Same here. Nerd blood runs deep in families.

(When the power brick blew out for my Atari, my dad simply cut open a random spare and re-wound the transformer to match the correct voltage. It was the neatest thing I had ever seen at that age.)

Any time! Just learn what you can now and pass the knowledge forward later.

It might be worth it for you to get a ham radio license. If the low power modules work for what you need, that is just fine. For the distances you are talking about with cattle fields, being able to legally transmit at over 1000 watts could have perks. (I jest, but having a little more power, in the 1 to 2 watt range, might be practical.)

At a minimum, a portable ham radio might be a good safety tool depending on the size of the ranch. It would be hella more reliable than CB as well.

Lol! I suppose the million dollar question is if you are generating interference. You are allowed to have a shitty design that works as long as you aren’t causing grandmas pacemaker any problems.

That book is a great start, actually. AC theory is critical in understanding RF circuits.

I noticed there were dedicated sections in that book for LC/RLC circuits. In regards to RF, you might see those referenced as resonant tank circuits, so keep that in mind as you move forward.

You aren’t going to see too much about impedance matching until you start working with transmission lines, as far as I know.

I just looked this up and read through it and it seems like a good intro. It’ll be confusing unless you have a basic understanding of AC: https://resources.system-analysis.cadence.com/blog/msa2021-understanding-impedance-matching-in-transmission-lines

Start looking for YouTube videos with Eric Bogatin. He is a professor at CSU Boulder and has re-written the book on proper PCB design. (He does have a book, but he debunked a ton of old theories on high frequency board design and signal integrity.) If there is anything you must do, is follow his work on ground and power plane design or anyone that references his work. If someone uses a ground plane to just “fill in gaps” or have it act as a generic fix-all “shield”, ignore them. (Many RF/HF myths came from the way boards were fabricated, not because of a specific circuit function.)

Once your signals get past a certain speed, you need to learn how electricity actually flows while understanding that both AC and DC theory applies. If you didn’t know that energy flows in the field around a wire, you probably need to step back a little before you step forward. (Reference Veritasium on YouTube: The Big Misconception About Electricity )

You don’t really need to get into heavy RF theory, but it helps. If there is anything you must learn about, it’s impedance matching and why it matters. To summarize quickly, if there is an impedance mismatch between your transmitter and your antenna, you could easily blow out your transmitter due to excessive power draw and signal reflection. (That is somewhat rare for low power devices, but not uncommon once you start to transmit above 5-10 watts.) If a device needs an antenna, use it, even if were are talking about something as common as WiFi.

For your first designs, respect trace lengths and recommended components. Most of all, respect the keep out areas around an antenna diagram and ensure your ground plane is properly designed and away from the antenna. There are many shitty designs that do work, but you want to strive for precision for your first few iterations.

Also, decoupling becomes more than just a thing to do that might improve stability of your MCU or other components. It’s entirely possible to get the rest of your PCB resonating which will cause all kinds of noise. This is partially negated with proper decoupling.

High frequency design just takes a little more care. Just remember the basic saying: Everything is a resistor, capacitor and inductor.

Now, if you just work with modules (and ESP32 with an integrated antenna comes to mind), almost all of the hard work is done. Make sure you have proper clearances, slap the thing on a board and you are good to go.

For the absolute basics, impedance matching with proper antenna length is what you need to learn first. (Receivers are much more forgiving than transmitters, btw.)

I am fully aware that some key details are missing here and just summarized as best as I could. If something I said turns out to be misleading, that isn’t the intent and I apologize in advance. The intent was just to kick start more curiosity.

Edit: RF design and high frequency board design share some design considerations. Not all signals on an RF project are going to be high frequency and not all high frequency designs use RF, but, all high frequency designs can quickly become RF designs.

Also edited a time or two for clarification, grammar and spelling.

piece in the pic is just found on the floor

This checks out. Even with all of my storage and shelving, I have found the floor to be a nice place to go parts shopping. JST bits are at the top of the list to find, usually. (What was that? You never bought any? You’ll find some, don’t worry.)

Do you need a bit of wire to patch a trace? Take your shoes off and walk around a bit and you will immediately find a lead you clipped off a through-hole component in about 15 seconds, even though you vacuumed 6 times since you lost it.

Bad bot.

Jesus is supposed to be dead. If you are meeting up with dead people, you have issues.

Like someone else said, pull all the LEDs. There is no point to them if you don’t need them. Just because a pin is set low doesn’t mean it’s completely off, so cut any unused paths to ground to be sure. LEDs still have to reach a specific forward voltage to turn on, but they could still be passing a fractional amount of current.

I believe the internal pull-up resistors are 10k, so if they are enabled, you can disable them and save a few more fractional pennies. (Maybe 3uA per pin if the pullups were enabled to start. Lulz.)

From a software perspective, you just need to keep the MCU in sleep mode as much as possible. Rely on the internal timers to wake up and sleep the MCU and make sure that the main loop is looping as slowly as possible.

That MCU should have an internal oscillator, so test it to see if it saves you any power. Turning it on and disabling the external oscillator should drop the clock speed down to 8mhz and might save you a bit more juice.

I tried finding the video, but I cannot.

It’s the same concept as potting PCBs with black epoxy. Of course, it helps to be aware of heat sensitive components but China never cares about that.

Google for Epoxyseal 9000, if you want something proper.

Adding on to this line of thinking, maybe a thin plastic tube and epoxy to encase it with the solder joints. (Bonus points for using thermal epoxy, since it is a resistor after all.)

I have seen Bigclive on YouTube encase resistors and a diode rectifier in standard epoxy for use in lighting, so heat probably won’t be an issue now that I think of it.