There’s a guy named Jehu Garcia in California who’s made it his mission to recycle laptop and other batteries in the United States instead of sending them back to China.
One of his ongoing projects is building DIY power walls (similar to the commercial ones made by Tesla at a premium price) using these reclaimed batteries and modular PCBs and commercial battery holders.
This is a lot easier than soldering the cells together with nickel strips and making your own brass buss bars.
Here’s his tutorial on putting together the battery packs, including how to match cells, and even build the ribbon cables for the battery management system monitoring.
Just found this great tutorial on how to make your own soldering iron from bits of wire, fiberglass tubing, nichrome wire from a hairdryer, and a rough cross section of a branch.
When I was searching to find the video again to place it above, I found that there are MANY MANY different versions of the home made soldering iron made with slightly different parts, so there are lots of options.
WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions. Transmissions carry a station’s callsign, Maidenhead grid locator, and transmitter power in dBm. The program can decode signals with S/N as low as −28 dB in a 2500 Hz bandwidth. Stations with internet access can automatically upload their reception reports to a central database called WSPRnet, which includes a mapping facility.
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: