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- BLACK BOX MODS FROM JACK PLUG got 1/12/91 runaway a500
- =============================
- THE BLACK BOX CHARGE INHIBIT CIRCUIT CURRENTLY CIRCULATING
- AGAIN (6.1K RESISTOR, LED, CAPACITOR, DIODE, ETC) SEEMS NOT
- TO WORK ON SEVERAL SYSTEMS. A USEFUL MOD IS TO REPLACE THE
- EXISTING RESISTOR WITH A VARIABLE TYPE. CHOOSE EITHER A 0 TO
- 10K OR A 0 TO 1K VALUE TYPE AS MANY INSTRUMENTS CAN BE
- "BALANCED" WITH QUITE LOW ADDITIONAL RESISTANCES. TRIMMERS OR
- PRESETS ARE THE CHEAPEST, BUT FOR EASY AND ACCURATE
- READJUSTMENT GO FOR THE MULTI-TURN CERMIT TYPE OR SIMILAR.
-
- TO SET-UP, INSTALL THE BLACK BOX AND SET THE RESISTOR TO ITS
- LOWEST VALUE POSITION (FULLY ANTI-CLOCKWISE). WITH THE BOX
- OFF, LIFT THE HANDSET AND CHECK FOR A DIALLING TONE. NOW
- SWITCH THE BOX "ON" AND CHECK THAT THE TONE REMAINS. THE NEXT
- STEP IS TO GRADUALLY INCREASE THE RESISTANCE, CHECK FOR THE
- DIAL TONE, INCREASE THE RESISTANCE, CHECK FOR THE TONE.... AND
- SO ON UNTIL A POINT IS REACHED WHERE THE DIAL TONE EITHER
- FLUTTERS OR DISAPPEARS COMPLETELY. AT THIS POINT DECREASE THE
- RESISTANCE S L I G H T L Y.
-
- WITH A VOLMETER CONNECTED IN PARALLEL ACROSS THE LINE YOU
- SHOULD NOTICE THE USUAL VOLTAGE DROP WHEN THE HANDSET IS
- LIFTED AND THE BLACK BOX OFF. wITH THE BLACK BOX ON, HOWEVER,
- THE OFF-HOOK VOLTAGE DROP SHOULD BE CONSIDERABLY LESS.
-
- IN USE, THE BOX SHOULD BE SWITCHED ON WHEN SOMEONE RINGS YOU
- OR WHEN YOU HEAR THE RINGING TONE OF THE PERSON YOU ARE
- CALLING. IF THERE IS ANY JUSTICE, WHEN THE BOX IS SWITCHED ON
- THE EXCHANGE METER WILL "SEE" THE VOLTAGE SWING ASSOCIATED
- WITH YOU REPLACING THE HANDSET AND STOP COUNTING. ENOUGH
- CURRENT REMAINS, HOWEVER, TO FIRE-UP THE MIC AND FACILITATE
- CONTINUANCE OF THE CONVERSATION. SOME ODD THINGS HAVE HAPPENED
- WHILST WATCHING OTHERS USE THIS DEVICE (!). AT ONE POINT, THE
- BOX SWITCH WAS CLICKED OFF AND ON QUICKLY DURING A
- CONVERSATION AND A DIGITISED VOICE ANNOUNCED THAT "RECALL IS
- NOT AVAILABLE, YOU WILL BE RECONNECTED TO THE CALLER," AND THE
- CREDIT DISPLAY IN THE PHONE BOX THAT HAD INITIATED THE CALL
- PROMPTLY STOPPED CLOCKING DOWN.
-
- I HOPE THIS IS OF USE TO SOMEONE. REGARDS: JACK PLUG.
-
- (BY THE WAY, I HAVE FOR SALE OR SWAP A "MOULD" SELCALL UNIT.
- FULLY OPERATIONAL WITH INTACT EPROM/CALLSIGN. WANT VERY CHEAP
- TNC OR RTTY INTERFACE. DESPERATELY NEED CIRCUITS/INFO ON
- "TEMPEST.")
- PHREAKING TELEPHONE CIRCUITS
- ============================
- This is one version of the many Black
- Boxes Available:
-
- Circuit Diagram
- ===============
- -------O------S1------O-------
- : ! ! :
- L ! ! :
- I O------D1------O P
- N ! ! H
- E ! ! O
- : O---D2----R1---O N
- I ! ! E
- N O------C1------O :
- : :
- ------------------------------
-
- List of Bits
- ============
- S1 - SPST (Toggle Switch !!)
- D1 - 50-200 volt diode (IN400x range)
- D2 - Standard LED (Red is nice !!)
- R1 - 6.1K Resistor
- C1 - 1uf Non polar capcitor
-
- Notes
- =====
- (The diodes are positioned as follows)
-
- D1 ------->!-------
- D2 -------!<-------
-
- Theory
- ======
- When a phone is answered there is normally approx 100MA DC
- loop current but only 80MA or so is necessary to polarise the
- mic element.
-
- R1 Limits the Loop Current
- C1 Ensures speech is unaffected
- S1 Is used to turn the circiut off/on
- for outgoing calls or for Operator
- Calls etc
- D1 Tells you its working
-
- Practice
- ========
- Leave switch off till you hear it ringing, then switch the
- circuit on.
- Basically it just fools the Telephone system into thinking that
- you have put the phone down. Also if you leave it on all the
- time incoming calls are not charged.
-
- Snags
- =====
- Have fun,but remember it works for local calls only. Long distance
- calls will be disconnected after 3 mins..
- Cheers <NUT>
- PS. Before I go
- ---------------
- Q. What have Flamingo's and BT got in
- common ?
- A. They can both stuff there Bills up
- there Arse !!!!!
-
-