Solid-state anemometer

A number of years ago (probably at least seven), one of the American pro electronics magazines published a reader's circuit for a zero-moving parts anemometer.
From memory, it used three transistors on the apexes of an equilateral triangle, with a fourth reference device in the centre.

Does anyone have a link to this or a similar article, please?

it used three transistors on the apexes of an equilateral triangle,

I think those would be ultrasonic transducers. By measuring the flight time (in both directions) you can calculate the wind vector. There was a thread about this here a few weeks ago but I don't know if it ever amounted to anything.

No, they were not ultrasonic - it had zero moving parts.
Could have been temperature sensors (something like a TO92 can), but I thought they were fairly ordinary transistors.
I'm guessing it was like a hot wire anemometer.

I really wish I'd photocopied the article. :frowning:

I remember a similar article from years ago (the 50s maybe) reposted to some web site, about a couple of kids who used vacuum tube circuits to build an anemometer. Had something to to with temperature measurements and cooling effects of the wind.

As best I recall it wasn't terribly accurate, but pretty neat all the same.


Hot wire anemometers were good enough for the early NASA Mars probes, IIRC.
[googles] Still are, it seems.

The article I saw would have been late 90's / early 00's, and indicated direction (I think) as well as speed.
I forget, but I guess this implies some form of physical shielding of the sensors.

Not to be pedantic, but I googled for "solid state anemometer" and found this:
It looks like it might fit the bill...

Yes, I googled that one too, but it isn't quite what I remembered.
It's a pity there's no circuit.
I thought the one I saw sensed direction as well as speed, and as I said, I distinctly remember the arrangement of the sensors.
I also had a thought that it was in a pro magazine; my impression is Electronics Now is not a magazine I would have had access to at the time.
Just remembered it may have been the one Bob Pease has a column in - off to trawl through "Electronic Design" archives.
Thanks all.

Got it via the author's name from Electronics Design, but this one was published in EDN.


Here's something that builds on the idea, and has a readable schematic:, and there's another version by the same author here:

I'm not able to find that Cyntec se102 thermistor...

It seems from that EDN article that the physical arrangement of the three transistors is critical to the operation of the sensor. Shame that there's no diagram, or even dimensions of the most important part of the design.

I'm sure the original printed article had better detail in that respect.
I'm going to try contacting the author directly.

Found another link while searching for "thermal anemometer": Thermal anemometer

This might be the mother lode: the Micro Gust Thermal Anemometer.

It would appear that the LM399 diode is obsolete, and I don't see a replacement. :frowning:

this article is incomplete. but I found a complete one

Yes, Woodward is the author alright (see reply #7), but although I contacted the college, I never got a reply.
Maybe he's retired.