Chaos Computer Club 1997 February/cccd_beta_feb_97.iso/chaos/habi1/txt/hb1_253.txt

Text File | 1997-02-28 | 7KB | 224 lines

    ?.R 1 ~ .R 4 f; R 7 R ~ n kn ~t

     ,.  ~ .  .

    700 ~
    soo ─

    A 1loo-
     1300─
     1710 _

    DOO _
    1 100 _
    B 1300--
    1 500─
    2600─

    ]3: ~, j~
               ,~
               On-o-f ~7Pf ~
               +1~2

                  ─~15Volt~to4p)
                   ~Battery ~~

       ~ 1 ~,_ _,~
    LM- T ~
    10~3 6 ~ ~,
    ~ 1. 8k

    IIEW BlUE 1081

    ;' PoLs

                     ~ ~ c ~
                      ~ _ ~
                     _ ~v`; ,
                      _ ~ ,
                     . ~ ~ ~

    _

                    1~          ~
                    7 85 4 32 1_ ~ V+\
                    A 8038 (top' e     741 O,u~ ,
                    8 10 ll 12 14 , ,  + V:10- _

    l 1.ol~_> ~ O

    l

                   7 65 4 32 1
                  B 8038(top} e
                   8 10 1112 14

    _ ~_

    r 51 ~

                           I
    For more info see Issues 7,12, } 3 and 14 (Tuning and Using Box)

    The new Intersil 8038CC Function Generator {orms the
    basis of the Multifrequency generator. By varying an exter-
    nal resistorwechange the frequency of the 8038. UnlÜce the
    phase-shift oscillators in Issue 12, however, the distortion
    remains at a low 1~, and the c~rcuit requires only two osc-
    illators instead of 7. The diodes route +10 volts to different
    pots for the different tores. As in Issue 12 a diode matrix
    can be bntlt with two pieces of perf-board forming a diode
    .ia~dwich, bot the new circuit requires 12 lines on one side
    and 9 on the other. 2600 is a s~ngle tone and needs no diode.

    The pots are small 20 turn (or 10 turn) trimmers. They
    can be obtained surplus for under $1 each. If you use sin-
    gle turn pots your resolution will be to~`small to precisely
    calibrate the box, and a small vibration rnay upset the tun-
    ing. Single-turn pots can ouly be used if a series resistor







    ~akes up most of the needed resistance and the pot trims
    ~n the difference, but tbat requlres 10 more resistors and
    time spent determining their value,

    The 8038 Box draws 20 ma., so keep the switch off wLen
    possible. The srnallest 15 volt batteries will work but not
    for too long. A reg~lated supply ~s needed, and the LM-100
    or 300 works fine. The hookup shown supplies 10 volts to
    the circuit. The on-off switch should not be replaced with
    diodes in this box for maximum stability.

    Tuning is super-easy because the 8038's plug into IC
    sockeistdon't bnild it without socketsl) and by inserting 1
    8038, you can calibrate sinale tones eastly. To h~ne 700,
    for example, plug in OscilLator A ouly and press button ~
    l~or 2, 4, or 7) and tune the 700 pot to 700 using a counter,
    or an accurate si~nal generator by ',beatingt' method. 900
    is tuned while pressing 3, 5, OF 8. When youtre done wiEh
    aU 5 tones on one osci~ator, switch the oscillator to the
    B socket and tune the other 5 pots. Then install both 8038's
    and let your fingers do the wa1kin~r

                    LAB NOTES

    We didn't think we'd need the requlator at first but the
    frequency doesn't hold with supply changes as well as it's
    supposed to. Also, 10 volts is the minimum operating vol-
    tage and so is the lowest current dr~in. Slnce the battery
    wears down, itis nice to have a tune margin before the
    supuly volta~e drops. Germanium d~odes are used to min-
    imize differences in voltage drop. Only diodes tbat feed the
    same pot need be matched to each other.

    The 82k resistor is supposed to be 81k for minimum dis-

    V+

    Telephone
    Earniece

    ~ u
    _ 2 7
    + 3 6 Out
    V- -4
    741 Op Amp
    Top ~ NJiews
    ,f~8~>v+
    -~2 6 JOut

                      k34 ~
                        V

    ~r+

    Resistors-1/4 watt, 10~
    Voltaqe Regulator LM-100, or LM-500
    O»~Amo 741CV (National, Signetics, etc. ~
    Oscillator 8038CC (IntersiVavallable from
    Polypaks, Babylon & others.
    Battery-Eveready 411 or 417 15 volt.
    CaPacitors are in Mfd except 47 pf.
    .01 mfd. caps are polystyrene or mylar.
    All capacitors are 15 volts or greater.
    Diodes-small-signal matched germantum,
    or silicon.
    Pots- 25k, 10 or 20 turn trimmers

    tortion but it's unnecessary here. Acaustic coupling induces
    more tban 10~ distortion alone. The best coupling is real-
    ized with a telephone earpiece. To use an 8 ohrn sp=.aker
    you need a 500-8 ohm transformer which isn't worth it in
    our opinion. Earpieces can be disected if you're size con-

    SClOUS.

    We're especially prond of the amplifier circcitry, or to
    be more accurate, the lack of it. Since the 8038's sine
    wave output is referenced to V+/2, we use the outputs to
    bias the op amp to 5 volts? so the 100k mixing resistors
    end up killing two birds with one stone. And ünity gain
    yields 3 less parts and a beautifnl +2dBm at the phone set
    terminals with tight acoustic cougling to the mouthpiece.
    Ihat's ttLe same level (for a single tone) as a Touch-Tone
    phone signali|Felicitas est canis par~rus c~idus, Bell Labs3








    Tha nks to all of you who helped us by sending in your
    ideas for tbis box.
    Dear TAP,
    I've been using this method for acquiring IDs; youlve pro-
    babLy heard of it, bot what the hell. Most univers~ty libra-
    ries have local papers on microfilm. Pick the year you
    want to say you were born and find a child who die] shortly
    after birth; usually the approximate age at death is ~iven.
    Go back to the birth notices and find the child's date of
    birth & parents name. Birth certificates and death cert-
    if icates aren't cross-referenced (at Least where I've ; ~ e

                                      this), and the records office w~l give you a copy ror   .v

    bucks. Ihen you ~et ·Jenuine driver's license, etc. If y
    haven't been fingerprinted it's undetectable.

    The adNIantage of using such a youn~ ch~d is tbat they
    have no records, prints, etc. The advantages of using a
    deccased person are obvious.

    Nct aU papers bother ~vith obituaries for such yo~lng
    people. Sometimes fires, traffic accidents, etc. provide
    the info. If not, you can just work off birth notices. This
    way, thou~h, you could wind up assuminy the ID o, some-
    one with a warrant out on them (You could probably get
    the info. off of tombstones, also). One thing I've been won-
    derin~ ateut is gett~n~ a passport with one of these ll~s. I
    hear that if you go to or.e of the main offices & pay an exLra
    fee, your passport will be processed wEile you wait. Do
    you know, or your readers know, how t~orough a check is
    made? I'.m ~rondertr~g if they mal~e an extra check "or a
    death certificate. If r~ot, Jesus....

    -RHODE ISLAND-

    , ─ ~
    3 zS3
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