de NV5F - FInally some good progress!

[Boovtech]

Hi Cubesatsim fans!

I began acquiring parts for this project last summer, however due to lots of other things going on, I did not really begin building in earnest until the late spring of this years when I decided it was time to finish ordering parts - before they were al gone - and get started!

This week I started a new main board after having made it to the stage of testing the old one after installing the eight sensors. I very quickly understood why the newer version of the boards had a place for a sensor test lead and that the instructions also suggested the use of right angle sockets for installing the senors. Several of my purple sensors on the first attempt seemed to be bad. There may have been other errors involved, But after successfully setting up my ground station and thinking I was on to finishing the main board, I was a little discouraged by the results of testing my main board because my sensors were all soldered directly to the board and getting them off would have been a chore and troubleshooting seemed almost impossible.

It was suggested that I get the larger blue INA219 boards which tend to be more reliable and to simply start over with a new main board. I found that others had already successfully used these boards with very little need for modification to the boards themselves. Despite this I was still overwhelmed by the task of essentially starting over. So while I was waiting for a new board and a few replacement parts to trickle in, I worked on it in my mind and took the time to see what others had done. My version is a sort of combination, and I found it went much quicker since the Pi and the ground station were already set up!

Please check out the photos at the end of this post.

Before installing the sensors I tested them all - 10 blue boards. I also tested 10 purple ones and found that they all showed good. Since I had already set up my ground station, the testing was simple with Foxtelem running. I used the blue ones because - despite their larger size - they have a better reputation in general. I decided the purple ones can be backups or for experiments or to give to others who are undertaking this project. I also decided to use a combination of regular and right angle sockets. Then if a sensor of either color failed I could just replace it. I have plenty of break apart pin headers to spare for mounting new sensors.

I used the right angle sockets on the bottom of the board where the sensors need to sit low enough to clear the Pi Zero. I also took the precaution of putting electrical tape on the ones that sit right underneath the Pi to prevent any shorting. There's lots of metal that can touch other metal under there! (even with these two cards installed upside down as is required when using these right angle sockets.) On the top of the board I used the regular tall sockets and pin headers, kind of in reverse oh how Mike did them. I think the only alteration I will have to make to accommodate the blue sensors is to Dremel a notch in one of them so it will clear the standoff during the board stack (Mike has good photos of this in his post). The boards all sit high enough to clear the diodes and the SMT connectors.

Now if a sensor fails or if I want to try a different senors with a smaller form factor, it will be as simple as unplugging the one that is in there and replacing it. That is a load off my mind.

The next thing I tried was - I believe - a very useful approach for anyone, especially someone less experienced. First I installed all the sockets and then I installed the sensors. I did them one at a time and checked each one with Foxtelem before continuing. This seems cumbersome: shutting down and removing the Pi between sensor installs - especially on the bottom of the board. But I found that it kept me clearheaded about what was going on. It worked pretty well, and when I got to the sensors on the top, where the placement of the Pi is not an issue, I found I could leave the Pi on and transmitting DUV mode as I soldered each sensor to the pin header and bridged the right jumpers and then plugged it into the proper socket. If it was good, it came up on Foxtelem in a few seconds and I could go on to the next one. It was also a very gratifying method of working. This all went pretty well, and then I moved a solar panel around to test each sensor and found that they all functioned properly.

After doing the sensors this way, I would even suggest that it might be helpful to set up the ground station before part 2 of the main board build, then it could be used in this way to test the sensors as they are added.... I found it a great way to get a handle on what's supposed to be going on one little bit at a time.

I was on such a roll after this success, that I finished the main board and tested all the sensors for current with a solar panel, and now I have a "nominal" main board!

I took my "half built" sim to Moon Day at Frontiers of Flight Museum in Dallas today - where I worked the AMSAT booth -and had a nice time explaining what I have learned about satellites to others This experience so far is a fine example of how an epic fail can be more valuable than getting it right on the first try. My explanations of how a satellite works would not have been possible without all that I have learned in the past month, getting ready to build it all over again

I'm looking forward to building the payload board next week!

I hope this helped some of you out there.

73
Virginia