How do I go about creating a new circuit?

Last modified December 2, 2020

How to make home electronic projects?

Does it ever happen to you that when you start a circuit you do not know very well what you want it for or what purpose it will have?

This is an important point because, although it is true that sometimes you cannot know in advance what use you are going to give it, it is important to have a certain idea to be able to prioritize each step or put more or less effort in each aspect.

  1. Just for the fun of it, to overcome the challenge, see what works and learn along the way
  2. For see what results it gives and if it is good to pass it to "production" and install it definitively
  3. With the idea, from the beginning, of give it real and continued use

Usual process to make an electronic circuit:

  • I do the tests as quickly as possible with the sensors I want to put, one by one, and see if everything works fine
  • I wonder which sensors I am going to combine based on how well it suits me to combine those specific sensors (due to the suitability of the location, available pins, box, etc.)
  • I think in which box I am going to put it so that it has a "more or less" professional finish and that they are not a swarm of cables hanging around the house

Oddly enough, of the previous points, the one that usually gives me the most headaches is the box. In addition, the box, in many assemblies, is usually an "active" part of the assembly since I take advantage of it for the wiring of the circuit.

I like that things that remain «fixed in the house»Have a good ending, and I am quite a perfectionist (although many times it remains an intention), so I am never satisfied with the result obtained.

The reality is that I usually say «I leave it like that, for now, which is acceptable, and as soon as I have a while I improve it»And, well… it usually stays that way.

It is clear that when I only want to mess around, and if the design is not very complex, I do it in any way "in the air", on a breadboard or a perfboard.

A practical example of a home electronics project

The best example I can give at the moment, is the project that I am finishing and of which I have already published some blog posts about its parts: a node for the master bedroom, based on ESPEASY with an infrared emitter to control the air conditioning and a CO2 sensor (you have a more recent CO2 meter project here).

Of course, before doing anything with hardware or firmware, you have to do a little research and make preliminary decisions:

  • What functionalities I want him to have the pot?
  • How am i feed?
  • What components will I use to get these functionalities?
  • Am i going to design a box that can 3D print? A standard box?
  • How much do i love myself spend?

With all these decisions already made we can get our hands dirty.

Practical execution of the electronic circuit

You know, "divide and conquer«. Personally, what works best for me is to divide the project into several smaller projects that I can do separately.

  1. Infrared emitter
  2. CO2 sensor
  3. Put it all together
  4. Tests
  5. Box

First I rode the circuit only with infrared emitting diodes and I tested and adjusted the firmware so that it worked properly independently. Later, and once satisfied with the operation of the infrared emitter, I did the same with the CO2 sensor, assembling the hardware and adjusting the firmware so that it worked correctly.

The next stage is to put it all together and make sure that both hardware and firmware are working properly, doing all the tests that are necessary and leaving everything running "dirty."

The testing part is very important. Nothing worse than having a seemingly finished thing and then realizing that something is not working properly. No time to save on testing.

The next important step was box. For this, I started from the standard box that I usually use for most of my assemblies with NodeMCU, and that I print on my 3D printer, but I modified it appropriately in size and added the necessary openings; two for the two infrared LEDs that I was going to use and another two for the two "hot" zones of the MH-Z19 sensor that I was going to mount.

The last step: fit and wire everything inside the box and redo all the necessary tests, before installing it in its final location.

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