[miguel]

Found this open-source diy air data instrument.

http://www.obairlann.net/reaper/arduino/airdata/

Seeing that it includes an air temp sensor, it would be easy to add a thermal snooper component to it. Does the snooper have a set constant temp that it refers to or does the constant change with time?

[Rick Masters]

Does the snooper have a set constant temp... constant change with time?

The classic snooper is a rate of temperature change indicator, or a thermal variometer. I was not involved in its design, but I assume the circuit makes a measurement, stores it, makes another a few miliseconds later and compares it to the first measurement. If the result is positive, it beeps; negative, it boops. The trick to making the thermal snooper useful is designing in the proper sensitivity.

The trick for the pilot is figuring out how to use this data.

See "Explorations with the Thermal Snooper" by Rick Masters
Soaring, August 1987
http://www.cometclones.com/illusion.htm

[miguel]

Thanks for the reply.

Back when the TS was popular, an occasional pilot would show up with one. They would stand on launch in a cacophony of bloops, bleeps, and bops for an inordinate amount of time. When the cacophony hit the crescendo they were looking for, they would launch and get a sled ride. I never thought much of them until I read your web site. I then tried to find one. Got close, but never could get one.

You had some old school schematics up for a while. I neglected to copy them down.

I contacted the fellow with the DIY air data gizmo. He gave me a run through and has made the code available on a web site. I have to figure out how to convert the data voltages to meaningful audio signals before I start acquiring parts

[Birren]

When did the Snooper first come out... 1990? I got one of the first ones (#13) and flew with it until selling it 2 years ago.

At first, I hated it. The fast and slow beeping and booping drove me nuts. Trouble was, I didn't know how to use what it was telling me. Took me 3 years to finally understand it, and it made a whole lot of difference when I did! It allowed me to know better the shape of a thermal and know where the stronger spots were without the lag time of a vario.

I put a small piece of duct tape over half the piezo speaker opening to dampen the sound a bit, just enough so I could still hear it above the wind, vario and radio chatter. It helped provide another piece to the puzzle.

Worked with a South African pilot -- Werner Terriblanche -- who was trying to make his own. The model he sent me for testing was visual-only with red and green lights. I worked with it for half a season but finally had to put it away because there is SO much visual in flying that trying to differentiate the lights (hell, just noticing them) was nearly impossible. Totally lost touch with Werner so I don't know what ever happened to his design.

- Peter

[Bob Kuczewski]

This sounds like it would be an interesting project. In the late 90s I began working with the Microchip PIC processor which was small, cheap, and had a built-in analog to digital converter. I built my own programmer for it, and I used it on several projects. It came with a free development kit available on line.

I'll bet there are much more sophisticated versions available a decade later. What processor are you thinking of using?

[Rick Masters]

People like to think that there is always a way to improve an instrument. This is not true. Oftentimes, an instrument is sufficient to provide EXACTLY the information you need to accomplish your task. This is true of the volt meter, the amp meter, the altimeter and the variometer. It is also true of the 1980s Thermal Snooper, or temperature variometer.

A faster response would degrade the instrument. A slower response would degrade the instrument. However, a more capable pilot will make the instrument more useful. That is what is needed.
See http://www.cometclones.com/illusion.htm

[miguel]

I am not trying to improve upon the instrument. I want one and there are none available. Programming is easier for me to manipulate than trying to synthesize the original circuit. It is a learning experience for me. If I get it to work, I will put the code up for anyone. If it doesn't work, it will become the brains in a swamp cooler project.

[Bill Cummings]

I have a Thermal Snooper, Ser. No. 00111, model 78-221-1.84
Al has been pestering me to buy it but after reading Rick's post about how he used it has renewed my interest. If on the other hand I still can't blend it into my over abundance of flight gizmo's what would be a fair price to sell it to Al?
Fair for both of us?
I don't even remember what I paid for it but I remember anguishing about separating myself from the money at the time. (I'm pretty tight so maybe it wasn't really all that expensive.)

[Birren]

The original snooper cost $100. Sold mine, #13, for $100 three years ago. They just don't quit working.

[Bill Cummings]

The original snooper cost $100. Sold mine, #13, for $100 three years ago. They just don't quit working.

Thanks.
Looks like I'm off the hook selling it since Al sold his equipment. He is pursuing Part 103 trikes now so as not to deal with a bunch of snipping hang glider pilots.