Analog Circuit (guitar effects)

Discussion in 'The Projects Forum' started by rfpd, Jul 6, 2016.

  1. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    Hey there, I'm new here and I have some questions about this topic, hope they are not stupid as I hope to design some effects. I'll just sum them into topics to be easier to read.

    -To be able to make distortion, we'll need to clip the top of the wave using a diode or saturating an ampop, by using diode voltage over 0.7 V would be clipped right? But how do I know how much voltage comes from the guitar?
    -I was trying to test BBD delay in multisim but I couldn't find it there unfortunately, I noticed it only allows delays up to 50ms but I would need something like 250, and I know analog delay pedals all use a BBD, so they use 5 BBDs?
    -I don't get some things about transistors, how would someone create distortion out of a transistor isn't it like a switch? The only thing I can do with it, is cutting off the negative part of the wave, I don't understand how I would make a circuit to saturate the signal.
    -I also know Proco RAT uses ampop saturation to create distortion and the uses de the diodes, what's the difference? Is it that ampop saturates too much and creates a rect signal with an unpleasing sound?

    Sorry if the questions are stupid or out of topic, thanks for your time!
     
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
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  3. rfpd

    Thread Starter New Member

    Jul 6, 2016
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  4. DGElder

    Member

    Apr 3, 2016
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    You need to study electronics before you attempt to design your own projects. You don't jump into a project and then start asking questions like how does a transistor work. You have to learn to crawl before you can walk, and walk before you can run. Get some textbooks and start there or you might start with the tutorials at this site.
     
  5. Papabravo

    Expert

    Feb 24, 2006
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    Couple of things:
    1. ampop ⇒ opamp, which is short for operational amplifier.
    2. A transistor can be used as either an amplifier or a switch. The difference is how they are biased and driven.
    3. To know how much voltage comes from a device you measure it with an instrument like a voltmeter or an oscilloscope.
    4. I'm not sure BBD devices are even made anymore, they are a very old technology. I get no hits on digikey.com, and they have everything that can be had.
    5. Saturation occurs when you overdrive the input of an amplifier, or turn up the gain with an input that would not otherwise saturate the device.
     
  6. Bordodynov

    Active Member

    May 20, 2015
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    A great help in the development schemes may have LTspice. This program can create an audio file that you can listen to. Those. on the electronic circuit can be fed the audio file and turn off the sound file at the output of the electronic circuit (Wav-format). In various forums, you can find the audio input files.
    Many of the old scheme used germanium transistors and diodes. A large collection of models (including germanium transistors and diodes) can be found on the website Ltwiki.org.
    http://ltwiki.org/index.php5?title=Components_Library_and_Circuits
    An LTspice Standard Library Replacement
    In my collection you will find all the popular transistors.

    Good groups https://groups.yahoo.com/neo/groups/LTspice/info
     
  7. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    I know eletronics, I'm in college, I know how a transistor works but I'm not a pro, I had two disciplines about this.
     
  8. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    I'm portuguese that's why I wrote ampop sorry about that ahah, didn't think about point 3, stupid question I made there. About point 5 I'm aware of how to saturate an opamp, I just don't know how to saturate a transistor (I meant making a circuit to saturate a transistor). I need a BBD to create an analog delay, digital effects don't sound as good as analog that's why I need a BBD.
     
  9. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    Thank you I'll try that soon!
     
  10. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    I think I'm getting misunderstood, I know two ways of creating saturation by using diodes, and saturating an opamp (ampop in portuguese), but I saw a fuzz circuit that uses a transistor, and I know that a transitor has 3 regions, cut off, active, and saturation, I can only "play" with cut off and active therefore I can only make like a switch for positive/negative voltage, I am asking how to induce saturation in a transistor (I know how the rest works). The only way I found to get a ms delay in a signal is using a BBD (the only analog way), for guitar effects digital is not the way to go for me, just sounds a lot worse comparing to analog. And my final question is, is there a better way to saturate? Diode clipping, ampop, transistor, what does sound better? Thank you for the answers so far.
     
  11. Veracohr

    Well-Known Member

    Jan 3, 2011
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    Transistor distortion circuits generally use them as amplifiers, so it's the same concept as saturating an opamp, it just distorts differently.

    BBD devices are still made by a company called Coolaudio, at least. They make some with longer delays, or you can cascade multiple shorter delay units.
     
    absf likes this.
  12. Papabravo

    Expert

    Feb 24, 2006
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    A transistor amp is saturated in exactly the same way as an opamp. Overdrive the input and the transistor goes outside it's linear range, or raise the gain sufficiently, that a signal of any specified level will drive the amplifier out of it's linear range. From a high level view, there is no difference in the AC operation of an opamp and a transistor amplifier. I understand your need for the BBD device -- I'm just saying that it is quite probable that you cannot obtain one at any price. Why -- because nobody makes them any more.
     
  13. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    Thanks I understand now how to make it!
     
  14. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Howdy:
    A guitar pickup usually only puts out a millivolt or two. So you want to have all kinds of amplification before you even think of clipping. (This also improves the signal-to-noise ratio) The best bet is to start out with 50 dB of gain before any effects.
     
  15. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    The delay time of the BBD is inversely proportional to the clock speed. You can get a lot longer delays by slowing the clock down...with some increase of distortion. I'd see what you can do with just one BBD, as cascading a bunch of them can get real tricky to stabilize
     
  16. Veracohr

    Well-Known Member

    Jan 3, 2011
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    The humbuckers on my guitar can peak at over 1V with a big, low pitched chord.
     
  17. absf

    Senior Member

    Dec 29, 2010
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  18. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    Thank you all for the answers, BBD doesn't get enought delay but PT2399 looks like it would do the work thanks!
     
  19. rfpd

    Thread Starter New Member

    Jul 6, 2016
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    There's only one problem it's digital, I guess there's no way for making an analog delay anymore
     
  20. Veracohr

    Well-Known Member

    Jan 3, 2011
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