🎓 Doc Freemo 🇳🇱 @freemo@qoto.org

A picture of a Radio Shack circa 1950. Its a shame self-repair is virtually non existent and shops like this and radio shack themselves, are quickly disappearing. I remember when I was younger you could go there and any electronics part you could imagine. Now they cant even give away what little inventory they have.

#electronics #EE #ElectricalEngineering #Radio #HamRadio

FYI to all my Electronics people out there.

Did you know you can represent capacitance and inductance with a complex number and by doing so you would incorporate ESR (equivalent series resistance) into your equations. Essentially you dont have to model with idealized components and add in the parasitics manually, you can add the parasitics directly into the capacitance or inductance of your components!

See the following equation in my blog and the subsequent explanation if you want some further details and examples: http://jeffreyfreeman.me/an-indepth-look-at-duals-and-their-circuits/#mjx-eqn-realcap

#electronics #electricalengineering #EE #HamRadio #AmaetureRadio #Physics #Science #QotoJournal

My article is finally up on reddit (had trouble getting the moderators to approve it for some reason). As a result it hidden for over a day. Any of you who are redditors check it out over there and if you like it give it some love.

https://www.reddit.com/r/electronics/comments/j1qku4/an_indepth_tutorial_about_modeling_circuit_duals/

#Electronics #EE ##RF #HamRadio #AmateurRadio #Science #Physics #Math #Maths #mathematics

For those of you who enjoyed my recent blog post on Circuit Duals and Magnetic Circuits I have now compiled a version of it in PDF if you want to keep a local copy or have it for reading on on an e-reader. Feel free to distribute the link.

https://drive.google.com/file/d/1fECh_IeFYBHoFuaw08zO2dkluZPunkP7/view?usp=sharing

For those of you who are just now hearing about it the article describes the idea of Duality in math, how it applies to circuits, how to calculate duals for systems of equations, and a few examples of circuit duals. It also goes indepth on magnetic circuits as a dual of electric circuits. There is an interesting blurb at the end about how to extract energy from permanent magnets as well.

If you prefer the more colorful blog link instead, which will also be the only place I make corrections or update it most likely, the link for that is as follows:

http://jeffreyfreeman.me/an-indepth-look-at-duals-and-their-circuits/

#Electronics #EE ##RF #HamRadio #AmateurRadio #Science #Physics #Math #Maths #mathematics #qotojournal

So two weeks working on this article about Circuit Duals and Magnetic Circuits and it is finally finished and published! Check it out!

Its about mathematical duals and how they relate to electric circuits. I cover several common circuits as duals and how to calculate duals. Bu I also describe a rarely known type of circuit dual called a magnetic circuit that uses the magnetic field instead of an electric field to do all the things an electric circuit can do and explain magnetic inductors and capacitors. It's pretty cool stuff, I even touch on how you can extract energy from the magnetic field of a permanent magnet to power a magnetic circuit (or an electric circuit for that matter.

http://jeffreyfreeman.me/an-indepth-look-at-duals-and-their-circuits/

#Electronics #EE ##RF #HamRadio #AmateurRadio #Science #Physics #Math #Maths #mathematics #QOTOJournal

Ok I think my article will be ready to be published tomorrow after I do one more re-read in the morning.

In the meantime I'd really appreciate anyone giving it a read and seeing if they find any errors please. I really could use some final eyes on this before I publish it live!

http://beta.jeffreyfreeman.me/an-indepth-look-at-duals-and-their-circuits/#the-voltage-current-dual-under-parallel-series-transformation

You can suggest edits direct on my repo or here, I will be happy to give a thank you link at the bottom to anyone who helps.

n the source for my blog:

https://git.qoto.org/freemo/freemo-site-beta/-/blob/master/source/articles/2020-09-22-an-indepth-look-at-duals-and-their-circuits.html.md

Its about mathematical duals and how they relate to electric circuits. I describe a rarely known type of circuit dual called a magnetic circuit that uses a magnetic field instead of an electric field to do all the things an electric circuit can do and explain magnetic inductors and capacitors. Its pretty cool stuff, I even touch on how you can extract energy from the magnetic field of a permanent magnet to power a magnetic circuit (or an electric circuit for that matter.

#Electronics #EE ##RF #HamRadio #AmateurRadio #Science #Physics #Math #Maths #mathematics

Help! From anyone interested in English, Physics, Math, or Science.

I have written a rather massive article in the hopes of teaching people with mid-level knowledge in electronics about the idea of Duals in mathematics, how that applies to circuits and the various types of circuit duals that exist

I also include a great deal of detail in the end about one very obscure and rarely studied circuit dual called the magnetic circuit dual, it is a circuit, like a magnetic circuit, but instead of current being the flow of electrons, it is the flow of a magnetic field through wires made of iron instead of copper.

I even touch on briefly how one can extract energy from permanent magnets and other details most people arent very familiar with.

The problem is the article is massive and I really could use some eyes on it. Whether its just to try to help me catch english mistakes, or if your not that experienced perhaps tell me the parts that are confusing, as I would like this to be accessible to people who may not be scientists and only know entry level electronics or science. any feedback from anyone at any level would be highly appreciated.

Keep in mind I couldn't find many good sources laying out the equations for magnetic circuits very clearly so I had to derive a lot of the equations myself, though the concept is well established as fact and many peer-reviewed papers have been written on it. But bear in mind there may be minor errors in my math as well, so that too needs some criticism, though the math should be fairly close to correct.

Anyway any input from anyone would be much appreciated.

The draft of the article can be found on the beta site for my blog, here is a direct link:

http://beta.jeffreyfreeman.me/an-indepth-look-at-duals-and-their-circuits/

Similarly if you find any mistakes you can message me here, or you can leave a merge request on the repo for the article, here is the direct link to the markdown file in the source for my blog:

https://git.qoto.org/freemo/freemo-site-beta/-/blob/master/source/articles/2020-09-22-an-indepth-look-at-duals-and-their-circuits.html.md

It is much prefered that if you have specific edits like english or math you do it as a pull request as it can be a huge pain for me to hunt down the specific part of the text you are referring to if you point out mistakes as replies here. However if your unwilling to do a merge request please still ping me here as I'd rather know than to just let it go unnoticed.

Anyone who helps I will add a thank you with your name and a link to your own site at the bottom of the article if you wish, this might help draw some traffic to your own site.

#Electronics #EE ##RF #HamRadio #AmateurRadio #Science #Physics #Math #Maths #Mathematics #English

I have been writing a blog article that is getting so big its a small text book at this point. Easily the biggest and more detailed blog article on a subject I have ever wrote.

The topic is Duals of Electrical circuits.

It takes me half the paper to even get to electronics, I start by trying to describe what a dual is in general terms, give simple mathematical examples, then go onto duals of systems of equations where I finally tie it into electrical circuits.

At that point I dive into a series of examples of different types of duals for electrical circuits, and then finally end with describing a magnetic circuit as a dual for an electric circuit, where the power sources become magnets, the copper wires are replaced with iron ones, electrical current is replaced with magnetic current (which is a propagating magnetic field), and then I explain each magnetic dual for each discrete component like capacitors, inductors, resistors, and transformers. Needless to say this thing gets really deep really fast.

If your interested in seeing the final result keep an eye out on my blog, should be released any day now.

http://jeffreyfreeman.me/an-indepth-look-at-duals-and-their-circuits/

#Electronics #EE ##RF #HamRadio #AmateurRadio #Science #Physics #Math #Maths #Mathematics

A fun article I just wrote explaining what the Reflection Coefficient is and how it can be used:

http://jeffreyfreeman.me/understanding-the-reflection-coefficient/

#Electronics #RF #Radio #Maths #Math #Mathematics #Physics #HamRadio #Ham #AmateurRadio

So for those of you following my #ROES project ("Ridiculously Over Engineered SWR Meter") which I've been active on the past few days I finally just sent the boards off to be printed for a prototype run. so V2.0 is officially released (though I may do a minor revision before printing up a large number of boards).

Attached are some screenshots of the final schematic and some renderings of what the boards will look like when its done. Its a 4 layer board though so many of the traces are internal.

You can find the files for this, which will be released as open-source, here:

https://git.qoto.org/roes/roes-hardware/

#Ham #HamRadio #Radio #RF #EE #Electronics #ElectricalEngineering #Science

So I fixed a few more mistakes in the the V2 schematic for my "Ridiculously Over Engineered SWR Meter". Attached is the new schematic.

You can find the files for this, which will be released as open-source, here:

https://git.qoto.org/roes/roes-hardware/

#Ham #HamRadio #Radio #RF #EE #Electronics #ElectricalEngineering #Science #ROES

For those following along I have made some minor corrections to the V2 schematic for my "Ridiculously Over Engineered SWR Meter". Attached is the new schematic.

You can find the files for this, which will be released as open-source, here:

https://git.qoto.org/roes/roes-hardware/

#Ham #HamRadio #Radio #RF #EE #Electronics #ElectricalEngineering #Science #ROES

I think I may have finally finished the Version 2 Schematic of my "Ridiculously Over Engineered SWR meter" or ROES for short.

Its basically an Arduino based SWR meter with an LCD display (not depicted here as that is a seperate shield). But it provides all the functions of a Vector Network Analyzer (VNA) and goes way beyond your typical SWR meter. The only thing it doesn't have that a VNA would have is a function generator, as it relies on the transmitter to do that.

Generally you'd hook a directional coupler into your feedline (I'll be providing that as a seperate kit) and then tie the forward and reflected ports into this shield.

#Ham #HamRadio #Radio #RF #EE #Electronics #ElectricalEngineering #Science #ROES

Another style of directional coupler I had worked on.

#EE #electronics #engineering #electicalengineering #rf #radio #ham #hamradio #amateurradio

The hardest part of building a directional coupler is seeing how pretty and clean it is and knowing you will need to seal it away with copper walls and it will never be seen by human eyes again.

This was one of the more fun one day projects I ever did.

#EE #electronics #engineering #electicalengineering #rf #radio #ham #hamradio #amateurradio

Someone hacked the security chip on a credit card in order to make a crystal radio out of it...

https://youtu.be/_z3KmFqtPXQ

#Science #QOTOJournal #ElectricalEngineering #HamRadio #Radio #RF #EE

What a great day on Ham radio. spent 4 hours having a round table QSO on the national calling frequency of VHF with about 7 people each coming in and out throughout. Most active I've ever seen VHF simplex around here, really fun.

I also have to get a QSO in on HF just to absolutely make sure the antenna is working well. Hit up a 300 mile contact right at the end on 40 meter right at the end too. So the antenna is definitely working.

Good Ham day for sure.

#Ham #HamRadio #Radio #RF

WOOOOOT back on HF frequencies... 80m - 10m by the looks of it.. 80m i really need to load the thing up but everything else it tunes easily.. gonna be surfing the air waves tonight!

#Ham #HamRadio #radio #EE #Electronics #RF

Anyone wanna do a WiresX QSO (C4FM Yeasu System Fusion) by any chance? I'm bored?

#HamRadio #Ham #Radio

So while my top-end rig is being repaired i decided to buy a new cheaper rig as a temporary standin. I decided to get a FT-991A. It has a waterfall display and can do digital voice on both HF and VHF/UHF which means it will actually still be useful to me after my main rig is fixed. Looking forward to trying C4FM over HF frequencies!

#Hamradio #Ham #radio #electronics #EE