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Thread: Prototyping board

  1. #1
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    Prototyping board

    Is it even possible/worth building a prototyping board to prototype vacuum tube amps? I mean I'm working on a 36VCT based one to play with a certain 12AU7 design (9V battery powered distortion pedal, I have a slightly different idea in mind on the same lines), but prototyping full 600V 6L6 tubes etc etc ....

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    Old Timer defaced's Avatar
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    I do it on poplar board with copper nails for preamp circuits that sit at around 400v DC on the high end. All of the high voltage stuff is on the power tubes which with minimal effort you can do point to point.
    -Mike

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    Quote Originally Posted by defaced View Post
    I do it on poplar board with copper nails for preamp circuits that sit at around 400v DC on the high end. All of the high voltage stuff is on the power tubes which with minimal effort you can do point to point.
    Nods. I'll be playing with preamp tubes and cascading distortion at around 9-15V, hence the 12AU7.

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    Someone has recommended an LM317 type chip... I'm looking at some of these such things that can run in Switch Buck Mode, looks like they oscillate on/off against a diode and inductor (inductors are a mystery to me) to pulse i.e. 18V 50% of the time and output basically 9V, somehow (this voltage adjustment must be the inductor's doing; a capacitor would just overheat and stabilize 18V).

    36V * 1.41 == 47.16, so I'd need a 50V LM317-type chip (there's a 60V one for 60 cents) ... also a $10 V meter, maybe a digital one, next to the adjuster, and a current limiter for that.

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    A 2' x 2' plywood board with a typical power supply built-on to it with all of the PSU components on Fahnestock clips, and plenty of Fahnestock clips in a double-row arrangement works nicely.

    Some of you might need to look up "Fahnestock Clips".
    John R. Frondelli
    dBm Pro Audio Services, New York, NY

    "Mediocre is the new 'Good' "

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    Senior Member Enzo's Avatar
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    Christmas day, 1954, I met my first Fahnstock clip. I been in electronics ever since.

    Last night I typed up a detailed post and then lost it.

    But AES sells nice glass epoxy boards with tube sockets and turrets. I have a few and they are cool. They come in both octal and 9-pin versions. The 9-pin ones come in single, two, and three socket models Here is the two socket, stock P-TB9-2-2


    And some of them come with a third row of turrets if you want.

    These may be more for the prototype stage than the initial breadboarding, but I think they are cool.

    Antique Electronic Supply

    Under vacuum tube accessories - epoxy terminal boards
    Education is what you're left with after you have forgotten what you have learned.

  7. #7
    Noodle of Reality Steve Conner's Avatar
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    You need one of these
    Attached Thumbnails Attached Thumbnails toaster.jpg  
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    These are also nice.
    Attached Thumbnails Attached Thumbnails aufbauplatten_1.jpg  

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    Senior Member Enzo's Avatar
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    I think you need to route the yellow wire a little closer to the white one.
    Education is what you're left with after you have forgotten what you have learned.

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    Quote Originally Posted by Steve Conner View Post
    You need one of these
    Looks dangerous Steve. I LOVE it!!!
    John R. Frondelli
    dBm Pro Audio Services, New York, NY

    "Mediocre is the new 'Good' "

  11. #11
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    Quote Originally Posted by defaced View Post
    I do it on poplar board with copper nails for preamp circuits that sit at around 400v DC on the high end. All of the high voltage stuff is on the power tubes which with minimal effort you can do point to point.
    I do almost exactly the same thing. The minor differences are that I use 3/8" plywood, and #2 brass wood screws. No hammering is needed for screws - so I can add new screws as the circuit evolves, even with the board already populated. I use a small drill bit in a pin-vise to make a pilot hole for the screw.

    I mount the screws and components on the underside of the board, with the valves on top. That keeps heat away from the components. Also, when finished, I mount the whole thing with standoffs inside a cheap metal baking tray or cookie sheet, which provides a ground-plane and shielding.

    It works well enough that, for one-off projects, the prototype can become the finished product with no changes (other than adding a suitable housing, front panel, etc). Plywood of this thickness is very durable, and more than stiff enough to take the weight of reasonably-sized power and output transformers, and to cope with valve insertion-removal forces.

    If you don't have access to a table saw, Michaels (craft store) usually carries conveniently sized pieces of high-grade plywood that are perfect for this.

    -Gnobuddy

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