could give a bit of food for thought and open up innovative ideas for new projects:

1 - I cut a bit of scrap RG58 coaxial cable to 1/2-wavelength at 145MHz (x VF). Shorted each end with a 1.5cm Dia. loop of wire. I then connected the Tunnel Diode to one loop, and it oscillated very strongly. Cut off the loop at the other end and the frequency shot down to 72.5 MHz. As I clipped off bits of wire I could "prune" the oscillator to any frequency I want. The frequency is surprisingly stable, even when the wire was coilled up.

2 - I have to get rid of stuff that I have no further space for. One of them is a homebrew 145MHz, 4-element Yagi (it had 8 elements but I cannot put it together in this little apartment). It goes in the bin this weekend. Tonight I connected the Tunnel diode inside the coax connector block: the feed point of the Yagi. That, too, began to oscillate immediately, and it was quite strong. Touching the elements, or putting my hand close to them, did move the frequency slightly.

I know that anything with resonance can be made oscillate, and this could open up all manner of project ideas. How about a resonant cavity built into a galvanised dust-bin? Or metal air ducts? I once used a galvanised dustbin as an antenna filter for 28MHz, when a neighbour was running his 27 Mhz CB set "with boots on" (linear amplifier). How about a VFO made with a bit of copper pipe, center resonator rod, and a mechanical piston to control the frequency? Could easily get a frequency range of 10:1 or more Very Happy 

Ok, I am going to try to get some sleep now, but thought I would just put something into writing to share ideas, and also serve as a reminder for this 65-year old brain.

Good night and very best regards to all reading this. Harry - SM0VPO

_________________
(I will listen to 14.190MHz USB every Sunday afternoon 15:00 to 18:00 to mid July)
avatar
Admin
Admin

Posts : 387
Join date : 2012-11-24
Age : 65
Location : Märsta, Sweden

View user profile http://www.sm0vpo.com

Back to top Go down

Re: Tunnel diode "Interesting" (i.e. useless) experiments

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

Post new topic   Reply to topic
 
Permissions in this forum:
You can reply to topics in this forum