The personal website of Scott W Harden

Puxing 777 Radio Headset Schematic

I successfully created a speaker/microphone/transmit button circuit for the puxing 777 which probably works for all puxing radios. Instead of simply using circuits found on other websites (always for other radios), I decided to reverse-engineering an earphone/microphone headset that came with the radio to determine how it worked. I can't claim that I'm an expert in electronics theory, but I can say that I faithfully rebuilt the circuitry within the factory-shipped headset and it worked. The result allows me to leave my handheld radio in its charger while casually listening/transmitting with a button that I made instead of having to reach around and awkwardly squeeze the transmit button on the side of the radio. Once again, I built this circuit and it was successful for me, but there may still be a better way to do it.

The microphone is a 20-cent electret microphone with no special modifications. The speaker I used is a standard 8ohm loudspeaker with no special modifications. The switch is a keyboard-style (push-to-talk) switch, and the capacitor I used is good for 10nF.

If you have any ideas for improvements, let me know! I'll post some photos once I have my completed little "base station" set up. My ultimate goal is to turn an el-cheapo handheld VHF radio into a decent desktop transceiver by combining it with a nice antenna (located on a balcony at 30ft) and a convenient, easy-to-use switches/buttons/microphone/speaker/etc on a desktop panel.

Markdown source code last modified on January 18th, 2021
---
title: Puxing 777 Radio Headset Schematic
date: 2009-04-22 11:56:42
tags: amateur radio, circuit, old
---

# Puxing 777 Radio Headset Schematic

__I successfully created a speaker/microphone/transmit button circuit for the puxing 777__ which probably works for all puxing radios.  Instead of simply using circuits found on other websites (always for other radios), I decided to reverse-engineering an earphone/microphone headset that came with the radio to determine how it worked. I can't claim that I'm an expert in electronics theory, but I can say that I faithfully rebuilt the circuitry within the factory-shipped headset and it worked.  The result allows me to leave my handheld radio in its charger while casually listening/transmitting with a button that I made instead of having to reach around and awkwardly squeeze the transmit button on the side of the radio.  Once again, I built this circuit and it was successful for me, but there may still be a better way to do it.

<div class="text-center img-border">

[![](puxing_thumb.jpg)](puxing.png)

</div>

The microphone is a 20-cent [electret microphone](http://en.wikipedia.org/wiki/Electret_microphone) with no special modifications.  The speaker I used is a [standard 8ohm loudspeaker](http://en.wikipedia.org/wiki/File:3.5_Inch_Speaker.jpg) with no special modifications.  The switch is a keyboard-style (push-to-talk) switch, and the capacitor I used is good for 10nF.

<div class="text-center img-border">

![](headset.jpg)

</div>

__If you have any ideas for improvements, let me know!__  I'll post some photos once I have my completed little "base station" set up.  My ultimate goal is to turn an el-cheapo handheld VHF radio into a decent desktop transceiver by combining it with a nice antenna (located on a balcony at 30ft) and a convenient, easy-to-use switches/buttons/microphone/speaker/etc on a desktop panel.

Code Practice Oscillator and Keyer

Over the last couple weeks whenever I had the time I'd work on creating a little Morse code keyer. After a few different designs I came up with the winner. 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 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 fun doing it. Now I guess I should put more time into learning Morse code...

Thoughts from future Scott (August 2019, ten years later)

Wow this is rough! I'm 90% sure this is based on a 555 circuit. lol @ the use of Jenga blocks. It looks like the wire was sourced from cat5 cable. That aluminum slab later became the base and heat sink for an IRF510-based push-pull amplifier.

Markdown source code last modified on January 18th, 2021
---
title: Code Practice Oscillator and Keyer
date: 2009-04-20 14:20:00
---

# Code Practice Oscillator and Keyer

__Over the last couple weeks whenever I had the time__ I'd work on creating a little Morse code keyer. After a few different designs I came up with the winner. 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 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 fun doing it. Now I guess I should put more time into learning Morse code...

<div class="text-center img-border">

[![](img_1535-500x375.jpg)](img_1535.jpg)
[![](img_1537-500x375.jpg)](img_1537.jpg)
[![](img_1538-500x375.jpg)](img_1538.jpg)

</div>

<blockquote class="wp-block-quote"><p><strong>Thoughts from future Scott (August 2019, ten years later)</strong></p><p>Wow this is rough! I'm 90% sure this is based on a 555 circuit. lol @ the use of Jenga blocks. It looks like the wire was sourced from cat5 cable. That aluminum slab later became the base and heat sink for an IRF510-based push-pull amplifier.</p></blockquote>

Scott is now Licensed! (KJ4LDF)

I've taken the plunge into the geek world by becoming a licensed amateur radio operator. My wife and I both took our technician exam last week, and this morning I discovered that our call signs have been processed. I'm KJ4LDF, she's KJ4LDG. I'm a little disappointed that my call sign has an "F" in it. On the air, "F" and "S" sound similar, so I'm more likely to have people asking me to repeat it. The phonetics are Kilo, Juliet, Four, Lima, Delta, Foxtrot. Foxtrot! How silly is that? [sighs] Either way, I'm glad I've been added to the database, and am now legally able to begin broadcasting on VHF/UHF.

Beacon stuff (like I wrote about in the last post) would best involve lower frequencies, which would mean I have to take another exam to get a higher license class.

Markdown source code last modified on January 18th, 2021
---
title: Scott is now Licensed! (KJ4LDF)
date: 2009-04-15 08:56:37
tags: amateur radio, qrss
---

# Scott is now Licensed! (KJ4LDF)

<div class="text-center img-border">

![](qrss.jpg)

</div>

__I've taken the plunge__ into the geek world by becoming a licensed amateur radio operator. My wife and I both took our technician exam last week, and this morning I discovered that our call signs have been processed. I'm KJ4LDF, she's KJ4LDG. I'm a little disappointed that my call sign has an "F" in it. On the air, "F" and "S" sound similar, so I'm more likely to have people asking me to repeat it. The phonetics are Kilo, Juliet, Four, Lima, Delta, Foxtrot. Foxtrot! How silly is that? [sighs] Either way, I'm glad I've been added to the database, and am now legally able to begin broadcasting on VHF/UHF.

<div class="text-center img-border">

[![](radiospec_thumb.jpg)](radiospec.png)

</div>

Beacon stuff (like I wrote about in the last post) would best involve lower frequencies, which would mean I have to take another exam to get a higher license class.
April 14th, 2009

Pointless Beacon Idea

I got an idea today for an odd but interesting project. The idea is still in the earliest stages of development, and I further research the idea (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 a microcontroller. What data will it 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 or something. Who cares - it'd be fun to make regardless of what it transmits. I could put it all 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 like to 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.

My idea is to keep construction costs to a minimum because I'm throwing this away as soon as I make it. My goal is to make it work so I can toss it in some random location and see how long it will run. Days? Weeks? Months? Years? How cool would it be to go to dental school, come back ~5 years from now, and have that transmitter still transmitting data. I've been poking around and I found someone who did something similar. They built a 40mW 10m picaxe-powered beacon using a canned oscillator as the transmit element.

I understand the basics of radio, amplitude and frequency modulation (AM and FM), etc., but I've never actually built anything that transmits radio waves. I could build a SoftRock radio, 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.

Markdown source code last modified on January 18th, 2021
---
title: Pointless Beacon Idea
date: 2009-04-14 12:39:20
---

# Pointless Beacon Idea

__I got an idea today for an odd but interesting project.__ The idea is still in the earliest stages of development, and I further research the idea (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 a microcontroller. What data will it 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 or something. Who cares - it'd be fun to make regardless of what it transmits. I could put it all into a drybox (pictured).

<div class="text-center">

![](waterproof_box1.jpg)
![](waterproof_box2.jpg)

</div>

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 like to 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.

<div class="text-center img-border">

[![](beacon_thumb.jpg)](beacon.jpg)

</div>

__My idea is to keep construction costs to a minimum because I'm throwing this away as soon as I make it.__ My goal is to make it work so I can toss it in some random location and see how long it will run. Days? Weeks? Months? Years? How cool would it be to go to dental school, come back ~5 years from now, and have that transmitter still transmitting data. I've been poking around and I found someone who did something similar. They built a 40mW 10m picaxe-powered beacon using a canned oscillator as the transmit element.

<div class="text-center">

[![](beacon2_thumb.jpg)](beacon2.jpg)

</div>

I understand the basics of radio, amplitude and frequency modulation (AM and FM), etc., but I've never actually _built_ anything that transmits radio waves. I could build a [SoftRock](http://www.softrockradio.org/) radio, 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.

April 9th, 2009

I was poking around the internet looking at various ways people made smooth-fading LED circuits and I came across the site of a guy who did something pretty creative that made me smile. Before I got too far, I wanted to mention that I saw a ton of plans involving fading LED intensity utilizing 555 timer ICs, but for my purposes a series capacitor before the LED should do fine. Here's the site which documents the project. Basically it's a skull with red LED eyes which glow in response to hard drive activity. The capacitor makes the eyes fade in and out smoothly, as opposed to the jerky on/off flashing of standard hard drive activity LEDs. Very clever!

Markdown source code last modified on February 16th, 2021
---
title: Custom HDD LEDs
date: 2009-04-09
tags: old
---

**I was poking around the internet looking at various ways people made smooth-fading LED circuits** and I came across the site of a guy who did something pretty creative that made me smile. Before I got too far, I wanted to mention that I saw a ton of plans involving fading LED intensity utilizing 555 timer ICs, but for my purposes a series capacitor before the LED should do fine. [Here's the site](http://metku.net/index.html?path=mods/hdd_eyez/index_eng) which documents the project. Basically it's a skull with red LED eyes which glow in response to hard drive activity. The capacitor makes the eyes fade in and out smoothly, as opposed to the jerky on/off flashing of standard hard drive activity LEDs. Very clever!

<div class="text-center img-border">

![](casemod.jpg)

</div>
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