DIY 3D Arduino Powered Printer Build

3D printers are all the rage these days, and are coming down in price gradually, but are still a bit out of reach for many.

So many capable electronics and maker hobbyists have turned to re-purposing all sorts of things to build their own 3D Printers on the cheap.

Here’s one great example (though he uses a number of prefab things like stepper motors, extruder nozzles, and Arduino boards).

The tutorial is in three parts, and is pretty complete, including showing how to program the Arduino, and actually use the printer to create parts. (Humorously, he actually uses the printer with temporary “duct tape and bailing wire” construction to make the last few printed parts brackets and then replaces them into the machine!)

Credit: RZTronics

Reflections on Electronics Parts Searches and China

I’m currently looking for parts to build a HF Antenna Analyzer from a much passed around plan by Beric Dunn, and the search has been somewhat difficult. The search has led me to start thinking about how dependent we are on China for electronics parts.

On the one hand, it’s great we can go to sources like AliExpress, BangGood, GearBest, and dozens of other Chinese companies to get parts inexpensively as hobbyists.

But on the other hand, many people in the “maker” space are rolling their own electronics as prepping activities, such as building battery packs for solar power.

So what happens when your supply chain stretches all the way to a country that is actively stealing product designs from US companies, and has been caught installing spy software/spy hardware in products they produce for us?

Food for thought.

Are there reasonably priced alternatives for parts and small run PCB’s in the United States?

If not, could someone make a go of it in a cottage sized industry, perhaps with desktop sized PCB milling machines?

Something to research.

DIY Portable Power Box Solar Charge Upgrade

Recently I finished building my first portable power box in an “ammo can”, and have been charging phones and testing radios with it.

However… now it’s time to top the battery off, so I’m upgrading the box with a charge controller, and external port to plug in a solar panel.

Here’s the video tutorial I’m following to upgrade.

Credit: JDS Outdoors

Parts Needed:

The solar charge controller used will only handle up to 7 amps of current, so make sure your solar panel does not exceed that output, or you’ll need a heavier duty controller instead.

Reviving Lead Acid Batteries with Epsom Salts

In this tutorial video from Car Groves, you’ll learn how to rejuvenate a dead lead acid battery by using Epsom salts to get rid of the scale that builds up on the battery plates over time.

This is a bit time consuming, but good to know in case the civilized world goes boom and you can’t run out and buy another one easily.

Or maybe, you’re just tired of ponying up another $150 for a battery…. either way, now you know why they want the battery “core” back!

Via Car Groves

Powerwall Battery Pack Construction with BMS

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.

via Jehu Garcia

Antenna Theory – UnUn Transformers for Impedance Matching

Baluns and UnUns come up frequently when discussing antennas of different types and matching feed point impedance so you don’t burn up the final stage transistors in your expensive radio.

This video contains one of the best explanations I’ve seen so far of wave propagation in antennas, and how to build a transformer to convert and match impedances.


Calculating Power Ratios from Decibels

Decibels have never really made a lot of sense to me, though I memorized the relevant numbers to pass both my Technician and General class ham radio operator license tests.

I mean, 3dB = 2:1, 6dB = 3:1 and 10dB = 10:1? What sense does that make? And its bothered me that I didn’t know how to figure out where those numbers came from.

But I’ve finally found a formula to do the conversion from dB to a power ratio that I can remember and makes a sort of sense, especially when dealing with partial decibel numbers like “2.8 dB”.

So here it is:

Ratio = 10^(dB/10)

Research Gate

So using 2.8dB from the 2016-2020 Amateur Extra question pool (E9A15), 2.8 dB converts to 1.905 power ratio for calculating effective radiated power.

10^(2.8/10) = 1.905

And that means that a station with 150 watts of transmitter power and 2dB of feed line loss and 2.2dB of duplexer loss plus 7dBd antenna gain has an effective radiated power of 286 watts.

Total gain = 7 dBd – 2 dB – 2.2 dB = 2.8 dBd or a 1.905 power ratio.

150 watts x 1.905 = 286 watts effective radiated power.

Simple! Now I can move on to the next question in my study guide. Just 55% more to go!

Addendum: See solving decimal exponents here to deal with the 10^0.28 part of the equation without a scientific calculator.

Homemade Soldering Iron Tutorial

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.

For some of the other homebrew soldering iron options, follow this link to YouTube!

Apparently, this is a fairly common thing to make when you might not be able to get to your commercial soldering iron, and have a few minutes and the parts.

WSPR: Weak Signal Propagation Path Reporting

WSPR (pronounced “whisper”) stands for “Weak Signal Propagation Reporter”. It is a protocol, implemented in a computer program, used for weak-signal radio communication between amateur radio operators.

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.


Applications for WSPR

The protocol was designed to test propagation paths on the LF, MF and HF bands. Also used experimentally at VHF and higher frequencies.

Other applications include antenna testing, frequency stability and frequency accuracy checking.

Usually a WSPR station contains a computer and a transceiver, but it is also possible to build very simple beacon transmitters with little effort.

For example simple WSPR beacons can be built using the Si 570 crystal oscillator (see PDF for kit links and schematics), or Si 5351 (kit available here).

The Raspberry Pi can also be used as WSPR beacon.

Photo Credit: Gerolf Ziegenhain – Own work, CC BY-SA 3.0

Article Link: Raspi as WSPR Transmitter
Source Code:

Here’s another example DIY WSPR beacon project video:

Source Files for Project on Github

Download WSPR Software at the Official WSPR Site: