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  • solid state

    hi all,
    are there any good solid state md designs in public domain?
    anyone who knows my username from certain xbox forums or ham forums will know my comfort zone is solidstate and i was wondering.
    thanks aly
    p.s. by solid state i mean post valves/tubes technology but pre ic's,modern exotic semi conductors and so on.
    Last edited by sinclairuser; 06-03-2012, 05:23 PM. Reason: clarification

  • #4
    ....
    Attached Files

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    • #5
      Originally posted by sinclairuser View Post
      hi all,
      are there any good solid state md designs in public domain?
      anyone who knows my username from certain xbox forums or ham forums will know my comfort zone is solidstate and i was wondering.
      thanks aly
      p.s. by solid state i mean post valves/tubes technology but pre ic's,modern exotic semi conductors and so on.
      "Good" + solid state = TOUGH at metal detector technology! Not impossible, but very tough.
      As you see above; i tried to extract only such projects from my 5.7GB database on hard disk.
      Just a few!? I couldn't believe my eyes!!??
      Your demand is very interesting to me! Indeed!
      As old radio amateur i also do like old designs, especially old ham projects.
      The other day i bought "ancient" Lehnert HS-120 on local flea market! Shiny as new!
      Fully functional! Wow! Price was 12.5 euros!
      Same day i bought russian: Signal 304 and Sokol RP210 solid state SW and LW portable radio receivers! Also shiny and functional as new!
      ...
      BTW i am still keeping my ZX Spectrum 48 and ZX Spectrum + !!! (relating to your avatar)
      ZX48 is functional, except that foil is broken, Spectrum + is broken complete.
      Also keeping Schneider CPC 6128 with CTM664 in perfect shape!!!
      ...
      Point is: you are absolutely right when it comes about old radios, but pitty; it is not the same as with metal detectors. Old solid state radios are same good or even maybe better than most of new cheap technology nowdays. But with metal detectors is quite oposite situation.
      Cheers!


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      • #6
        Another one:
        Attached Files

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        • #7
          Most transistor-only designs are going to be either BFO or ultra-simple TR. Ivconic has given you an excellent start.

          An interesting challenge would be to design a reasonably decent discriminating VLF using only transistors, no opamps at all.

          - Carl

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          • #8
            Sinclairuser, here is the fresh one:

            http://www.geotech1.com/forums/showthread.php?t=19273

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            • #9
              solidstate

              thanks ivconic! i'm glad my question fell on to the right ears the reason i asked was i thought maybe there was a md from those times that was really good and even if it cost a small fortune then maybe today its schematic and so on would be public domain and buildable but all i found were the bfo/simple stuff thanks for your links plenty to have a go at though the last link has one hell of a component count!
              as for sinclair ive got a boxed +3 in mint condition for old times sake the funny thing is 2 years ago i threw my 48k rubber keyed model away as i could not get a keyboard membrane and now there is a company in the uk remanufacturing all the parts under licence from amstrad
              oh well ce la vie you might want to look them up membranes, keyboards, cases,z80cpus all available even the alloy plate with the keyboard legend/brand logo i think they sell on ebayuk so you could recon your speccy!
              the other funny thing is the parts are better quality than the originals
              thanks ivconic/carl/all aly

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              • #10
                Good to know! Thanks!
                I will search internet to see that.
                I simply can not toss it away, it is a LEGEND!
                Despite many drawbacks - it is irresistible!
                At least as vintage ornament at home!

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                • #11
                  When it comes to metal detectors, there are no oldies but goodies. The VLF synchronously demodulated induction balance revolutionized metal detection in the 1970's, and is the mainstay technology even today. As Carl pointed out, to design and build one without using op amps would be an interesting challenge, but (as he implied) a terrible waste of time.

                  Nowadays, PI's are popular projects, mostly because they don't require an induction balance searchcoil. IB searchcoils are simple in basic concept, but there are more ways for one not to work than the average hobbyist can imagine. If you want to do a VLF IB system, the best way to start is regard the searchcoil as a "component" that you buy. Bounty Hunter searchcoils are probably the least expensive and good enough to support a medium performance electronic design.

                  Regarding what has been said about radios, what you got 50 years ago (if you chose well) was the basics done right, but few features. Nowadays you get fancy features many of which aren't even usable, with the basics gotten wrong because engineers are overwhelmed with technological possibilities but lacking in basic radio engineering expertise. I owned radios half a century ago that I wish I could buy today, but can't.

                  --Dave J.

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                  • #12
                    Originally posted by Dave J. View Post
                    When it comes to metal detectors, there are no oldies but goodies. The VLF synchronously demodulated induction balance revolutionized metal detection in the 1970's, and is the mainstay technology even today. As Carl pointed out, to design and build one without using op amps would be an interesting challenge, but (as he implied) a terrible waste of time.

                    Nowadays, PI's are popular projects, mostly because they don't require an induction balance searchcoil. IB searchcoils are simple in basic concept, but there are more ways for one not to work than the average hobbyist can imagine. If you want to do a VLF IB system, the best way to start is regard the searchcoil as a "component" that you buy. Bounty Hunter searchcoils are probably the least expensive and good enough to support a medium performance electronic design.

                    Regarding what has been said about radios, what you got 50 years ago (if you chose well) was the basics done right, but few features. Nowadays you get fancy features many of which aren't even usable, with the basics gotten wrong because engineers are overwhelmed with technological possibilities but lacking in basic radio engineering expertise. I owned radios half a century ago that I wish I could buy today, but can't.

                    --Dave J.

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