The previous week, I had started playing electronics.

But remember. It was still very timid theory, with scraps of paper:

We know: theory is good. But OK. The fun thing is more practice.

Suddenly, I received the cards that I had ordered. The opportunity to bring out my panoply of the perfect little Chinese.

So application, with a stencil, of the solder paste:

Micro-surgery to remove the components:

And the famous soldering pan − my favorite moment:

Brief. 4 pretty well-done little cards to test the electronics of our new Pioupiou:

Separated, it looks like this:

With the two AAA size batteries, the version with GPS on the left and the version without GPS on the right.

Well, obviously, I haven't even had time to test them yet. On the other hand, I have already found a good dozen things to correct. That's a pretty good sign.

Dear Santa Claus

In the meantime, I went into the office of a colleague who was a bit more of an electronics expert than me.

Discussed. Lots of ideas. He showed me things that won't work, and things that will work. In short, it was nice.

But I think the coolest thing was above all the office!!! Alibaba's Cave!!! The bedroom of my dreams!!!

Santa Claus, if you pass by... I've been very good this year 🙂

Oh no, it's already Christmas

Unfortunately, I didn't find what I was looking for. Or at least there were the right instruments, but not for the right frequencies.

Me, what I wanted to do was adjust my antenna. And for that, you needed a Vector Network Analyzer, which can operate at 868MHz.

It's this kind of big thing:

 And it costs about the same as this:

So I thought it was almost Christmas. (I counted!) And that all the same, I had been very good.

Brief. As I didn't have the money for the VW combi, I bought a miniVNA Tiny :

It is a small box developed by radio amateurs. It connects to the PC, and it allows you to have roughly the same functions as on the big machine. It's probably a bit less accurate, but since there are 2 less zeros on the price, it'll do just fine 🙂

By the way, I think it's really an essential tool for radio. There should be some in every fab-lab!

Do you receive me ?

So obviously, if I bought this it's because I had an idea behind my head...

I received the electronic cards for queuing and the antenna:

In theory, we have a half-wave dipole antenna which should be close to 17 cm. History of wavelength, and blablabla.

Except that in reality, the environment affects the setting of the antenna. And so with the electronic board and everything else, you need a shorter length.

For that, the method is simple: we make it too long, we test and we cut, and we test, and we cut, and so on. Until you have an antenna that works.

And thanks to the VNA, we can see our antenna better and better “ matched "

The graph represents the non-transmitted energy, as a function of the frequency. The lower (at 868MHz), the better.

Finally, it is won. We have an SWR (Standing wave ratio) of 1,12. It's excellent !

Our antenna has suffered a lot, but now it is on top:

So I note the ideal length: 14,5cm. That way we can make the next ones directly to the right size.

For fun, I still tested the antenna of the old Pioupious:

I measure a slightly worse SWR of 1,24, and a narrower bandwidth. But it's not too far from the specs announced by the manufacturer:

Brief. All that to say that our antenna looks pretty good. In any case, we can already say that it is effective in transmitting the energy it receives.

Now, we will have to test its directionality. That is to say, does it send well in all directions. But that's for the next episode.