• This topic has 18 replies, 4 voices, and was last updated 1 week, 1 day ago by bodger.
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    • #8599
      bodger
      Participant

      I had seen a transistor flip-flop in the Lectron documentation, but not a vacuum tube one.  First, I built a vacuum tube astable multivibrator (an oscillator, also known as an Abraham-Bloch circuit) using an ECC81 dual triode.  It was fairly easy to get working.  Then I decided to move on to a bistable multivibrator (a flip-flop, also known as an Eccles-Jordan circuit).  This was a lot trickier, but I did get it working.  In the process, I found a fairly compact arrangement, too.

    • #8609
      mwpeters75
      Keymaster

      Hi Bodger,

      Thank you so much for this contribution!  It is great that someone appreciates the legacy vacuum tube technology and can add to the instruction manual with new innovations.  Wonderful!  I look forward to more of your experiments.

      What is the value of the resistor that you have in the steck block?  I cannot read the color bands.

      What would a real world application be for the circuit that you have presented?

      Best regards,
      Michael

      • This reply was modified 1 month ago by mwpeters75.
      • This reply was modified 1 month ago by mwpeters75.
      • This reply was modified 1 month ago by mwpeters75.
    • #8613
      bodger
      Participant

      The resistor is 18Ω:  the output from the power supply block is a bit much for a single tube, so I copied the approach in other Lectron single-tube builds and used the series resistor.

      The original vacuum tube computers and many other devices (like clocks, frequency counters, and the like) used this sort of circuit as either a memory cell or a counter stage.

      • #8614
        mwpeters75
        Keymaster

        Thanks Bodger!  You, Frank and Günther are a veritable treasure trove of information and knowledge.  I am very grateful that you all are making such excellent and valuable contributions for the benefit of our fellow Lectroneers.

        Thank you 🙂 ,
        Michael

        • This reply was modified 1 month ago by mwpeters75.
    • #8616
      Guenni75
      Moderator

      As a complement to post 3 I like to add a sample of a typical plug-in unit used in commercial computers since ~ 1949 until the 1960ies (the transistorized IBM 1401 was introduced in 1959):

      Best,

      G.

      • #8623
        mwpeters75
        Keymaster

        Nice advertisement Günther!

        Here’s one that is not as old (1967) for our beloved Lectron System here in the US.

    • #8618
      LectronFan
      Moderator

      Now, that’s a great showcase of “old” technology in a contemporary environment !

      Can you also design a monostable circuit ?

      The setup is very compact indeed, a good example of a nice design.

      A question, do you need to adjust the 250K potentiometers ?

      And for what reason ?

      Greetings

    • #8620
      bodger
      Participant

      I haven’t yet attempted a monostable circuit.  I was thinking of seeing if I could upgrade it from a “set/reset” flip-flop to a “toggle” flip-flop so I could use it as a counter (thinking of using the EAA91 dual diode block as a steering diode).  I was using the potentiometers to find the ratio that would flip and maintain states reliably, I’m hoping to replace them with discrete resistors to make it easier for others to build.

    • #8621
      LectronFan
      Moderator

      A true challenge then !

      I also proposed several circuits around toggle flip flops here on the forum build with the new NPN and the legacy PNP transistors. Both differ quite a lot and demand different component values.

      Great circuits and fun to use, have you checked them out ?

      I hope you continue to contribute here on the forum, the more the merrier !

      Which Lectron sets do you have ?
      Many greetings

      • #8622
        mwpeters75
        Keymaster

        Hi Frank,

        Excellent question about what Lectron System models our new Lectroneer has!  I was very pleasantly surprised to see that he had a vacuum tube model of which there are several.  Nice to see vacuum tube tech simulating digital circuits!

        • This reply was modified 1 month ago by mwpeters75.
    • #8625
      bodger
      Participant

      I originally had a Series 1 set that I received as a gift in the 1970s, along with a Series 3 set I received a few years later.  I since bought a Series 2, the Elektronik AG set (1103), the Radiotechnik set (1110), and the Ausbau-System Radio-Röhrentechnik set (1120).  I would very much like to aquire more sets, but as far as I can tell, delivery is only available to Germany these days.

      I did build the semiconductor based (NPN and PNP) flip-flop circuits from the manuals, which is where I got the idea of re-implementing them with vacuum tubes.

      I’m also considering building a ferrite core memory like the ones in Günther’s amazingly complete listing, which are presumably not obtainable.

      I did reimplement the bistable one with fixed resistors instead of potentiometers, it works well.  I have the “toggle” version just barely working, but it’s not reliable yet:  higher value resistors or capacitors would help, but all of the higher value capacitors I have are low voltage units (I may try a couple of steck blocks to substitute others), and the only resistor I have that’s more than 100kΩ is a single 2.2MΩ unit.

      • #8626
        mwpeters75
        Keymaster

        Hi Bodger,

        Thanks very much for your historical accounting of your Lectron System involvement and acquisitions.

        Purchasing Lectron System models from Lectron, GmbH seems to be a dicey proposition right now.  It does not seem that Mr. Pohl wants to continue with the Lectron System.  There are certainly enough parts on hand to continue with putting models together having visited the ‘store’ last year.

        The virus situation has not helped either and I know that Mr. Pohl scaled down the employees allocated to the Lectron System fulfillment process.  I had hoped to visit Germany sometime in 2020 but now those plans are not certain.

        If you need particular legacy blocks, please let me know and perhaps I have what you need and can send them to you at no cost to you.

        Where do you live in the US?

        Best regards,
        Michael

        • This reply was modified 1 month ago by mwpeters75.
    • #8628
      bodger
      Participant

      Goodness, that’s thoughtful of you!  In particular, I’m looking for two of the 2303 0.47µF 250V HV capacitors, two of the 2230 470 kΩ, and another of the 2215 2.2 MΩ resistors.  Also useful would be two of the 2402/2405 silicon/HV diodes, the 2130 “doppelwinkel” connector block, another couple of the steck blocks for arbitrary components, or some of the empty blocks I could use to assemble my own.  I live on the east coast of the US, in Virginia, not too far from Baltimore, MD and Washington, DC.

      • #8632
        mwpeters75
        Keymaster

        Hello Bodger,

        I will check my inventory during the coming week and let you know what I find.  Always glad to help and encourage a fellow Lectroneer!

        You are not too far away from me – I live in Pocono Pines, PA.  If you are ever in the Poconos, please let me know.  I think that you would enjoy seeing my Lectron System museum 🙂 .

        Best,
        M.

        • This reply was modified 1 month ago by mwpeters75.
      • #8648
        mwpeters75
        Keymaster

        Hi Bodger,

        Here are the blocks I can offer you.  Sorry for the omission of the others.  Please send me your mailing address by using the Contact the Curator email form in the yellow box on the right.

        Thanks,
        Michael

        • This reply was modified 3 weeks, 2 days ago by mwpeters75.
        • #8683
          mwpeters75
          Keymaster

          Hi Bodger,

          I mailed out these parts to you on Friday.  Please advise upon receipt.  The USPS is not always the most reliable service!

          Best,
          Michael

          • #8737
            bodger
            Participant

            The parts arrived today, thank you!  These should be a big help for the higher voltage, higher impedance vacuum tube circuits.

            Best,

            John

    • #8630
      bodger
      Participant

      Here’s the bistable one with fixed resistors.

      • #8634
        mwpeters75
        Keymaster

        Nice work Bodger!

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