Juliean's Build Log


#1

I went through the Getting to Blinky video mostly to learn KiCad, but then decided, what the heck, might as well build the thing, haven’t done SMD in a while. Worked well, first try :slight_smile:


#2

Managed to get it mid-blink.


#3

Welcome and nice job Juliean! I noticed you commented that you hadn’t done SMD in awhile. What brought you to KiCad and back to SMD?


#4

Blinking is a good feeling! Soldering job looks nice here as well!


#5

So apparently I should have started this with an intro post. Oh well, doing things backwards isn’t unusual for me :slight_smile:

I’m strictly a hobbyist. I started playing with electronics in elementary school, with the old RadioShack “200 projects in one box” kind of kits. Computer Science degree in college, but pretty much straight software. Just one or two classes on computer architecture and such that touched on hardware. Then my career went into a very different, and non-technical direction, but have always been into tech. Kept my hand in on programming a bit by doing various small projects for the office, for some non-profits I’m invloved with, an occasional open source project, that sort of thing. Mostly PHP in recent years.

Around 2010 I discovered the modern maker movement and played around quite a bit with Arduinos, RPis, etc. Nothing very productive, just some small projects. Hacked a baby toy so we could restart the “falling asleep” music in the crib via a radio transmitter, that sort of thing.

Got my ham radio license in 2015 (KQ2Z), played with that a bit, but mostly just using the radios, not building.anything.

Have gotten back into electronics in the last few months, and want a bit more structured approach. My knowledge is very hit-or-miss, learning just enough to get done what I wanted. So I never know what I don’t know… I’m generally better at digital than analog. Firmware is easier for me than hardware. So I’ve been focusing on learning the analog world a lot. Currently reading through the “Art of Electronics” and also trying to work my way through “Learning the Art of Electronics”. This course seemed a nice complement to that.

I’m also working, very slowly, on a significant project - an APRS tracker for a High Altitude Balloon. By far the most complicated thing I’ve done, especially since I’ve set myself some tough goals on it - design everything from scratch, no modules, just components. Write as much of the code as possible - use as few outside libraries as I can get away with.

I have a rough mockup on a breadboard, and have recently ordered some boards from OSHPark to try out some of the sub-circuits. Still lots of code to write.

I was asked above why KiCad and why SMD. In the past, I’d used Eagle, but with the Autodesk takover and change in policy it seemed like the right time to move to an open source solution. That’s how I found CE - “Getting to Blinky” is about the best KiCad tutorial that I’ve found. Why SMD? Because most of the interesting parts these days are only available in SMD, and because in the HAB tracker project space and weight are at a premium.

So that’s me.


#6

Awesome, I like that you have a stretch goal of that APRS tracker. I think that even if you can’t make progress on it immediately, it gives you a template from which to discover which parts of your background you need to work on.


#7

Heh. That’s not even the real stretch goal :slight_smile: The real stretch goal is even more ambitious - I want to design a CubeSat. I doubt I’d ever actually build one, let alone launch one - I have neither the skills, equipment, or money to do so. But it’s a fun aspirational goal. And who knows? Launch costs get cheaper and cheaper every day.

The APRS HAB tracker came from that goal - it was one of the first system I wanted to develop, and HAB is a cheap way to test it. It’s the immediate goal, one I can work towards today.

So one additional constraint on the design is that it has to be space capable, at least in theory. While I don’t have all the necessary skills to do real thermal design for space use, I’ve been keeping this constraint in mind when selecting parts, etc. Good temperature rating, nothing obviously disqualifying, etc.

For example, I really wanted to use a PSOC chip as the main flight computer, but there’s indications out there that it doesn’t handle radiation as well as other ARM microprocessors. So that’s ruled that out.

GPS is another. I’d like to use a uBlox GPS module, but can’t find any evidence that they make space-capable ones (most GPS modules have a maximum speed limit built in, to prevent use in weapons). Venus GPS, otoh, is available in space version (with appropriate paperwork and at a higher price). So for the HAB tracker I’ll likely use the Venus, unless I can get in touch with uBlox and find out if they make unlocked versions. The hardware, interfacing, etc. are all the same, so it’s a question of which module to write code for.


#8

Welcome to the forums! This is very cool. APRS and high altitude balloons are things I’ve wanted to play with for sometime as well. I’m also a software developer with a ham license (KF6LMD). I’ve had a novice license for 20 years, though I’ve never really used it. My daughter and I are in the process of studying for our technician and possibly general license so we can do more with it. I recently stumbled on this site: https://www.qrp-labs.com/circumnavigators.html. I had no idea that there were so many amateur radio balloons circling the earth! That’s a really cool goal. And it would be a great way to slowly build up your circuits to eventually get to space on a CubeSat. I was also thinking of playing with WSPR in addition to APRS for sending basic telemetry.


#9

One of my inspirations on this is a friend who’s successfully done circumnavigation with an super light balloon - just two mylar party balloons, a tracker, and some solar cells (no batteries). He used WSPR, and is planning on adding APRS on the next version.

My interest is in APRS since 2m frequencies work well for space communications, whereas the HF frequencies at which most WSPR signals are used will, if I understand correctly, bounce off the ionosphere.


#10

As I mentioned above, I’m very slowly working my way through the Learning the Art of Electronics book. I’ve started blogging about some of the things I learned and had to create. Blog is here: http://kq2z.com


#12

Blog updated with two new posts. Sometimes, building the stuff needed to do the project takes longer than the project itself.


#13

That project box for the transformer came out great! I see what you mean when you said the prep work for these labs takes longer than the project itself. I’m also hoping to start on these labs later this year and this gives me at least some idea as to the work involved. Thanks for posting.


#14

I created the Teensy Adapter board from the CE Header project a while ago, just got the boards back from OSHPark. Here’s a composite image:

For the life of me, I can’t figure out why I bothered to flip the SCK signal to the front through a via. Could have left it on the back…


#15

Last night I had the chance to route the sensor board. Yeah, squeezing it down to 1"x1" was a challenge for sure. I did some of my routing different than in the video, since I used slightly different footprints.

I chose a larger capacitor footprint for the thermistor, so as to get the pitch correct. I also used the 0805 “hand soldering” footprints to make assembly easier.

All that meant it was even tighter, and required some different choices. I put a few of the decoupling caps in other locations. I also added a ground plane, just because.


#16

There’s a classic C mistake of using “=” when “==” is intended. Often like this:

while(i=0) {...}

Well let me tell you, it’s just as bad the other way. And takes forever to find the bug :slight_smile:

In this case, the code was something like

while(1)
{
   if(i>7)
   {
      //dostuff
      i==0;
   }
} 

For the life of me, I couldn’t figure out why it was right for the first 8 bits, and then wrong afterwards… :slight_smile:


#17

Grrr. I’ve been wanting to build the sensor board and teensy adapter, but the USPS seems to have lost my shipment from OSH Park.

It was supposed to be delivered on 3/15, the tracking site has no info since 3/17 where the last info is “en route to next facility”. Helpful that.

OSH Park customer service has been great - they are remaking the boards, gratis, using their swift service, so I should have the new boards soon. Hopefully.


#18

This happens to me now and then delivering to Germany sometime over four weeks delivery. Without fail, the day after contacting OSH Park support the boards arrive the next day. If I have a couple of boards in the pipeline, it is not such a problem. But you are right, the customer service are quick to react.


#19

And wouldn’t you know it, USPS just updated with a delivery date of today :slight_smile:

Hope it actually gets here.


#20

Updated the blog with some older labs. Still need to post about the actual CE stuff I did.