Friday, March 30, 2012

Another SDR Post

I started putting together the hardware for the thermocouple amplifiers, but quickly realized I didn't have everything I needed. I needed some reasonable sized capacitors (0.47uf 10V or so) and a trimmer resistor. The closest I could find in my collection was a .10uf at 25V or .33uf at 1000V. I thought, crap, for less than a dollar, I should get what I need. That 1000V cap, while close to what I needed, was bigger than the chip. Board real-estate would be a challenge.  I know it is just a proof of concept, but I needed something better. I have some surface mount caps, but even those were all over the map, like 47uf, or 100pf, nothing kinda medium.

I was thinking a quick order at Mouser or Digi-Key and I would have what I need by Wednesday. Well, it would take a $25 minimum order, and I'd obsess over what else to buy for 5 days, and I wouldn't get what I need until next week. I had a coincidence happen on Tuesday. Traffic was awful, and I needed to try a different way home. I ended up in Farmers Branch. Tanners Electronics is right there. I thought I am close, maybe they stay open until 6pm. IT was about 4:50pm, and I was close, so I thought I'd go for it.

They are open until 6 Monday through Saturday. I could pop in there and get what I needed. When I got there, I was surprised. They had about the same collection of small capacitors as I did, .33uf at 1000V and some surface mount ones. I did find a couple medium ones, one disk, and one film and a small one, mylar I think. I bought an assortment, at least 2 of each, and a couple trimmer pots, spending all of $3, and I had them.

I haven't had time to do anything with them though. I hope to this weekend.

I've been thinking what a full system might look like. How about the Arduino as the engine controller and monitor. This is for the full FADEC system. Then a USB connection to a central hub, maybe an ARM controller running Linux. Another Arduino running DIY Drone air data computer, and IRS gyro package connected to the central controller over USB. Each Arduino would have their own blue tooth connection for sending to the display computers. Display computers would be Android tablets. I am not sure what the central system would do other than data collection. I guess it should share information, with the two Arduino's. Like putting in a TOGA button, the FADEC would run the engine up for takeoff power, then the autopilot would fly the missed approach procedure. The central computer would have some GPS and mapping software, unless that was outboard also (Android tablet may have that?).

Lots of planning and dreaming.

I said this was an SDR post. Well, here is the SDR info. Suddenly SDR hardware is down to about $20! You can buy USB tuner cards for PC's that have untuned front ends for $15-25 on EBay. There is software available to use them, and they are quite popular. They can tune anything from about 64-1700MHz and should work in almost any mode (even TV, since that is what they are designed for!). Reddit has a hardware compatibility chart. 

I ordered one, maybe, I'll have time to play with it. It sounds like it has most of the software written. All I need to do is plug it in and run some code.

I also found the LinuxCNC website. That might be my answer to the 3D printer I've been wanting to work on. Again, when I get some time, I'll take another look at it.

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