Posts Tagged ‘Audio’

1 Volt/2 Volt Transceivers

Transceivers with a power supply of 1 and 2 Volts, how much can one achieve with that? Well, actually quite a lot according to DL2AVH, Helmut, who together with DL4ALJ, Gero, wrote two articles about that in the German QRP-Report in 2011. I am impressed by the output power, up to 200 mW with one battery cell (1.5 Volts) and 0.5 Watts with two cells.

I wrote about this in April last year where I also mentioned that the 1 Volt design from 2000 later had been corrected. Those corrections can be found in the article in QRP-Report 3/2011: “Niederspannungs-Schaltungtechnik – der 1-V- und der 2-V-transceiver” (Low voltage circuit technology – the 1 Volt and the 2 Volt transceivers). The improvements are concerned with better input filtering at 14 MHz with a quartz crystal in the front-end filter and better efficiency in the mixer and removal of an audio stage in the direct conversion receiver. This design only uses bipolar transistors and no ICs.

This is different in the newer 2 or 3 Volt transceiver for 7 MHz. Here an impressive figure of only 5 mA power consumption for the receiver is achieved. The transmitter consumes about 250 mA. Several MC1496P balanced modulator/demodulator ICs are used for the mixers in the transmitter and the superhet receiver, and for the product detector of the receiver. They seem to run quite comfortably on only 1.8 Volts as supplied by a low-droput regulator from the battery supply. The TDA7050 is used for the audio output stage. This is a low voltage audio amplifier for headphones which can operate with  a supply voltage down to 1.6 V.

The design is said to benefit from low voltage technology of mobile phones. This is the case for circuitry like that of the output stage of the transmitter which consists of a pair of BFG21W transistors. However, both of the ICs have been around for many years.

I think this was a very inspiring read, and the final comment about power consumption from the second article is interesting. They say that with two AA-batteries, the receiver will last for 285 hours, which is the same as 70 days of listening of 4 hours per day. With transmission for 10% of the time, the set of batteries will last for 4 weeks!

A Useless Machine with delay and howl

The useless machine or ultimate machine originates from Claude Shannon, the scientist who figured out how to find the channel capacity in a communications system. I bought the basic machine as a kit from Solarbotics.

But then I added a few features:

  • A delay circuit that makes it look more alive as it gives the impression of doing some thinking before it responds to the switch.
  • Sound that varies with how open the lid is and the amount of light that hits the photosensitive resistor. It was inspired by the design of the Growl and Scream Altoids of FightCube.
  • A couple of LEDs, a red one when it opens and a blue one when it closes.

The circuits were built on small pieces of veroboard and the circuit diagram can be downloaded from here. In retrospect I’m not completely happy with the sound, it could have growled and screamed even more, but then how much effort can one really justify putting into a project which is – useless – anyway?

Show Notes #085


  • “You know it’s summer in Texas, because all the truck tires shed their winter coats.”
  • This episode, an interview with David Rowe, VK5DGR.


  • Our hosts conduct a lively conversation with David Rowe, VK5DGR, from Adelaide, South Australia.
  • David is the author of Codec 2,, an open source speech codec designed for communications quality speech.
  • You can find more information about David and his project on his blog.
  • Powerpoint presentations and Youtube videos of how Codec 2 works are available on his Codec 2 blog page.
  • You can see David’s presentation of Codec2 at here.
  • David then describes the Mesh Potato project, an open hardware product designed specifically to build telephone networks without infrastructure like cell phone towers or land lines.
  • The Mesh Potato is available for purchase.

Contact Info:


  • None.

LHS Episode #085: David Rowe on Codec2

Please join us for a special episode of Linux in the Ham Shack. In Episode #085, the hosts interview a vibrant and brilliant engineer from Adelaide, South Australia, named David Rowe. He is the mastermind behind the codec2 open voice codec among several other worthy and equally brilliant open source projects. He dabbles in VoIP, hardware, Open Source advocacy, engineering, voice compression, amateur radio and other endeavors far too numerous to name. David Rowe is definitely one of the more special people occupying our planet and our interview with him is nothing short of amazing. Please tune in and have your mind blown. We look forward to the overspray.

73 de The LHS Guys

AmateurLogic.TV 33: One Jam Packed Show


George visits the studios and interviews Randy Hall, K7AGE. Tommy visits the Huntsville Hamfest. Jim builds an Audio Isolation Interface. Peter shows us the DATV QSO Party.

LHS Show Notes #062


  • Introductions, chit chat, a bit about the Dayton Hamvention, Texas Linuxfest, and the Belton hamfest.
  • LHS will be at several events this summer:
    • SouthEast LinuxFest (SELF), June 10-12 in Spartanburg, SC. (Yes, I know, by the time you hear this episode, it’s come and gone.)
    • Huntsville Hamfest August 20-21 in Huntsville, AL.
    • Ohio Linuxfest September 9-11 in Columbus, OH.
    • Stop by and say hello to Russ and Cheryl!
  • Richard may be attending the Texoma Hamarama October 21-22 in Ardmore, OK.
  • Russ tells us about the sewer failure at Dayton. Only two restrooms in Hara were working Saturday afternoon. Apparently it was fixed by Saturday evening.

Topic: PulseAudio

  • Richard’s son is trying to start his own computer repair business and recently he received a call from Misha who wanted him to fix a sound issue on her Sony Vaio, which dual-boots Windows 7 and Ubuntu 11.04. Sound worked fine in Windows, but not in Ubuntu, and she preferred using Ubuntu. After working with the machine for a while, he figured out that PulseAudio was the problem, and replacing it with ALSA fixed it.
  • While researching the problem, Richard discovered PulseAudio problems exist on more than just the Sony Vaio. He also found PulseAudio problems with Ubuntu, Fedora, Open Suse 11 or higher, Arch Linux, Zen, and Sabayon, and with both Gnome and KDE desktops.
  • Two sites in particular were helpful:
  • Russ and Richard discuss Linux audio problems, and the current state of PulseAudio, particularly with WINE. Russ notes that he’s had no sound problems under Linux Mint.
  • Russ describes various ways to troubleshoot PulseAudio issues on Linux.
  • In Gnome, right-click on the speaker icon and select sound preferences. From here you can examine the hardware, choose a sound profile, configure your inputs and outputs, and see which applications are using PulseAudio.
  • There are a variety of utilities useful for debugging PulseAudio problems:
    • paman (PulseAudio Manager Utility). Install it with the command “apt-get install paman”. It tells you a lot of information about PulseAudio, including “sinks” and “sources”. You can also use it to set volume levels with greater control than with the desktop audio manager.
    • paprefs (PulseAudio Preferences Panel) Install it with the command “apt-get install paprefs”. Allows you to perform advanced functions such as connecting PulseAudio servers together, send sound from one server to another, create virtual sound devices, etc.
    • pavucontrol (PulseAudio Volume Control) Install it with the command “apt-get install pavucontrol”. Allows you to see every application that accesses PulseAudio, set volume levels per channel, and other configuration settings.
    • pavumeter (PulseAudio VU Meter) Install it with the command “apt-get install pavumeter”. Creates a VU Meter window that displays your audio levels.
    • padsp, pamon Install with the command “apt-get install pulseaudio-utils”. pamon will allow you to capture the bytes of audio data. padsp allows you to pipe the audio from an application that does not normally support PulseAudio, into PulseAudio.
    • Remember, you can use the “man” command for help on any of these commands. For example, in a terminal type “man padsp” for help on the padsp utility.
  • Check out Ted’s sound card programs for ham radio. They are all now PulseAudio compatible.

Contact Info:

LHS Episode #052: Amateur Fantasies

Hello, podcast listeners! It has been an extra week that you've had to wait for our landmark episode 50 to be released. I (Russ)  had planned to do an episode from his hotel room in San Jose. Unfortunately, the network there was so bad it was impossible to record so everything was pushed back.

In this episode, we talk about life, love and amateur radio. OK, not really. But we touch on a number of interesting topics including the necessity of logging in amateur radio, theoretical nonsense like Internet via Moonbounce and, thanks to a couple of missives from AD7MI, we wax philosophical on our ideal ham shacks--computers running Linux included of course.

Thank you for being a listener of our show. If you're new: Welcome! Please tell everyone you know where they can find us. And keep fighting the good fight.

73 de The LHS Guys

Subscribe FREE to's
Amateur Radio Newsletter

We never share your e-mail address.

Do you like to write?
Interesting project to share?
Helpful tips and ideas for other hams?

Submit an article and we will review it for publication on!

Have a ham radio product or service?
Consider advertising on our site.

Are you a reporter covering ham radio?
Find ham radio experts for your story.

How to Set Up a Ham Radio Blog
Get started in less than 15 minutes!

  • Matt W1MST, Managing Editor

Sign up for our free
Amateur Radio Newsletter

Enter your e-mail address: