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  • #16






    Quote Originally Posted by amp_surgeon
    View Post

    Either develop a passion for breadboards or use a simulator. A good sim will teach you an awful lot about how changes affect your circuit. You can use the simulator on circuitlab.com for free, and you don't have to download anything because it runs in your web browser. The downside is that it's all java script so it's really slow to run a simulation. I tried simulating only the octave amp of an FY-6 on circuitlab and it took more than an hour to generate 1000 sample points.



    There are lots of free Spice simulation engines but few with graphical interfaces. Writing simulation scripts manually isn't my idea of a pleasant afternoon, but I've done it before.



    I'm currently using 5Spice (5spice.com). The free demo version is very limited - very small schematic drawing space, and some of the simulation features are disabled, but it will give you an idea how it works. Once you register it (around $200) then it unlocks all the features, and you can draw very large schematics to simulate. I can simulate the entire six transistor FY-6 circuit and collect 10,000 sample points in a little over a second. It's very accurate, too. The waveforms I saw in simulation were exactly what I saw on the bench with the breadboard and o-scope.



    You'll need Spice models for every component you use in your circuit. 5Spice comes with some common components, and many more can be found on the internet. They're just text files containing a description of how the component performs, but they contain parameters you often won't find on a manufacturer's datasheet. For semiconductors, you can usually find Spice models on the manufacturer's website.




    Thanks dude! I was actually playing around with CircuitLab this morning. Its currently trying to generate the output waveform, should be another 20 minutes



    Im gonna grab the free version of 5Spice.
    Guitars:Gibson Les Paul Standard FadedFender Roadworn '72 Deluxe TelecasterKramer StrikerAmplification:Titan Custom RetrofitRandall R412CSOfficial member of the Ninja Lows club

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    • #17






      Quote Originally Posted by amp_surgeon
      View Post

      Either develop a passion for breadboards or use a simulator. A good sim will teach you an awful lot about how changes affect your circuit. You can use the simulator on circuitlab.com for free, and you don't have to download anything because it runs in your web browser. The downside is that it's all java script so it's really slow to run a simulation. I tried simulating only the octave amp of an FY-6 on circuitlab and it took more than an hour to generate 1000 sample points.



      There are lots of free Spice simulation engines but few with graphical interfaces. Writing simulation scripts manually isn't my idea of a pleasant afternoon, but I've done it before.



      I'm currently using 5Spice (5spice.com). The free demo version is very limited - very small schematic drawing space, and some of the simulation features are disabled, but it will give you an idea how it works. Once you register it (around $200) then it unlocks all the features, and you can draw very large schematics to simulate. I can simulate the entire six transistor FY-6 circuit and collect 10,000 sample points in a little over a second. It's very accurate, too. The waveforms I saw in simulation were exactly what I saw on the bench with the breadboard and o-scope.



      You'll need Spice models for every component you use in your circuit. 5Spice comes with some common components, and many more can be found on the internet. They're just text files containing a description of how the component performs, but they contain parameters you often won't find on a manufacturer's datasheet. For semiconductors, you can usually find Spice models on the manufacturer's website.




      Thanks dude! I was actually playing around with CircuitLab this morning. Its currently trying to generate the output waveform, should be another 20 minutes



      Im gonna grab the free version of 5Spice.
      Guitars:Gibson Les Paul Standard FadedFender Roadworn '72 Deluxe TelecasterKramer StrikerAmplification:Titan Custom RetrofitRandall R412CSOfficial member of the Ninja Lows club

      Comment


      • #18
        So I spent the day tweaking the circuit in CircuitLab. Heres what I have:















        What do y'all think? Theres a significant drop in output, but that's to be expected when you're cutting out a huge range of frequencies.
        Guitars:Gibson Les Paul Standard FadedFender Roadworn '72 Deluxe TelecasterKramer StrikerAmplification:Titan Custom RetrofitRandall R412CSOfficial member of the Ninja Lows club

        Comment


        • #19
          So I spent the day tweaking the circuit in CircuitLab. Heres what I have:















          What do y'all think? Theres a significant drop in output, but that's to be expected when you're cutting out a huge range of frequencies.
          Guitars:Gibson Les Paul Standard FadedFender Roadworn '72 Deluxe TelecasterKramer StrikerAmplification:Titan Custom RetrofitRandall R412CSOfficial member of the Ninja Lows club

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          • #20
            You may want to include coupling capacitors between the clipping circuit and restoration amplifier.
            Logic. And cats. And logical cats.Mr. Black Pedals

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            • #21
              You may want to include coupling capacitors between the clipping circuit and restoration amplifier.
              Logic. And cats. And logical cats.Mr. Black Pedals

              Comment


              • #22






                Quote Originally Posted by ej
                View Post

                So I spent the day tweaking the circuit in CircuitLab. Heres what I have:















                What do y'all think? Theres a significant drop in output, but that's to be expected when you're cutting out a huge range of frequencies.




                Where is R25 set? I seem to recall the default is 50%. Also, with emitter resistors that small you're going to be clipping in both transistor stages even with a pretty low level signal. Did you mean for this to clip in the transistor stages, or were you looking for the diodes to do the clipping?



                And seriously, 2Vpp is a pretty hot input, and 1kHz is pretty high frequency. Try it at 500mV and 100Hz or 500Hz.
                Owner/Engineer, Wattson Classic Electronics

                Comment


                • #23






                  Quote Originally Posted by ej
                  View Post

                  So I spent the day tweaking the circuit in CircuitLab. Heres what I have:















                  What do y'all think? Theres a significant drop in output, but that's to be expected when you're cutting out a huge range of frequencies.




                  Where is R25 set? I seem to recall the default is 50%. Also, with emitter resistors that small you're going to be clipping in both transistor stages even with a pretty low level signal. Did you mean for this to clip in the transistor stages, or were you looking for the diodes to do the clipping?



                  And seriously, 2Vpp is a pretty hot input, and 1kHz is pretty high frequency. Try it at 500mV and 100Hz or 500Hz.
                  Owner/Engineer, Wattson Classic Electronics

                  Comment


                  • #24






                    Quote Originally Posted by ej
                    View Post



                    What do y'all think? Theres a significant drop in output, but that's to be expected when you're cutting out a huge range of frequencies.




                    I think someone already recommended a make-up gain stage to compensate for this. IMHO, it would be a good idea if you're going to use a fairly drastic bandpass filter on the signal.
                    **********

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                    • #25






                      Quote Originally Posted by ej
                      View Post

                      So I spent the day tweaking the circuit in CircuitLab. Heres what I have:







                      [...]



                      What do y'all think? Theres a significant drop in output, but that's to be expected when you're cutting out a huge range of frequencies.




                      First of all this thread is cool, because of subject. But this has got problems. Also you're overdriving it hugely with that input level.



                      The lack of a coupling cap distorts out D1 and D2 from Q4's bias.

                      The bias on both stages is probably almost cutoff. Look at the collector voltages.

                      If R25 is 100K etc. then in needs to be after the network. This would also eliminate C14, except reuse it on the first item.
                      --------------------------------------------------------------
                      www.spenceramps.com

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                      • #26






                        Quote Originally Posted by spentron
                        View Post

                        First of all this thread is cool, because of subject. But this has got problems. Also you're overdriving it hugely with that input level.



                        The lack of a coupling cap distorts out D1 and D2 from Q4's bias.

                        The bias on both stages is probably almost cutoff. Look at the collector voltages.

                        If R25 is 100K etc. then in needs to be after the network. This would also eliminate C14, except reuse it on the first item.




                        So I actually think I fixed some of the issues you pointed out when I was playing with it more on saturday.







                        What do you think? I'm really eager to learn more about this stuff, all I have is basic working knowledge of electronics so if you wouldn't mind explaining in more detail I would appreciate it.
                        Guitars:Gibson Les Paul Standard FadedFender Roadworn '72 Deluxe TelecasterKramer StrikerAmplification:Titan Custom RetrofitRandall R412CSOfficial member of the Ninja Lows club

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                        • #27
                          That helps some but you still have a loading issue with the low-fi filter. Without running any sims or anything it is clear the impedance/resistance scale (3K load) of the filter is too low for your amplifiers (47K or 15K source). It might be better to add a buffer for the second stage that can drive that thing, another possibility is rescaling the filter and then using a buffer or higher-impedance amp to avoid loss at its output. Or drop the filter awhile.



                          You're doing pretty good and there are limits to how much I can(will) help ... you need to look at the signals at many points in the circuit if you're not doing so already, not just the output. And eventually build one and see how it sounds.
                          --------------------------------------------------------------
                          www.spenceramps.com

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