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-
-
- ==Phrack Inc.==
-
- Volume Three, Issue Thirty-five, File 9 of 13
-
- ////////// //////////////////////////////////////
- // C // // //
- // r // // A U T O - A N S W E R I T ! //
- // e // // //
- // a // //////////////////////////////////////
- // t //
- // e ////////////////////////////////////////////
- // d B y : T w i s t e d P a i r //
- ////////////////////////////////////////////////////
-
- Many times I've wanted to be able to start and/or listen to devices at my
- home when I'm somewhere else. I've developed the following circuits to do this
- for me. The circuits have all kinds of uses. I'll let your mind ponder the
- endless fun activities you can have. Some of the things I have used them for
- are monitoring my own house, tape record my friends for fun without their
- knowledge, or listen to a radio station when you're out of town, etc.
-
- ///// Automatically Answer a Phone /////
-
- This has got to be the best way to automatically answer the phone. With
- just 2 parts, we can couple an audio source into a phone line. The cost will
- be less than $5 no matter where you get the parts!
-
-
- . . Radio Shack
- . . / ECG 6412 273-1374 Transformer
- Red __ __ Diac /
- (+) O-------------I\ /I------------) || (---------O <-
- Tip . \ / . ) || (
- ._\____/_. ) || ( Audio Source
- . . ) || ( feeding IN
- Green ) || ( to transformer
- (-) O-------------------------------------) || (---------O <-
- Ring
-
- The "Diac" or "Bilateral Trigger Diode" looks like an open circuit until a
- voltage of either polarity is applied that is above its threshold of 63 Volts.
- (plus or minus 7 Volts) When this voltage is exceeded, like when the line
- rings, the device acts as a switch and goes into conduction. This "answers"
- the phone and holds the line through the transformer, which couples the audio
- to the line.
-
- When the caller hangs up, most telephone companies provide a momentary
- reversal of Tip and Ring which causes the Diac to stop conducting and release
- the line.
-
- ///// Another Way to Automatically Answer /////
-
- For those who want to really play with this circuit, I suggest the
- following additions. I have added a bridge rectifier and an optical coupler to
- the circuit. The bridge just makes sure that the LED inside the optical coupler
- gets the proper polarity. If you are careful to observe polarity when
- connecting to Ma Bell, you can leave out the diodes and save a little money.
-
- . .
- . . Radio Shack
- |----------|-----------------__ __---------------| 273-1374
- | | .I\ /I. | Transformer
- --- --- ._\____/_. |--) || (-----O
- \ / \ / . . ) || (
- --- --- ECG 6412 ) || ( Audio
- O---| | Diac ) || ( Source
- Tip | O----| 1N4003 Diodes ) || (
- (+) | Ring | ( 4 ) |--) || (-----O
- --- (-) --- ECG 3045 Optical Coupler |
- \ / \ / ______________ / |
- --- --- | | |
- | | 2 | |\ | | 1 |
- -------------------------------| \|------------------|
- | |/ | |
- | |
- | \ \ |
- | v v |
- | ________ |
- | / \ |
- | V \ |
- |___|______|___|
- | |
- 4 5
-
- Pins 4 and 5 on the optical coupler can be wired to remotely start a
- device upon answering the line. An example would be a tape machine or battery-
- powered bugging amplifier. Be careful not to connect anything over 25 volts to
- pins 4 and 5 to avoid frying the opto-coupler. Either circuit will accommodate
- an extra LED that could be used as a status indicator. Just be sure to keep
- the polarity proper and put it in series with the other components.
-
- The Audio Source can be almost ANYTHING. If you want to hook up a
- microphone as the Audio Source, connect the microphone to some kind of
- amplifier first, then to the transformer.
-
- ///// An Interesting Catalog to Read Through /////
-
- If you really want to get fancy, you could consider ordering a free
- catalog from Monroe Electronics. They sell the following products you might
- wish to play with. Use these as building blocks to make whatever you need...
-
- DTMF Decoders (a) Which provide a momentary or latching relay
- ------------- output for the duration of time the DTMF digit
- is being pressed. (If you're really obnoxious,
- you'd use one of these with one of the above
- circuits. Then you could call and randomly turn
- things on and off like maybe a TV scrambler/
- jammer.)
-
- (b) Which can accept multiple digits and be programmed
- for a momentary or latching relay output. (Use one
- of these to make a DTMF combination lock for your
- BBS. Or use as a call screener, i.e. only the
- correct DTMF sequence could make your phone actually
- ring)
-
- (c) Which can control access by a 4 digit code to latch
- a relay, then a single digit to unlatch it. (A
- little bit more sophisticated than (b) above.
-
- DTMF Encoders Which can convert BCD to DTMF tones. Crystal-
- ------------- controlled, of course. 600-ohm audio output.
- (Use one of these to convert your computer's
- output into ANY DTMF tones of your choosing. You'd
- be able to choose the duration as well! Then this
- circuit would couple your evil DTMF into the phone
- line)
-
- Audio Detectors Detect BUSY and DIAL TONE and operate a relay.
- --------------- (Useful when making scanning hardware/software
- applications)
-
- Audio Generators Generate Ring Tone, Dial Tone, Busy Tone, Tone
- ---------------- Burst, etc. (Start your own phone company. Fool
- your friends, trip out the operator)
-
-
- Dial-up DTMF remote control systems which can be used to control and
- monitor remote relays and status inputs at unattended sites.
- They can also provide automatic dialing of stored phone numbers to
- report status of inputs, and can make use of an internal timer to
- execute control commands. (Water strange plants by call-in remote
- control, check moisture levels, see if a certain mailbox is empty
- or full, have the mailbox CALL you when something is delivered,
- etc. Do I have to tell you everything? Just get the catalog!)
-
-
- Their address is:
- MONROE ELECTRONICS, INC.
- 100 HOUSEL AVENUE
- LYNDONVILLE NY 14098
- (716) 765-2254
-
- //////////////////////\/\/- T W I S T E D P A I R-/\/\////////////////////////
- _______________________________________________________________________________
-