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Doofus-Proofing Bias Supply

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  • #16
    Thanks Chuck, I'll check it out!

    I've got lots of regular & irregular amp values on hand, mostly 5%... I think I haven't had to ordered resistors for years, and only 22k last week. I also recycle, a lot!

    I've found that for most applications, one increment up or down doesn't really make a whole heck of a lot of difference... And I've got enough small-value that I can fine tune nearly anything that doesn't require any significant power handling, which is most everything...

    Justin
    "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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    • #17
      Just rigged up as per suggestions. Packing for a trip out of town at the moment but will try out,btweak, & report next week sometime!

      Justin
      "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
      "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
      "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

      Comment


      • #18
        Hoping your trip is for pleasure or business. And that it goes smooth. See you when you get back.
        "Take two placebos, works twice as well." Enzo

        "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

        "If you're not interested in opinions and the experience of others, why even start a thread?
        You can't just expect consent." Helmholtz

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        • #19
          Thanks Chuck, it's for fun! Though it seems I'm driving straight into the remains of that hurricane in the Gulf right now! S'okay, could use an adventure too...

          Justin
          "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
          "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
          "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

          Comment


          • #20
            Hey All,

            Here's what I ended up with. Thanks for all the help! If I understand the schematic, I end up with full negative voltage (-56V) if the wiper opens? Also, if I turn the pot quickly it takes a few seconds for the voltage to ramp up or down. Is tht due to my caps being too large? I'm not too worried about it since tubes are so forgiving.,, And it's what I have that fits in the space.

            JustinClick image for larger version

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            "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
            "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
            "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

            Comment


            • #21
              Something about that drawing format just won't click with my brain, so my OCD forces me to do this.
              Yes, you will get coldest (full negative voltage) bias if the wiper goes open.



              Click image for larger version

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              Originally posted by Enzo
              I have a sign in my shop that says, "Never think up reasons not to check something."


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              • #22
                Do whatever ya gotta do! You're smarter at this than me... As long as it works the same!

                I'm still trying to figure out the whose "arrow through the squiggle line means what?" thing... I just haven't done enough of this to commit it to memory yet. I'll get there.

                Justin
                "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

                Comment

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