Making things is not my forte. I love programming because if something gives it doesn’t destroy everything and make you start over from scratch. With making things… well. Let’s say I’ve learned my lesson. Actually several of them. On several different occasions. So this time loads of planning, no errors!
First I made a prototype on a breadboard because the setup is a bit different than the programming rig so I wanted to be sure it worked. I started by designing the entire thing on Fritzing. The final version will have less connections than when programming the attiny85 so it’s a good idea to make a schematic first so I don’t miss anything. I played around with all the components on a perfboard and I got them to fit in quite a tiny space. Now I was finally ready for some soldering!
My favorite method for soldering lots of little components is to put them all in their correct place, put another perfboard on top of that, attach it together with a rubber band or something, turn that around and then solder all the components in one go. Even such a noob as myself soldered everything together in under five minutes! (And this was my fourth time with the soldering iron.) No endless turning the board round and around and putting components in the wrong places! After that I just have to trim off the components and solder the connections and that’s it.
I was going strong and was sure to finish today, but when I tried the device didn’t work! After 1,5 hours of troubleshooting (Batteries checked, LED checked, connections checked, microcontroller retested in breadboard…) I realised that I had forgotten to solder pin 4 to ground. Noooo! But that will teach me to have my laptop in the other room and think that I can do without any visual aids while building something. Next time I’m soldering many components at the same time I’ll:
- calculate the exact number of connections I have to make
- write them each down on a piece of paper
- go through them one by one.
This circuit, the battery holder and the switch will all be encased in a Tic Tac box because I want Yago to
- see all the electronics
- see clearly that it is something build from not very fancy components
Fortunately the Tic Tacs came in a set of two. I cut a hole in the first one for the switch like this (picture on the left) and intended to squeeze everything else inside the box. Unfortunately it would mean that they would rattle around, which is something we really don’t want. That’s why I cut out part of the other box that I could use as a surface to mount everything onto. This way I can slide everything out, change the batteries, slide everything back in again and it will all stay firmly in place. (It’s also a plus that I can send the device without batteries, I’ll save about 5 euros on postage.) After hot-gluing the battery holder and the electronics in place, soldering the power connections and gluing the switch to the side of the box the device is ready!
And here’s a short video for the guys at Hackaday.
So that’s basically it! Taking into account that this is my first electronics project I’m quite happy with the way it turned out. The only setback happened right at the very end when I glued the switch on: apparently the glue and the plastic of the Tic Tac box weren’t compatible – the fumes from the over-generously applied glue ended up reacting with the plastic and forming a white, matte residue on the inside, but apart from that I‘m very satisfied with the way the device looks.
Now Yago will be able to pass some time learning about Morse code and decoding the message. If he really, REALLY gets into electronics, in a couple of years I can tell him that the beginning/end signal of the message is code as well and he has to figure out how to decode that albeit its speed!
Thanks for reading this, and until next time!