(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*) (*) (*) (*) The Lost Avenger And United Phreaker's Incorporated Proudly Presents (*) (*) (*) (*) UPi Newsletter Volume #1, Issue #4 (*) (*) (*) (*) The Extension Silencer & The Tele Mon9jo (*) (*) (*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*)(*) This article was origin published in Popular Electronics - Electronics Hobbyists Handbook. This article was republished without permission. The Extension Silencer By Terrance Kelly This project keeps your modem communications and important private conversations from being interrupted by locking out extension phones when the line is in use. Are you tired of others listening in on your conversation on an extension phone? Do you live with a computer hacker who always seems to want to dial out with his modem in the middle of your of your conversations? Fear no more, three inexpensive parts - which comprise the Extension Silencer - will solve all of your problems. The Extension Silencer described in this article is a simple is a simple circuit that, when placed in series with each of your extension telephones, allows privacy at each location without interference from the others. All phones will ring normally and the first one to answer locks out the others. Someone picking up an extension will hear nothing if the phone is already in use. If you need to switch extension all you have to do is pick up one extension and hang up the other. In order to fully understand the operation of the Extension Silencer, a little discussion on telephone operation is in order. Telephone Operation Each subscriber telephone is connected in what's called a local loop to central office, which contains switching equipment, signalling equipment, and a power source that supplies direct current (DC) for the operation of the telephone system within its coverage area. Switches in the central office respond to string of dial pulses to connect the calling station with the station being called. The Switching array within the central office feeds an AC ring signal down the line to the station being called. When a link is established (the telephone receiver is taken off-hook), the two stations communicate via transformer-coupled loops using DC power supplied by the central office. When the telephone receiver is on-hook, the receiver holds down the hook-switch buttons in the base of the unit, creating an open circuit to DC between the receiver and the central office. The signaling circuit, which is AX operated, is always connected to the central office; a capacitor in the signaling circuit blocks the flow of DC, while passing the AC ring signal. As long as the hook-switch buttons on the telephone are depressed, no communications can take place. However, when the receiver is taken off-hook, the hook-switch closes contacts, passing DC to the telephone, activating the communications circuits, and causing the normal DC line voltage to drop due to the loading effect of the telephone. Circuit Operation The circuit is little more than an electronic cut-off switch built around a Triac (the switching element). Two phone station, A and B, are show to make the circuit's operation easy to understand (Component designations for only one circuit are given in the Parts List). Note that an Extension Silencer circuit is connected in series with each station. Normally when a phone is on hook, the voltage across the phone line is 48-volts DC; when the receiver is taken off hook (is picked up), the DC voltage across the line drops to between 2 and 12 volts DC (typically about eight volts). That's due to the off-hook impedance of the telephone and the loop resistance between the subscriber station and the telephone company's central office. As long as both Station A and Station B receivers are on-hook, the voltage at the gates of TR1 and TR2 is sufficient to trigger TR1 and TR2 into conduction. That means that both Extension Silencer circuits connected to that line are conducting. But when one of the receivers - say station A - is lifted from it's cradle, closing the hood-switch contacts, that telephone draws considerably more power, causing the line voltage at TR2 to drop to around 0.6-volt DC. The operational characteristics of the Triac are key to the operation of the Extension Silencer circuit. Remember that once a Triac is triggered (via a gate trigger voltage), it continues to conduct as long as the current through it remains above it holding-current requirement, even if the trigger source is removed. And will cease to conduct, only when the current through the device is brought below its holding-current level. (In the case of an AC signal, a Triac would be triggered into conduction twice during a single cycle: once during the positive half-cycle, and again during the negative half-cycle. Therefore the 20-Hz ring signal is passed to the phone uninhibited.) The 0.6-volt level at the main terminals of TR2 is too small to generate sufficient current through TR2 to satisfy it's holding-current requirement, so it turns off, disallowing any communications through station B. If the station B extension is take off-hook and station A is hung up, a similar, but reversed action occurs, with station B absorbing the majority of the line-fed power, reducing the current through TR1 to a level insufficient to sustain conduction through that unit. And that in turn locks out Station A. A 15-volt Zener diode was used because that is all the local Radio Shack had in stock, but anything between 12 and 24 volts would have done just fine. The value specified for R1 (1000-ohms) was chosen to yield 35 mA of Zener current. That amount of Zener current may seem excessive, but keep in mind that it is on for a very short time. before a call is answered there is no loop current because the phone-hook switch is open, so there is no Zener current. Construction There is nothing critical about the construction of the Extension Silencer. In fact the author's prototype of the circuit was assembled on a small section of perfboard - half of Radio Shack's 276-148 snap-apart perfboard - measuring about 1 3/4 inches square. The circuit-board assembly was then housed in a modular quick-connect phone-jack cover. Before assembling any components on the board, the two sections must be separated and a hole drilled (through the center of the board) for a wood screw The wood screw will be used for mounting the assembly to the wall. Next, solder the three parts onto the perfboard, interconnecting the components as they are installed. Cut the black and yellow leads from the modular jack as thnce all telephones use the center two conduction of the sres ander them to the boar line. Observe the proper polarity of those wires because the one that attaches to the red wire of the modular jack must connect to the minus terminal of the phone line. Installation WARNING: Remember that all equipment installed on the telephone line must meet FCC part 68 requirements. The equipment must be certified by an authorized agent before it is used on the network. (This article is meant to be of instructional value and not as a certification for FCC approval.) Since my house had phone jacks with screw terminals inside all I had to do was remove the face-plate and measure the voltage across the connection-block terminals. The connection block has four screw terminals labeled L1-L4. In most cases, the terminals of the connection block are tied to the telephone line via a quad color-coded cable - red, green, yellow, and black. (Older installations use twisted twin lead tied into the telephone line.) Normally, the read and green wires are used as the communications pair, and are connected to the L1 and L2 terminals. With my VOM, I determined the polarity of the phone line. If the positive lead of the meter is on L1 and the negative lead is on L2 and the meter reads a positive 48-volts DC, then L1 is positive with respect to L2. If it reads negative, then L2 is positive with respect to L1. In my own installation, the minus lead was attached in parallel with the L2 terminal (you may find it to be the L1 terminal) on the phone jack. The plus terminal was then connected in parallel with the L1 Lead. Remove the phone from the normal hack and insert its plug into the Extension Silencer jack, and you are ready to go. Pick up the phone with the silencer and listen for dial tone and hang up. Pick up the extension without the silencer and leave it off hook. Pick up the phone with the silencer and it should be "dead". Hang up the phone without the silencer and there should be audio from the "dead" phone. You can now add as many Extension Silencers as you have phones. For those readers who have a "smart modem", set it to return "NO DIALTONE" if the line is in use. Also set it to keep retrying so that you can capture the line should it ever become free. Part List For The Extension Silencer TR1 1-amp, 50-PIV Triac R1 1000-ohm, 1/4 watt, 5% resistor D1 1N4744, 15 volt, 1-watt Zener diode (Radio Shack 276-564, or similar) Dual Board Perfboard (Radio Shack 276-148) Quick-Connect Modular Jack (Radio Shack 279-355) Clear View Speaker Wire (Radio Shack 287-008) Solder Hardware To To Telephone 3 MT1 MT2 Telephone Line 3 3 3 ZDDDDDDVVV TR1 3 3 3 3 3 1A 3 3 3 3 R1 3 50 PIV 3 3 3 3 1k 3 3 3 3 @DDDDVVVVDDDD*DDDDDDDDDVVVVDDDDDDY 3 3 D1 3 3 Station A 1N4744 3 3 15v 3 3 @DDDDD3DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD> To 3 MT1 MT2 Telephone @DDDDD*DDDDDDDDDDDDDDDDDDDVVVDDDDDDDDDD*DDDDD> 3 ZDDDDDDVVV TR1 3 3 3 1A 3 3 R1 3 50 PIV 3 3 1k 3 3 @DDDDVVVVDDDD*DDDDDDDDDVVVVDDDDDDY D1 Station B 1N4744 15v The Tele Monitor By Charles R. Ball Jr. And W.K. Ball Now you can keep an audible record of your telephone conversations with the aid of this simple circuit. WARNING: The use off the Tele Monitor and the parts therein is governed by Federal and State law. Federal law prohibits the taping of telephone conversation by one party without the knowledge and/or consent of the other party. Many states have adopted identical or similar provisions. Prospective users are advised to obtain independent advice as to the propriety of the purchase and use of the parts and use of the Tele Monitor, including (but not limited to) taping conversations therewith. We make no representations concerning the parts referred to in this article of their use or the legality of the use of the Tele Monitor, or any other such equipment referred to in this article. Readers are advised to obtain independent advice as to the propriety of their use of the parts, the Tele Monitor, or similar equipment based on their individual circumstances and jurisdiction. Remember when your sister called to tell you about this year's family reunion, but in the excitement of hearing from her, you forgot to write down the date, time, or even the city? How often have you talked on the phone with a client for an extended period and after hanging up, remembered that you hadn Well, such memory lapses need not be a problem if you build the Tele Monitor described in this article. The Tele Monitor automatically activates a recorder to keep a perpetual log (within the limits of the tape's capacity) of all call, incoming or outgoing. Best of all, it can be built for less than $25, excluding the recorder. How It Works The circuit is connected between the telephone line and the tape recorder. The telephone line - the conductors are designated tip and ring - normally has -48 volts across it when the telephone is on hook. When the telephone is off hook, that voltage changes to about -10 volts, depending on the subscriber loop resistance. A full-wave bridge rectifier (consisting of D1 through D4) connected across tip and ring allows the circuit to be tied to the telephone line without regard to polarity. The voltage applied across tip and ring appears, polarity corrected, at the + and - ends of the diode bridge. When the phone is on hook, the voltage through D5 keeps Q1 on and Q2 off, so the recorder is in an idle state. When any telephone tied to the circuit is picked up (an goes off-hook), the voltage across tip and ring drops to about -10 volts, causing Q1 to turn off and Q2 to turn on, activating the recorder through J2. Incoming calls also activate the recorder with each ringing cycle. When the phone is off-hook and the recorder is running, voice is coupled through R1 and the C1/C2 combination. Because the central-office ringing voltage is 105-volts AC, C1 and C2 - which must have a voltage rating of 150-volts or better - are connected back-to-back to simulate a non-polarized capacitor. The diodes, D1 through D4, should have a peak inverse-voltage (PIV) rating 200 volts of better. Power for Tele Monitor is derived from the telephone line. A very small current (less than 80uA) is derived from the telephone line through the diode bridge when the phone is on-hook, so that Q1 remains off, keeping the recorder is an idle state. (CAUTION: For use in this application, the recorder must be battery operated or powered with a UL/CSA/FCC approved adapter. Nether the telephone company or the FCC take kindly to having 120-volts AC suddenly appear on the telephone line.) It is recommended that the Tele Monitor circuit be coupled to a recorder with automatic volume control to compensate for varying signal levels on different calls and varying speech characteristics. The recorder mentioned in the Parts List is one such recorder. Other recorders can be used, but you must be sure that the internal remote-jack connections have the proper polarity for Q2 to turn on the recorder. Assembly The author's prototype of the Tele monitor was assembled on a printed circuit board measuring about 2 3/4 X 2 1/4 inches. The layout provides for two modular connectors that allow you to connect your phone and the Tele Monito Once you have obtained or etched the board and are in possession of all the components, begin assembling the project using the project. When stuffing the board, be careful of component orientations, particularly the diodes, capacitors, and transistors. Transistor Q2 should be heat sinked because the combination of the saturation drop in Q2 and motor current in the recorder may exceed the transistor's ambient thermal rating. Usually a small clip-on heat sink is adequate. Next, prepare a cable for connection to the remote jack of the recorder. Select a plug that's suitable for mating with the remote jack of your recorder. almost any wire will do, but for ease of soldering to the plug, 24 to 26 gauge stranded wire is recommended. Make sure that the circuit-board pad marked "T" is connected to the "tip" of the remote plug and and "R" to the other lug of the plug. After soldering the wires to the plug, twisting the wires about 2 turns per inch will prevent the cable from tangling. If you are using a recorder other than the once listed, check the recorder schematic to ensure that the circuit is properly connected to the recorder. Next, prepare a cable for connection to the mike jack. Again, you must select a plug that's suitable for mating with the jack of your recorder. The use of shielded audio cable is recommended. Solder the prepared cable to the appropriate circuit-board pads. Once the board is assembled and the cables connected, clean the flux from the board, especially in the area of the modular connectors. Solder flux, when damp, is conductive and can cause erratic operation. Also check for misoriented or misplaced components, solder bridges, cold solder joints, and all the other construction errors common to hobby electronic projects. You must also prepare or purchase modular plug-to-plug telephone cable (both ends terminated in modular plugs), which will be used to connect the circuit to the telephone line. Radio Shack sells them in varying lengths, with either coiled and flat cable. If a cable of greater length than is available is needed, it will be necessary to make your own. All of the equipment and material needed to handle that task is available from Radio Shack as well. Preparing the Enclosure A circuit is required for the modular telephone sockets, SO1 and SO2. Two cutouts can be made (one for each socket), or a single long one, as shown. A nibbling tool, available at electronic stores, is ideal for performing the task. Make sure that you check the orientation of the board before making the cutout; the enclosure has only two posts for mounting the board. Position the board, component-side down with the two mounting holes lining up with the mounting posts to determine which part of the enclosure to cut. Next, drill two holes for the recorder remote and mike cables. A 3/8-inch hole for each will be adequate. It is recommended, however, that a 3/16-inch hole be drilled and reamer used to enlarge the hole to the desired size. Plastic is tricky to drill, and some plastics drill easier than others. The plastic used to make the enclosure listed in the Parts List will chip, crack, grab, or self destruct if you use large size bits. Drill speed is also important; generally, the slower the drill sped the better. Checkout There are a number of ways to check out the circuit. First, check the orientation of each component against the diagram and check all solder joints. If you have a power supply capable of providing at least 50-volts DC, you can check the Tele Monitor without connecting it to the telephone line. Attach the power supply leads to the tip and ring leads of the modular sockets. Connect J2 to the remote jack of the recorder. Press record and play as you normally would to record. With the 50-volts DC power supply on, the recorder should be "off;" with the supply off, the recorder should be running. If you don't have access to be a 50-volts DC supply, it will be necessary to use the telephone line as your power source. As before, connect the circuit to the recorder. Install one of the modular plug-to-plug cable in one of the Tele Monitor sockets and the other end in the wall. Either connect a phone to the Tele Monitor or use another phone on the same line for the following test. Pick up the telephone. The recorder should start; press "1" on the telephone to eliminate the dial tone, and speak a few words into the mouthpiece in a normal voice and hang up. The recorder should stop once you have hung up. Remove the remote plug from the recorder, rewind the tape, press play and then check the voice quality. Final Assembly Once the case is prepared and the circuit checked out, route the recorder cables through the proper holes, position the board in the case with the components facing down and the modular sockets lines up with the cutout. Secure with the two screws supplied with the enclosure. Mount the cover using the remaining four screws. If everything checks out, you are ready to monitor. Make sure the remote and mike plugs are connected, that the modular jack is connected to the telephone wall jack, press record and play and you are all set. Happy monitoring. Telephone Subscriber Line Specifications Parameter Value Condition Central Office voltage, tip to ring -48 VDC On-hook Central Office voltage, tip to ring -10 VDC Off-Hook Central Office voltage, tip to ring 105 VAC, 20/30 On Hook, Ringing Subscriber loop current, tip to ring -20 to -80 mA Off-hook, CO Seizure Subscriber loop resistance, tip to ring 0 to 1200 ohms Off-hook Parts List For The Tele Monitor Semiconductors Q1 TIP120, NPN darlington transitor Q2 TIP42, PNP silicon power transitor D1-D4 1N4004 1-amp, 400-PIV rectifier diode D5 1N4748A, 22-volt, 1-watt Zener diode Resistors (All resistors are 1/4-watt, 5% units.) R1 4300-ohm, 1/2-watt, 5% R2 1-megeohm, 1/2-watt, 5% R3 150,000-ohm R4 390-ohm Additional Parts And Materials C1-C2 1uf, 200-WVDC, electrolytic S01-S02 Modular telephone socket PL1 See text PL2 See text Printed circuit Enclosure (Radio Shack 270-283 or equivalent) IC Socket (optional) Heat sink (AAVID 5741B or equivalent) Modular telephone plug with cable (Radio Shack 279-397, 279-374, or similar) Recorder (Radio Shack CTR 70 or equivalant) Note: The following items are available from BALLco, Inc., PO Box 1078, Snellville, GA 30278-1078; 404/979-5900; etched, drilled, plated and silk screened printed circuit board (#881101-R0), $9.95 post paid in the USA; a complete kit (#TM88) less case and recorder plugs for $24.95 + 2.50 shipping and handling. And assembled Tele Monitor is available for $39.95, plus $2.00 S/H. A case for unit is available for $3.99 post paid. Florida and Georgia residents pleases add appropriate sales tax. ZDDD*DDDDDD*DDDDDD? 3 3 3 3 3 D1 D2 D5 ZDDDDDDDDDDDDDDDDDD*DDDDD? 3 1N4004 1N4004 1N4748A 3 3 3 3 3 3 22V 3 3 3 *DDDDD*DDDDDEDDD* 3 3 3 ZDDDY 3 SO1 3 3 3 3 3 ZDDD4 ZDDDDD4Q2 TIP42 3 *DDDDDEDD*DDEDDDEDDDDDD* @DR3DDDDD*DD4 ZDYQ1 3 @DDD? 3 3 3 3 3 3 150K 3 @D4 TIP120 3 3 3 3 3 3 3 3 3 @DDDDDDDDDD* 3 PL2 3 3 3 D3 D4 3 3 @DDDDDY 3 3 3 1N4004 1N4004 R2 R4 3 3 3 3 3 1MEG 390Ohms 3 3 3 3 3 3 3 *DDDDDY 3 3 @DDDDDD*DDDDDD*DDDDDDDD*DDDDDDDDDDDDDDDY SO2 3 3 3 *DDDDDDDDY 3 PL1 3 3 @DDDR1DDDDDC1DDC2DY 4.3K 1 1 [$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$] !! !! !! U P i - U N I T E D P H R E A K E R ' S I N C O R P O R A T E D !! !! !! [$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$] Last Updated: July 16, 1991 Members: Chairman of the Board: The Lost Avenger (416/Ontario) Board of Directors: Dantesque (416/Ontario) Scarlet Spirit (416/Ontario) Members of the Company: Grim Reaper (613/Ontario) Logic Master (514/Quebec) Master of Gold (54/Argentina) Seven Up (61/Australia) Tyler (215/Pennslyvania) Addresses: Internet E-Mail: tla@pnet91.cts.com UUCP E-Mail: utzoo!pnet91!tla QSD Mail Box (NUA: 208057040540): The_Lost_Avenger or UPi Node Listing: ------------------------------------------------------------------------------- Node BBS Name Area Baud Megs BBS Sysop Number Code Rate Program ------------------------------------------------------------------------------- WHQ The Violent Underground 416 2400 85 PcBoard The Lost Avenger Node #1 The Shining Realm 416 9600 95 Telegard Scarlet Spirit Node #2 The Blue Zone 613 2400 80 Telegard Grim Reaper ------------------------------------------------------------------------------- New members from anywhere in the world will always be welcome. If you wish to join the group, you must logon to the Shining Realm and acquire an account. Once that's done, you need to ask TLA or SS for the UPi questionnaire to be used to evaluate you. Once you pass, an email of congratulations will be sent to you and you will be able to participate fully in the group in addition to getting your name on this elegant introduction screen. Impress chicks with how you're a member of a premier international organization of freelance anarchists with the capability to reach out and touch a globe. [$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$] !! !! !! U P i - U N I T E D P H R E A K E R ' S I N C O R P O R A T E D !! !! !! [$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]==[$]