• Re: Theremin

    From Martin Ridgley@1:153/831 to Mike Ross on Thu Nov 9 06:52:06 2000
    MIKE ROSS wrote to Martin Ridgley <=-

    The basic principle of the theremin is that of beating (sum and
    difference frequencies) between two radio frequency oscillators.
    <snipped and saved>
    Hope this wasn't too long an explanation...

    Well, it probably falls under the heading of 'more information than
    I really needed to know', but I've been casually interested in the
    Theremin for some years now. I've even considered buying, or building
    one on occasion, so I found this quite fascinating.

    Thanks...

    Martin
    ~~~~~~~~

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  • From MIKE ROSS@1:167/133 to Martin Ridgley on Thu Nov 9 15:00:58 2000
    "Martin Ridgley" wrote to "Mike Ross" (09 Nov 00 14:52:06)
    --- on the topic of "Re: Theremin"

    Well, it probably falls under the heading of 'more information than
    I really needed to know', but I've been casually interested in the Theremin for some years now. I've even considered buying, or
    building one on occasion, so I found this quite fascinating.

    Thanks...


    I found a DXF of a very well designed theremin circuit but I also found
    in my archives this simple experimental circuit you can toy around with.
    Mind that it's not a very good theremin. It is basically educational in
    nature, really just to show the working principles.


    Theremin

    Circuit diagram for a Theremin : the only musical instrument in the world
    (at its time) that could be played without touching it.

    Invented in the 1920's, by Dr. Leon Theremin.

    Peter Knight p.j.knight@uk.ac.bradford


    Theremin schematic

    From the book
    '103 Simple Transistor Projects' by Tom Kneitel, pp98-99
    Published by Rider, 1964

    This schematic is based on a post to sci.electronics by jmichael@vnet.ibm.com Schematic graphic by p.j.knight@bradford.ac.uk


    All transistors are PNP

    S1
    __ Q1
    9V-- --e c-------------------------------.
    b ! !
    ! Q2 e---. \!/ Q3 e---. \!/
    ! ! ! Ant1 ! ! Ant2
    ! .---b C1 ! .---b C2 !
    ! ! ! ! ! ! !
    R1 .-. c--+++--- .-. c--+++---
    ! ! ! ! ! ! ! ! !
    ! R2 C5 C3 L1 R3 C6 C4 L2
    ! !_! !_! !_! !_!
    ! ! ! ! ! 0V-------+----+---------+-----------+---------'

    Q1 2N1097
    Q2,3 2N1264

    R1 180K
    R2-3 51K

    C1,2 200pF
    C3,4 200pF Trimmer
    C5,6 0.01uF

    L1,2 vari loopstick

    S1 SPST

    Connections to the collectors of Q2,3 are made via 5 way binding posts. Antennas are Lafayette F343 whips.
    Keep leads short. Cut shield connectors off 2N1264's. Place near AM radio Adjust 200pf cap at J1 until hissing noise, then 200pf at J2 for whistle, then back to 200pf at J2 for lowest pitch. Play with hands. Perhaps an
    ascii artist can draw from the description. Good luck.


    ... Mad at your neighbor? Buy his kid a drum!
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  • From Gary Gilmore@1:2410/400 to Mike Ross on Fri Nov 10 03:36:50 2000
    From the book
    '103 Simple Transistor Projects' by Tom Kneitel, pp98-99
    Published by Rider, 1964

    Antennas are Lafayette F343 whips.

    Ahh, that explains it. When I saw the above line, I was thinking "??!!??". Lafayette ("Lafayette Radio Electronics", actually) has been out of business since probably 1975 or possibly earlier. I used to get parts there when I was a kid, and still have a great old power amp from them which is labled "Knight",
    which is their brand name.

    Funny to see them mentioned anywhere again. Olsen Electronics was another chain that faded away about the same time, and were pretty much identical to Lafayette. (And another that I used to spend a lot of time in.)

    --gary

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  • From MIKE ROSS@1:167/133 to Gary Gilmore on Fri Nov 10 16:01:44 2000
    "Gary Gilmore" wrote to "Mike Ross" (10 Nov 00 11:36:50)
    --- on the topic of "Re: Theremin"

    Antennas are Lafayette F343 whips.

    Ahh, that explains it. When I saw the above line, I was thinking "??!!??". Lafayette ("Lafayette Radio Electronics", actually) has
    been out of business since probably 1975 or possibly earlier. I used
    to get parts there when I was a kid, and still have a great old power
    amp from them which is labled "Knight", which is their brand name.
    Funny to see them mentioned anywhere again. Olsen Electronics was
    another chain that faded away about the same time, and were pretty
    much identical to Lafayette. (And another that I used to spend a lot
    of time in.)
    --gary

    A lot of those great old stores are now gone. We had a similar one here
    in Montreal called Payette Radio Ltd. Anyways, downtown there was all this gorgeous WWII surplus radio equipment in the storefronts of the radio strip
    and the geewiz ham radio receivers with all the gizmos. Now it's mostly in these industrial area joints with $50 or $100 minimum purchases. Bummer...

    ... High Voltage Electronics: Life's a glitch, then you fry.
    --- Blue Wave/DOS v2.30
    * Origin: Juxtaposition BBS, Telnet:juxtaposition.dynip.com (1:167/133)
  • From Martin Ridgley@1:153/831 to Mike Ross on Wed Nov 15 12:01:02 2000
    MIKE ROSS wrote to Martin Ridgley <=-

    I found a DXF of a very well designed theremin circuit but I
    also found in my archives this simple experimental circuit you
    can toy around with. Mind that it's not a very good theremin.
    It is basically educational in nature, really just to show the
    working principles.

    <snipped and saved>

    Thanks Mike. I'm not very knowledgeable about electronics, but I
    might just get a decent set of plans and have a go at building one
    of these things one day. Hmmm.... come to think of it, it might
    make an interesting project for my girlfriend, who's currently
    studying to be an electrician. ;-)

    Martin
    ~~~~~~~~

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  • From Steve Kaplan@1:342/3 to Gary Gilmore on Fri Nov 17 22:42:52 2000
    Gary, any items that can't be obtained at a nearby Lafayette store can easily be found at your local Heathlit, Hallicrafters, or Allied store
    :) Hope this helps........hehehe (couldn't resist)

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  • From Steve Kaplan@1:342/3 to MIKE ROSS on Fri Nov 17 22:51:30 2000
    Oh man..I'd love to be find (an affordable) WW2 SWR :) Seems as tho the Zenith
    Transoceanics are about the nicest portable, (yet affordable) receivers out there. Of course I've also heard decent reviews about the Japan Radio receivers
    :( Anyway, I've heard decent
    things about the Wards Airline guitar amps too. Any of you have the
    odious priveldge of Playing a Lafayette Radio e;ectronics guitar thru a Heath 2x12 40 watt amp ? YEECH

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  • From Gary Gilmore@1:2410/400 to Steve Kaplan on Sat Nov 18 04:54:10 2000
    Lafayette store can easily be found at your local
    Heathlit, Hallicrafters, or Allied store

    Never went to a Hallicrafters store, but certainly have been to Allied and Heathkit stores in the past. I remember going to the Heathkit store and seeing
    the guitar amp kit, and lusting over it. It looked like a Fender Twin.

    --gary

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  • From Steve Kaplan@1:342/3 to Gary Gilmore on Sun Nov 19 00:48:18 2000
    Gary,
    I remember (years ago) going into the Heathkit stores, and wondering why a "kit" would in so many cases, cost more than the assembled product. Heathkit wasn't cheap, yet some of their "Ham" stuff was decent. I never had the interest in assembling (or the interest in trying). Lafayette, (where I got my first SW receiver...Starfire VI also had lot's of fun toys...Do you recall in the late 60's/early 70's the CB radio's they'd sell you w/o the microphone since you needed to be licensed to use one ? I wasn't yet 18, and back than CB radio's, and talkies (over 100MW) were taboo. SO of course we used to get on channel 9...and threaten "React"...hehe.

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