Tube prototyping station

[Gio] enjoys using vacuum tubes in his projects. He designs the circuits using a CAD program but was finding that there is no substitute for actually building a prototype before heading to a final design. To make this process easier, he built his own tube prototyping station.

At the top of the board he’s got three different sizes of tube sockets with the pins from each wired as common. The nine pins from the sockets break out to a terminal strip where they can be interfaced with a solderless breadboard. For added versatility he’s included terminals to tap into some RCA jacks, as well as a 100 kOhm variable resistor. We’d bet this is not something that you can find ready-made, but it sure does look a whole lot better than a workbench full of components alligator-clipped together.

Comments

  1. theweirdness says:

    Thats Pretty sick!

    Great idea and it looks like it would be fun to use :D

  2. Kaj says:

    Wow, I should build one of those… sure beats soldering tag leads to the socket and plugging them into the breadboard, transistor style (like I do now…). I do worry about how much of an effect all that capacitance from the breadboard has on those hi-impedence circuits, though. It’s why I never expect it to sound exactly the same when it’s wired point-to-point. Nice hack, simple and well thought out!

  3. The Steven says:

    Ok, who’s up for building a full scale tube-tester?

  4. reboots says:

    You can find these ready-made…if you’re willing to go back far enough. I used to have a tube breadboarding kit from the ’50s which fit into a large wooden suitcase. It included a variac-adjusted power supply and several drawers of tube sockets and various discrete parts mounted on plastic carriers with metal pins for electrical connectivity. The front of the suitcase was lined with perforated pegboard; you snapped parts into the pegboard and connected the pins with jumper wires. The whole thing was so cumbersome and problematic that I only used the power supply, and eventually junked the rest. (Boo hoo!)

    It really highlights the sea change brought about by transistors; all that junk was obviated by a solderless breadboard you can fit in your pocket. Tube prototyping still requires a lot of fabrication and this guy has done a great job. A++ for literal breadboarding! I’d be concerned about the reliability of a solderless breadboard at typical plate voltages of 150-450VDC though.

    Here’s one of my own tube prototyping aids–a 6.3VAC/300VDC power supply built into some old hard drive cases.

    http://reboots.g-cipher.net/projects/theremin/image/powersupply.jpg

  5. simpleplan says:

    I still think this looks like a much better solution:
    http://www.tubelab.com/images/TL3/6AV5_amp.jpg

    See here for more photos:
    http://www.tubelab.com/The_Tubelab.htm

  6. therian says:

    please tell me there is no high voltage on breadboard

  7. sly says:

    doesn’t look like any high voltage on that setup (not all tubes required HV). I wouldn’t doubt some high current capability with that circuit though. Definitely may be pushing 70% of the breadboard’s capacity on a few lines.

  8. Kaj says:

    Re: Reboots
    I am (slightly sad) to say that I have used a modular breadboard in excess of 250VDC without incident. Of course, I never actually /trust/ it to be safe…

  9. asdf says:

    I’m sure there is high voltge over there or that big .47 uF capacitor would be at least 20 times smaller. From its size I guess it’s rated at least for 200-400 volts.
    I you never worked with tubes before and try this arrangement, be very careful with capacitors: if unloaded they can keep their charge for a long time and you can get a shock touching a board that was turned off for days.

  10. simpleplan says:

    I have routinely put 300VDC on cheap breadboads without issue. The trick is to make sure you don’t have any large voltage differences between neighboring columns. As long as you space everything out, there is really no problem. You might notice that this guy has at least 5 columns between every connection. I usually avoid using the rails, but I am not sure that matters too much.

  11. Rick Autry says:

    WOW! I Like it.I’m a I’ve got a tube habit myself,and I always end up pulling my hair out at 3 in the morning trying to balance out what should be a perfect bias (or whatever) and I find what’s on paper just doesn’t translate to(my)reality. I guess I should have built one of my own LONG ago. Thanks for the inspiration. Maybe I’ll build two, or one with sockets and transformers for pre and power amp protos. Now-To the coffee pot!

  12. asdf says:

    When I was a kid one of the electronics experimenting boxes I received had a breadboard full of holes and spring fixtures to connect the components together solderless. There were no tubes of course due to the thing being oriented to kids, but that arrangement would be very useful for tube prototyping.

  13. frank says:

    @therian, others:

    there most certainly is high voltage on that breadboard. zooming in to the photo, i see the tube is a dual triode with 9 pins, and i’ll bet dollars to donuts it’s a 12A_7 (pins 1 and 6 are the plates).

    others say they’ve had no problems with high vdc on breadboards, but i personally would not feel comfortable with such a situation. i’d also, as others said, worry about the parasitic capacitances.

    the build is nicely done though, very clean and well organized.

  14. Surely some Devry solderless breadboards from the vacuum tube era can still be found. No doubt when used sensibly this could meet the needs of many if not most.

  15. Peter says:

    Neat hack.

    I am reminded of what my old Analog Design professor said once. Something about losing fewer students in the lab when they switched over from tubes to transistors. :)

  16. Karel says:

    Those plug-in boards make for nice distributed capacitance arrays! It would be rough to proto anything of super-high impedance. However, with adequate layout considerations, it could be quite handy! Just don’t try to do anything with DC-to-daylight bandwidth. Or anything with a lot of dv/dt. FRATZ!

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