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Thread: DIY easy to build audio signal-tracer project for 2019.

  1. #1
    Overlord of Music DrNomis_44's Avatar
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    DIY easy to build audio signal-tracer project for 2019.

    Hey everyone,


    I've got a new DIY project scheduled for 2019, it is a piece of test equipment called an audio signal-tracer, the design outline is as follows:


    * Has to be relatively easy to build so that newbies to electronics can build it, but at the same time, a bit more complex than a simple audio probe.

    * Includes a stepped attenuator so that the audio signal-tracer can be used to trace signals in circuits where large signal levels are present, such as solid-state or valve guitar amplifiers, as well as DIY guitar effects pedals.

    * Includes a variable volume control.

    * Includes an internally mounted speaker.

    * At least 1W audio power output.

    * Includes an audio signal generator.

    * Battery, or mains powered via a plugpack adaptor.

    * Includes a probe with a grounding wire.

    I'll be including a write-up of how I go about building the audio signal-tracer, which will also include a complete parts list so that anyone interested can build one for themselves.


    Stay tuned for more updates....

  2. #2
    Mentor Marcel's Avatar
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    Looking at your list Doc by the time I read the last line of your post my imagination had reached at least a dozen possibility options. ..

    That said, I have never really been one for tracer probes, though there also has been times where I would have found one useful. My bench usually has a audio generator and a scope to do all my tracing work.

    I'll be interested to see what you come up with...
    Builds-
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    #14 PBG PRS-1H http://www.buildyourownguitar.com.au...ead.php?t=8021
    #13 PBG SGM-1 http://www.buildyourownguitar.com.au...ead.php?t=7771
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  3. #3
    Overlord of Music DrNomis_44's Avatar
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    Quote Originally Posted by Marcel View Post
    Looking at your list Doc by the time I read the last line of your post my imagination had reached at least a dozen possibility options. ..

    That said, I have never really been one for tracer probes, though there also has been times where I would have found one useful. My bench usually has a audio generator and a scope to do all my tracing work.

    I'll be interested to see what you come up with...

    I was thinking of basing the design on some potted modules you can buy from Jaycar Electronics, there's a few other designs I could think of too, maybe what I could do in this thread is present a few different designs that anyone interested can choose to build, feel free to offer some advice if you like mate, cheers in advance.


    This thread is mostly geared towards those who aren't able to afford a good Oscilloscope and Signal Generator, but would like something a bit more fancy than a basic audio probe.
    Last edited by DrNomis_44; 30-12-2018 at 01:33 PM.

  4. #4
    Mentor Marcel's Avatar
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    Anything that gets the job done is cool...

    Years of doing any "trade" can cause bias, and with +40 years in my trade I know I'm pretty biased up, but I also know through training young'uns a fresh mind and a new set of eyes often comes up with wonderful new ideas...
    Builds-
    #16 PBG IB-1Q http://www.buildyourownguitar.com.au...ead.php?t=8754
    #15 PBG TLA-12 http://www.buildyourownguitar.com.au...ead.php?t=8444
    #14 PBG PRS-1H http://www.buildyourownguitar.com.au...ead.php?t=8021
    #13 PBG SGM-1 http://www.buildyourownguitar.com.au...ead.php?t=7771
    #12 PBG JK-2
    #11 Scratch build AC15 clone head
    #10 PBG RCM-4F
    #09 PBG ES-1TL
    #07 partscaster Alder Denim Tele.

  5. #5
    Mentor Rabbitz's Avatar
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    Mid last year I ran into an issue when trying to interface a PC Sound card to a two-way radio for data comms. I needed to trace and measure audio but ran into a small problem:
    It turns out I have never owned an oscilloscope as the places I have worked have always had one - however that is no longer true.

    I ended up getting something similar to this from eBay:
    https://www.ebay.com.au/itm/Assemble...item4432085e2b It was about $30 assembled and delivered. A build it yourself version is available for less.

    It might be a nice, relatively cheap option to add to the project.
    Col.

    I admit that I am an agent of Satan, however, my duties are largely ceremonial.

    \m/

  6. #6
    Mentor JohnH's Avatar
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    Quote Originally Posted by Rabbitz View Post
    Mid last year I ran into an issue when trying to interface a PC Sound card to a two-way radio for data comms. I needed to trace and measure audio but ran into a small problem:
    It turns out I have never owned an oscilloscope as the places I have worked have always had one - however that is no longer true.

    I ended up getting something similar to this from eBay:
    https://www.ebay.com.au/itm/Assemble...item4432085e2b It was about $30 assembled and delivered. A build it yourself version is available for less.

    It might be a nice, relatively cheap option to add to the project.
    You've reminded me that I've been meaning to build one of these for ages. It's so cheap - I think I might just order one now...
    #001 (LP-1S) [finished - co-runner up Nov 2018 GOTM]
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  7. #7
    Mentor Rabbitz's Avatar
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    Yes cheap as chips...

    I did forget to mention that it has a 1 kHz (at 3.3 v) signal source built in.
    Col.

    I admit that I am an agent of Satan, however, my duties are largely ceremonial.

    \m/

  8. #8
    Hi...for a simple staircase waveform generator, I used half of a four-bit binary counter IC (HC393?) to get up to sixteen steps, with a passive resistor ladder on the outputs (but into an opamp buffer amplifier) to do the digital-to-analog conversion. I put that through a step attenuator and then a small power amplifier. A chipamp (e.g. LM1875, LM3875 or larger) might work well for the power amplifier, although I used an opamp with a BC139/BC140 push-pull booster amp inside the feedback loop, since I didn't need too much power. I configured the small power amplifier as a Howland-type voltage-controlled current source, but could switch in a power-resistor load to make it into a voltage source. That way I could get either calibrated current steps or calibrated voltage steps. I also had an inverting opamp amplifier that could be switched in, before the power amp. That way I could get either polarity for the staircase.

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