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TUCoPS :: Phreaking General Information :: scramble.htm

Build a Telephone Scrambler!



Telephone Scrambler Protect your confidential telephone calls against intrusion with this easy-to-build scrambler. Scrambling is the most effective method for eliminating unwanted evesdropping on your confidential calls. It should be considered if you have reason to believe that unauthorized persons are or could be listening in. A system consisting of two compatible telephone scramblers will permit normal conversation between you and your intended listener, while making all speech unintelligible to anyone listening in at either end of the line. Only persons with a compatible unscrambler will be able to understand what is being said. (Fig.1) Complete telehpone security is obtained with a TVS250 at both ends of the phone line forming a duplex scrambler/descrambler system. [Headset]-[TVS250]-[Phone]-[Phoneline]-[Phone]-[TSV250]-[Headset] Circuit Design The COM9046 voice scrambler/descrambler IC contains a crystal oscillator that that controls system timing. The onchip oscillator requires an external 3.58- MHz crystal that is commonly used in TV color-burst applications. The chip also contains switched-capacitor filters, so input speech must be filtered by an anti-aliasing single-pole, low-pass filter before it is applied to the audio input. Parts List All resistors are 1/4-watt, 5%, unless otherwise noted R1 100,000 ohms, PC-mount potentiometer, screwdriver adjust R2 500,000 ohms, PC-mount potentiometer, screwdriver adjust R3,R4 10,000 ohms R5,R6 3900 ohms R8,R9 100,000 ohms R10-R13 1000 ohms R7,R14,R15 51,000 ohms R16-R18 2200 ohms R20 150,000 ohms R21 5100 ohms Capacitors C1,C2 15 pF, ceramic disc C3-C10 0.1 uF, metal film C11,C12 2200 pF, ceramic disc C13-C15 0.001 uF, ceramic disc C16 1uF, 35 volts tantalum C17,C18 10 uF, 16 volts, electrolytic polarized Semiconductors IC1 COM9046 voice-scrambling IC, (Standard Microsystems) IC2 MC34119, audio amplifier driver (Motorola or equiv.) IC3 LM358 dual operation amplifier, single supply IC3 78L05A, 5-volt regulator (Texas Inst. or equiv.) Q1 2N2222A, NPN transistor LED1 green light-emitting diode, T1, 5mm LED2 red light-emitting diode, T1, 5mm Other Components S1 SPST slide, PC-mount, side-actuated switch S2 SPST slide, PC-mount top-actuated switch S3-S6 STS2400 PC, 2P4T slide, PC-mount, top-actuated (Augat/Alcoswitch or equiv) switch J1,J2 telephone jack 4-4, Type 616, PC-mount JU1-JU4 two-post jumper, 3/32 inch-on-center with insulated shorting clips XTL1 crystal 3.579545 MHz, metal case (ITT 4183 or equiv.) B1 9volt transistor battery, alkaline, standard Miscellaneous TVS250 PC board, 5-inch length of telephone cord terminated with standard telephone plugs, 9-volt transistor battery clip-type holder (Keystone No. 79 or equiv.) with two 2-56 screws and nuts, 9-volt transistor battery terminal snap with leads, four rubber or plastic PC board feet and solder. :Note: The following parts are available from Securicom, P.O. Box 5227, Chatsworth, CA 91313-5227 (818) 710-0110 * COM9046 scrambler/descrambler IC only - $18 * Double-sided, silk screened and drilled PC board - $20 * A complete kit including PC board, all components, and 5 inch plug- terminated phone cord - $59.95 * Assembled and tested TVS250 with user's manual - $79.95 (Fig.2) +5V | |--| o------| |-----~--o--- 2.2k R17~ R4~10k | R2 | o---<>-o----|--*+**** | R11 R5 | C3 | | *IC3a*---o--~---<>---o--~------o--(3) MIC+-----0^0| | o--*-**** C4 | | JV4 | | | C11$ R3 ~ | C5 | R6 | MIC------0^0-------| |---~---<>--# |-<>-o-|--~---o-----(2) JV3 # R21 C8 | | | C12$ | | | | |--| (Cont fig.3) | | | | Base audio Signal------------------------| | | # R8~ ~R9 Base audio GND------------------------# | | --o---------o--(1) | | | | | (Fig.2) S1 ****** |---@----* IC4*---o--o--o-->+5v | ****** | | | | | | | ~R13 = | C10<> <>C17 |B1 | | | | | | | | L LED Green =----------0------o--o--| | # (Fig.3) C1 XTAL +5v --<>--o-&-o---<>- ^ | | | | | # o-~-o # |---o |R19| | | ******* | L LED2 3--* * | ~ R10 * *------|---o--S2----------------# 2--* IC1 * | | * *------|-| <>C6 * * | | # R20 /JV1-- * * | |---------~-------Q1 Mic Input to Tele Base * * | \JV2-- * *------|---| * * | | * * | | * *--o---o | 1--o--* * | | | | *******--| | | | | | | | | o o R18~ ~R14 C14 | |---|--<>---o o---------<>---------------| | | | C18 | | ^+5v | | | | | | R15 | | | | o--<>---o |---~-----o-----******* | | | | C7 | | *IC3-b* | | | # | C13<> *+ *----o | | | | * * | | |-----------o # * * | |---------------| C9 *- * | <>----~---o--******* | -------~---------| R12 | | | | R7 | # | | C15 # |-------------| | |--<>---|------| | | | | |--------o---****|**** | Handset speaker | * *--|------------------> ---------|---* IC2 * | | | * * | Handset speaker <>C16 | * *--o------------------> | |--|---********* | o-----| | R1 | # |----o---~-----| | | |---| (~)=Resistor (<>)=Capacitor (@)=Simiconductor I recomend that you call and purchase a better diagram for the TVS250 from the company listed above. Remember, to make the scrambler work you must have two TVS250's, one on the callers phone and another on the receivers phone. I haven't purchased a set yet, but this DOES work, information was gathered from radio electronics. So, it is a reliable source, not just another dumb text file. Good luck! ->BB<-


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