Tunnel Diodes - They look awesome

ebp

Joined Feb 8, 2018
2,332
They may still be in production in Russia (I've seen them for sale from ebay vendors in Ukraine, but I haven't look for a few years), but otherwise they are no longer being made. They were also useful for producing very fast pulses in test instruments such as time domain reflectometers.
 

nsaspook

Joined Aug 27, 2009
7,296
Hi all,

Been a while since I lasted posted here! Just writing up an article about Active and passive components and came across the tunnel diode. I am amazed at how an oscillator can be made using one thanks to its negative resistance over a specific operational range :O



https://www.elprocus.com/tunnel-diode-circuit-with-operations-and-applications/

All the best,
Robin
You can see the same negative resistance effect with a



https://en.wikipedia.org/wiki/Pearson–Anson_effect
 

MrChips

Joined Oct 2, 2009
21,123
Tunnel diodes are used in nuclear instrumentation electronics as fast analog comparator circuits.
They are also found in Tektronix 422 oscilloscopes.
 

AlbertHall

Joined Jun 4, 2014
9,873
They may still be in production in Russia (I've seen them for sale from ebay vendors in Ukraine, but I haven't look for a few years), but otherwise they are no longer being made. They were also useful for producing very fast pulses in test instruments such as time domain reflectometers.
Also were used in the trigger pulse generator in oscilloscopes.
 

ebp

Joined Feb 8, 2018
2,332
There is one manufacturer in the US: ...
I get the impression that SSDI will make you a batch to order. I can't imagine them being cheap.
It looks like there are lots of eBay vendors still selling TDs from the USSR.

Tunnel diodes were making the rounds among hobbyists in the 1970s as I recall. I think there might even have been one in the Motorola HEP series.
 

rsjsouza

Joined Apr 21, 2014
248
I get the impression that SSDI will make you a batch to order. I can't imagine them being cheap.
It looks like there are lots of eBay vendors still selling TDs from the USSR.

Tunnel diodes were making the rounds among hobbyists in the 1970s as I recall. I think there might even have been one in the Motorola HEP series.
Yes, that seems to be the case as I couldn't find any distributor that sells these.
 

RichardO

Joined May 4, 2013
2,271
For what it is worth...
Years ago I wanted a fast pulse to test the bandwidth of my used o'scope -- a Tektronix 475A. I was disappointed with the speed of a tunnel diode. I had much better results using a 2N2369 as an avalanche transistor.
 

AlbertHall

Joined Jun 4, 2014
9,873
For what it is worth...
Years ago I wanted a fast pulse to test the bandwidth of my used o'scope -- a Tektronix 475A. I was disappointed with the speed of a tunnel diode. I had much better results using a 2N2369 as an avalanche transistor.
I used to work on TDRs and they used an avalanche transistor circuit which, if memory serves, was also based on the '2369.
 

RichardO

Joined May 4, 2013
2,271
I used to work on TDRs and they used an avalanche transistor circuit which, if memory serves, was also based on the '2369.
An the famous Jim Williams used the 2N2369 in his avalanche circuit to test op-amp slew rates.

It was pure luck that I chose the 2n2369 for my avalanche circuit. It was years later that I saw the Jim Williams app note. As I say it: If I have a choice between good and lucky, I will settle for lucky".
 

OBW0549

Joined Mar 2, 2015
3,406
een a while since I lasted posted here! Just writing up an article about Active and passive components and came across the tunnel diode. I am amazed at how an oscillator can be made using one thanks to its negative resistance over a specific operational range
Ahhh... tunnel diodes. These are ancient, not new: my GE Transistor Manual, 7th Edition (1964) has about 25 pages of tunnel diode circuits.

Good stuff-- for nostalgia, anyway.
 

Bordodynov

Joined May 20, 2015
2,603
An the famous Jim Williams used the 2N2369 in his avalanche circuit to test op-amp slew rates.

It was pure luck that I chose the 2n2369 for my avalanche circuit. It was years later that I saw the Jim Williams app note. As I say it: If I have a choice between good and lucky, I will settle for lucky".
By the way, in my collection there is a model for this transistor working in an avalanche mode and if you take information on my link, then in the folder Example There are several tests of the operation of transistors in the mode of relaxation oscillations in direct (avalanche) and reverse mode. There are also circuits designed to test oscilloscopes.
 
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