🎓 Doc Freemo 🇳🇱 @freemo@qoto.org

I have started working on my ROES SWR meter again. Hope to finish the v2 of the project in the next week and get some PCBs printed.

This has been int he making a long time now. Always wanted a super high-tech SWR meter.

#HAM #Engineering #RF #HamRadio #RF #EE #Science #Electronics #Arduino #AVR

Well im back in my Philly home for a bit. I must admit I really missed my beast of a computer and my Electonics lab.

#EE #Electronics #Computing #cs #it

I wanted to kick off the #QotoJournal hashtag by sharing a free open-source book I started writing some time ago...

I started writing a book in an attempt to help explain how to do circuit analysis by hand. Originally it was going to include both time-domain analysis as well as frequency-domain analysis. The book is incomplete and I never got to cover the time-domain but has several complete examples showing frequency-domain analysis on many common circuits. I’ve gotten some compliments over the years, particularly from HAM radio operators, on how useful the book has been to them. I’d like to share here what I have so far in case anyone might find it useful.

As a side note if anyone would like to revive the project and work with me on expanding and completing the book it would be most welcome. Please feel free to contact me. In the meantime here is the compiled book in its current form. I don’t currently have the latex source code published anywhere but if there is any interest I will happily publish it and open-source it on github.

Here is a direct link to the book: https://discourse.qoto.org/uploads/short-url/tFY6qFBUnmFFVdnBErQ8mJdZuBF.pdf

You can also view the book as a feed in my blog here: http://jeffreyfreeman.me/frequency-domain-circuit-analysis-tutorial/

If you wish to comment or discuss it there is a discourse post for it here: https://discourse.qoto.org/t/frequency-domain-circuit-analysis-tutorial/41

#ElectricalEngineering #Electronics #Science #HamRadio #Radio #RF #math #mathematics

Here is a free book (Draft) I am writing (slowly) explaining how to analyze AC electrical circuits in the frequency domain.

Anyone who wants to learn the math behind electronics and specifically AC or RF circuits should download it and check it out,

https://discourse.qoto.org/t/frequency-domain-circuit-analysis-tutorial/41

#electronics #EE #science #rf #circuits #ElectricalEngineering #HAM #science #AC

Kina excited, my Protowaffle project is in the process of making its first Sale to an electronics retailer. Just waiting to hear how many they will buy. Lets hope it is a big sale

Also still offering free samples If anyone wants some free samples let me know, here is some info on it: http://protowaffle.com

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

Recently uploaded a copy of a book I was writing to help teach RF/AC circuit analysis. I never did finish it but the first few chapters I wrote has some really useful explanations. Anyone trying to learn electronics should take a look.

https://discourse.qoto.org/t/frequency-domain-circuit-analysis-tutorial/41

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio #Discourse

Now that the #QOTO Discourse server is fully working, including the math rendering, I can start adding some content to it.

For my first post I wanted to share a tutorial I wrote on how to do frequency-domain nodal analysis on electronic circuits.

Here is the link:

https://discourse.qoto.org/t/nodal-analysis-tutorial/36

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio #Mathemathics #Math #Maths

If anyone wants one of my protoboards for free to try out don't forget to send me a message. Here is the original post:

https://qoto.org/@freemo/102467854068623471

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

I just finished a first draft of my Protowaffle Datasheet (electronics prototyping board for surface mount). I could really use any feedback before I go live with this.

https://git.qoto.org/protowaffle/protowaffle-one-datasheet/-/jobs/206/artifacts/file/ProtowaffleOneDatasheet.pdf

#OSS #opensource #Science #STEM #RF #EE #Electronics #Engineering #ElectricalEngineering #RFEngineering #HAM #hamradio

Sneak preview of the Protowaffle website my buddy luuk us working on. I love the colors.

Feedback, ideas, al welcome!

#OSS #opensource #Science #STEM #RF #EE #Electronics #Engineering #ElectricalEngineering #RFEngineering #HAM #hamradio

So I recently got a few thousand boards printed up for my protoboard design. Tested them on a few circuits and im amazed how well they work. I'm writing the datasheet now and we will begin selling on digikey, mouser, and many other big names soon.

In the meantime any EE people out there want a free board? We are going to hand out a few hundred for free to get people interested.

Here are some past posts I made about it for some background info. I've also attached an image of the final boards.

https://qoto.org/@freemo/101518455796695415

https://qoto.org/@freemo/101517564046276857

https://qoto.org/@freemo/101471853619646546

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

Now that I finally got my Electrical Engineering workbench in place I had some time to work on coding up a e-ink display. I finally got it successfully displaying images. This display is 7.5 inches and can do red black and white.

#electronics #EE #ElectricalEngineering #Engineering #Science

An image showing how the protoboard I designed is laid out as well as a picture of the printed board and my Frequency Counter design soldered to it as an example. I also attached the schematic for reference.

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

The first draft of the PCB protoboard I designed arrived. It is more beautiful than I could have imagined.

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

The latest version of my frequency counter prototype using a Manhattan style construction.

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

There is a sort of beauty in the order and chaos of a prototype design.

Just finished soldering together this frequency counter frontend.

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

After several more hours of cleanup the Prototyping SMT board I've been working on is finally done. I attached both sides of the board below.

Here is a link if you want to order a few for yourself. If anyone is really interested I can even send a few out for free to try it out: http://dirtypcbs.com/store/designer/details/freemo/6230/smt-smd-prototyping-board-tssop-20-sop-20-sot-23-6

I havent decided yet if I want to make this open-source. I probably will.

It can act as a simple breakout board for either a single SSOP-20 or x2 SOT-23-6 chips. To use it as a normal breakout just use solder to bridge the 20 connectors on the right and left and sides of the board and it will be a normal breakout (which each pin on the chip going to one of the header pins directly).

Here is the full description.

However there is also a SMT grid on the front and back so you can solder a full circuit onto the chip and arbitrarily have any point in the circuit wired to the various pins. Which makes for very handle little modules you can solder up and reuse.

I also added two power rails for ground and VCC down the middle with vias to both sides of the board. I also added other connectors around the edge that add in vias and wires connections to the opposite side of the board. Should be very useful.

One other little hidden feature is the spacing. Most of the pads are the perfect size to fit most two terminal SMT components (x4 0603 components can solder onto a single pad). But because the pads down the middle are offset it is also very easy to solder on SOT-23 connectors that have 3 terminals. So you really can solder almost any sort of SMT components on here.

Next step will be to build a larger protoboard that can accept modules like this and similar to create more advanced circuits.

Attached are images of the top and back of the design.

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #hamradio

My friend gave me a fully functional antique frequency counter. I don't need it with my oscopes and spectrum analyzers, but you have to admit this thing is pretty sexy.

I'm pumping a 12 millivolt peak-to-peak sine wave into this thing at 10MHZ. That seems to be the bottom of it's resolution range. Much below that and the counter drifts. Not sure if that's the counter or my equipment though. I am using a cheap signal generator for this test.

#EE #Electronics #RF #Radio #HamRadio #HAM

Cleaned up my Directional Coupler project. Labeled the ports and even added the electrical characteristics at different frequencies on the bottom. I then added a coat of lacquer resin to seal in that beautiful copper color (which otherwise would go brown as it oxidized).

The final result has a sort of beauty to it.

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #HamRadio

If anyone is curious here are the characteristics of the Directional Coupler I just posted. The top line is the dBm on the forward port and the bottom line is the dBm on the REFL port for a 0dBm input signal. The markers for the common radio bands.

#RF #EE #Electronics #Engineering #Science #ElectricalEngineering #RFEngineering #HAM #HamRadio