Over the last couple weeks whenever I had the time I’d work on creating a little DIY morse code keyer. After 6 designs (whoa!) I came up with the winner. The youtube video describes it all I guess. Basically it just uses a bar of aluminum which rocks on a metal pin. Thumb-screws on each side of the balance point (fulcrum?) can be adjusted to modulate the distance the paddle has to go down to be activated, and how high the paddle goes up when released. A couple springs (one pull-type and one push-type) help give it a good bounce between keys. Two potentiometers (knobs) control volume and frequency. I especially like the ability to control the frequency! A capacitor inline with the speaker helps smooth the output a bit too. It’s not professional, but hey – for a couple bucks of parts I made a functional keyer and had a blast doing it. Now I guess I should learn Morse code…

And some photos…





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I, Scott Harden, in my infinite restlessness and my limited sanity, hereby declare my next [potential] project. The idea is still in the earliest stages of development, and I have much to research (for example, I don’t even know if it’s legal) but it’s a cool idea and I want to try it. I know I’ll learn a lot from the project, and that’s what’s important, right? So, here’s the idea. I want to build an incredibly simple, low power radio transmitter that broadcasts data on a fixed frequency. Data is provided by (you guessed it) a picaxe chip! What data will it transmit? I’ll tell you! It could transmit… uh… err… um… okay it doesn’t really matter and I don’t even know, I just want to do this project! Maybe temperature and light intensity data or something. Who cares. Anyway, I want to put this whole deelibopper (temperature and light sensors, picaxe microcontroller, and transmitter) into a drybox (pictured). Once properly closed, this box will keep everything in pristine working condition by protecting against rain, heat, snow (not that we get much of that in Orlando), hurricanes, and perhaps even Florida panthers and bears (oh my). I’d make a glass (or plexiglas) window on the top so that light could get in, hitting solar panels, which trickle-charges the battery housed in the device as well. Pretty clever, huh?

My idea is to keep construction costs to a minimum because I’m throwing this away as soon as I make it. That’s right! Throwing it away. Parting with it – perhaps forever. My goal is to make it work so I can toss it in some random location (I’m thinking hidden on the roof of some building somewhere) and see how long it will run. Days? Weeks? Months? Years? How cool would it be go go to dental school, come back ~5 years from now, and have that transmitter still transmitting data. Super-awesome if you ask me. I’ve been poking around and I found someone who did something similar. They built a 40mW 10m picaxe-powered beacon (see photos and circuit diagram).

See the PICAXE chip in the center there? Remember, my ultimate goal is to learn from this project. I understand the basics of radio theory and amplitude and frequency modulation (AM and FM), but I’ve never actually built anything that does this. Yeah, I know, I could build a SoftRock radio like everyone says to do, but my educational grounding is in molecular biology. I know little about circuit-level electronics, electrical engineering, and radio theory… so my plan is to start small. This project is small enough to attack and understand, with a fun enough end result to motivate me throughout the process.





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I was poking around my digital camera’s SD card this morning and I stumbled upon a video I made a few weeks ago showing a little comparison between a rubber duck and a homemade 2m jpole antenna. Let me make a few things clear. When I built the jpole, I had ABSOLUTELY NO IDEA what I was doing. I’m not an antenna expert, I’m not a radio expert, I just get bored sometimes. The antenna has not been properly tuned. Yet, it works leagues better than my standard antennas. Even though its resonance properties leave much to be desired (untuned, remember?) I think its success has to do with its location. It’s on the balcony of my apartment, 3 stories in the air, and facing across Orlando (where most of the 2-meter repeaters are). The video itself isn’t that significant, but I wanted to post it so it doesn’t get forgotten.





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Two hours after getting home from work I’m already basking in the newfound carefreeness thanks to the successful completion of my thesis defense (and graduation requirements). Yesterday I went to skycract, early this morning I posted a schematic diagram of a basic circuit concept for a radio/microphone interface box with tone generating functions, and this afternoon I finished its assembly. It’s hacked together, I know, but it’s a PROTOTYPE and is for functional use only. What does it do? It’s complicated, and I described it in the previous entry. It’s basically just an exercise in microchip programming! Here are some photos…

Here’s that internal photo I promised I’d get posted yesterday…

Here’s the little setup with the main control unit and a DC to DC regulated power supply / serial microchip programmer I made.

Here’s the main control box. Notice the “2-way lighted switches” which I described in the previous entry (I posted the schematic). I found that proper grounding (floating pin prevention) was critical to their proper function. I’m still new to these chips, so I’m learning, but I’m making progress!

Getting a little artsy with my photographs now… this is the core of the device. It’s a picaxe 14m!

This is a ~? to 5v regulated power supply I built. The headphone adapter is for easy connection to the serial port. It has a power switch and a program/run switch (allowing use of pin 13, serial out) while still “connected” to the PC.

I wanted to toss this picture out there. I’ve slightly improved the connection between my radio’s coax cable to the ghettorigged jpole antenna I made.

I’m able to get relatively AMAZING results from this very unimpressive hack job, but it’s probably not likely to do much to my assembly skills (and lack of tuning), and more likely due to the fact that I have a beautiful unobstructed view of middle/southern Orlando from the 3rd story of my apartment balcony! I could probably wire up a rubber duck on a stick and get impressive results with that view! I’ll miss my reception when I move.

I just realized I didn’t post an image of the inside (complex wiring) of the device. Maybe later.





Additional Resources

I’m posting this information to the world hoping that someone else in a position similar to mine can benefit from the experience I gained through trial and error when trying to rapidly design/develop professional-looking QSL cards for as little cost and risk as possible. I Googled around for this information, but didn’t find anything too helpful, so I figured I’d share my story! For those of you who don’t know, QSL cards are like postcards which amateur radio operators often mail to one another after making long distance contacts. In addition to providing tangible proof of the communication, they’re cool mementos to tote around to show people / remind yourself who you’ve made contact with over the years. QSL cards display information bout the contact (time, date, call sign, frequency, signal report, etc.) and sometimes contain extra pictures/graphics which make them unique and appealing.

Once I got a HF rig for my apartment (a Century 21 CW-only HF rig which puts out ~30 watts, pictured below), I started making contacts and getting QSL cards myself, so I wanted to send some nice ones in return. Being a poor college student (and a graduate student at that), I was extremely cash-limited, and didn’t want to sit around for weeks while my cards were professionally printed. I wanted a fast solution. This post describes how I created amazingly cool QSL cards in a few hours, and for less than $0.25 each!

My QSL card:
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Step 1: Design the cards with PERFECT dimensions. Here’s the deal. The most cost-effective way to print nice digital images is my local Target (a store with a 1-hr photo lab which accepts JPEGs as the image source for $0.20 cents a picture), but the snag was that they only print 4” x 6”. QSL cards need to be 3.5” by 5.25”. I used Inkscape to create an image exactly 4” by 6”, and inside of it I drew a border 3.5” by 5.25”. Everything outside that border I made black. I designed my QSL card INSIDE that border, such that when the images would be printed I could trim-off the black border and have a perfect 3.5” by 5.25” QSL card.

This is how the image turned out:
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This is what the 1-hr photos looked like:
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Step 2: Print the reverse side on full-size label paper. All I needed was some framed boxes for QSL information, so I quickly sketched up the design in Inkscape and saved it in the same format as before (4” by 6”). I left a LOT of white space around the edges so it’s very forgiving down the line. I then printed the design on full-page label paper (full-sheet stickers, available at most office stores cheaply in the printer paper section), placing 4 “backs” per page.

Here’s what the adhesive paper looked like after printing:
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Step 3: Attach backings to QSL cards. This part is easy if you have a paper cutter. I purchased mine ~5yrs ago and I *LOVE* it. It’s almost as useful as my soldering iron. Seriously, so convenient. I wouldn’t dream of doing this with scissors! Anyhow, roughly cut the sticker paper into quarters:
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Next, peel and stick on the backs of cards. DONT WORRY ABOUT OVERHANG! We’ll take care of that later…
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Step 4: Trim the edges. Make sure you do this step AFTER applying the sticker. This was the secret that I wish I realized a while ago. If you trim first, sticker placement is critical and difficult. If you place the sticker BEFORE you trim, you get *PERFECT* edges every time. Way more professional…
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How nice does that look? If you did your math correctly, your new dimensions should be EXACTLY 3.5” by 5.25”. Let’s view the back…
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Perfect!!!

Step 5: fill-out information. I decided to use a metallic Sharpie to write the name of the call sign I send this to on the front of my card. How cool does that look? This is what the front/back of this card looks like after filling it out (Hi W2BFE in Maine! You’re a celebrity!).
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I hope this information helps you. If you print your own QSL cards using this (or a similar) method, let me know about it! I have to say, for ~5 / $1, these don’t look to bad. It’s especially useful if you only want to print a few cards! Good luck.
–Scott, AJ4VD

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