2,5 PWM

Athough it seems pretty obvious to me, i didn't found any information about this method in sources, despite seeing 2 hours lectures about cosine error. How to make let's say 2,3 PWM output? You open bank account. We can only set 2 or 3 PWM value, so let's say, that at the beginning we set 2. After 58 ms we realise we are in debt. Our bank account saldo is ( 2 - 2,3 ) * 58 = -17,4 to pay this debt we set PWM at 3 and expect our saldo to be positive in next step, what will force us to set value at 2. And this while (1) certainly.

If you know dead scientist who patronises this method, let me know in the comment.

Peltier controller

This is what my Peltier controller looks like at the moment. It's rough, but it’s just prototype.

Safety is number one priority, so:
IP 20 and appliance class III

Optocoppuler

Plugs

Plugs are very important, because pulling cable may cause bad touch on our board.
Few layers of stolen nail polish may not seem beautiful, but seems like making legit IP67... as long as you are not moving it. It cracks, and need a replacement for something more flexible. It was flexible for few days, but now it isn't. No hot glue is not a good idea. You may fail to cover metal correctly. You need to put few layers of some flexible glue. Looks like I need hardware store shopping, unless you let me know in the comments about better way.

To power all this I used the most primitive buck converter with diode bridge and multimeter says it's extremely linear. Looks like the very next step is to make a container temperature of which will be regulated.

Order on a board

You want to have order on your breadboard? You have whole lot of connection to make? This DIY is for you. This breadboard is in order. You don't believe me? What if I tell you that every cable has its pair of colours?
You need:
Few non-red, non-black 0,25 mm2 cables
0,5 mm2 Bootlace ferrules

Take every pair possible including pair of cables same colour, so blue-blue is also a pair.
Twist uninsulated end of a pair and crimp it.

Turn ferrule 90° and crimp it as in the picture.

Do that on four sides. If you do everything correctly you should have 0,7 mm pin, that should tightly fit in the board. I'd rather like it to be standard 0,65 mm. Should you know a method, that don't include grinding, please let me know.
That custom made cables should make you sure, that the cable won't fall and there will be only one cable of pair of colour.
And the most interesting part. If you want to connect LEDs to output pins via resistor, you can hide it in a cable like this.

This way you don't use precious fields on your board to put resistor in it.
The more radical way would be soldering board on a PCB, to connect it to some terminal blocks and put cable under the board. I have a lot time to think about it while doing other stuff.