This 3-part video series from RZtronics shows how to home-build your own Arduino based 3-D printer. Uses a lot of purchased parts but there’s still a lot of savings over the expensive commercially available 3D printers.
The Arduino software, parts lists and sources can be found below the video on YouTube OR here at the RZtronics website.
Morse code is no longer required for an amateur radio ham license, but its still beneficial to learn.
I found this neat system created by the fine people at Ham4All.com to teach the basics of Morse Code (Also referred to as CW or Constant Wave) in about an hour.
The SHAPES of the letters are used to remember the pattern of “dits” and “dahs” (dots and lines) that make up letters and numbers.
There also is an app created by the same people to help you practice.
Of course this is just a temporary crutch to get you started remembering enough to practice, and eventually you’ll want to just hear the letters like you would a second language without the interim translation step.
Looking at the schematics for the Minima Transceiver, I notice that there are some inductors included in the top left corner of the schematic, and that the photos on the author’s page appear to show home wound inductors on a toroidal core.
This post is my notes on how to calculate the amount of wire needed and wind those components.
I also need to know how many windings are needed on a core.
The ARRL website has this handy PDF on winding air-core inductors, which includes the calculations for that type of inductor, but since I want to use a ferrite toroid, this is not the math I need.
So let’s see what else is out there…
Here’s a calculator that can calculate inductance per turn:
The above calculator needs the relative permeability of the material the core is made of. I found this handy table of magnetic permeability by medium over on Engineering Toolbox.com which will help with the calculation.
Here’s an alternate calculator that works on specific cores by part number and material:
This project is based around the recent HF1 QRP transceiver by Ashhar Farhan, VU2ESE. The transceiver is an interesting SSB design with wide tuning range from 0-30MHz and should cover several amateur bands. The schematic for the transceiver can be found on the Minima mail list in this post with a PDF attachment.
After a front end 0-30MHz filter, the transceiver uses a 45 MHz first IF and a 10 MHz second IF. The famous bi directional amplifiers are used in the bi directional SSB sections of the radio.
Studying for the General ham license, which is the next step up from the Technician’s license has led to some interesting (and entertaining) “ah-ha” moments for me regarding the design of radio antennas.
Prior to dipping my toes into the ham test question pools, I’d always thought of antennas as passive equipment, responsible for receiving signals only. (Keep in mind I have no prior background in electronics.)
But it transpires that antennas not only receive, they also SEND signals and as a result short mobile antennas like those used for a car rig can develop quite a bit of voltage at the terminal tip when transmitting.
This brings me to the ah-ha moment– those little balls on the end of an antenna tip are called “corona balls” and their PURPOSE is to prevent high voltage discharge from the antenna tip! They are not just decorative!
Who knew, right?
I remember from my childhood, some of the old cartoons having an animated beeping antenna where the corona ball actually lights up. (A corona is a halo of light– or electricity.) And knowing now that the corona ball prevents high voltage from dangerously flying off the tip of an antenna, that cartoon suddenly makes so much more sense.