Black Box Plans

Introduction

What is a BLACK BOX? A BLACK BOX is a device that is hooked up to your phone that fixes your phone so that when you get a call, the caller doesn't get charged for the call. This is good for calls up to 1/2 hour, after 1/2 hour the Gestapo (the you can guess what happens).

The Way It Works

What this little beauty does is keep the line voltage from dropping to 10v when you answer your phone. The line is insted kept at 36v and it will make the phone think that it is still ringing while your talking. The reason for the 1/2 hour time limit is that the Gestapo thinks that something is wrong after 1/2 an hour of ringing. (I mean, come on)

Phone Modification Instructions

All parts are available Radio Shack. Using the least possible parts and arrangement, the cost is $0.98; and that is parts for two of them! Talk about a deal! If you want to splurge then you can get a board, and a switch. There are two schematics for this box, one is for most normal fones. The second one is for fones that don't work with the first. It was made for use with a bell trimline touch tone fone.

                      **  Schematic 1 for most fones  **
                      **         LED ON: BOX ON       **

                    FROM >--------------------GREEN->  TO
                    LINE >--!   1.8k  LED  !---RED--> FONE
                            !--/\/\/\--!>--!
                            !              !
                            ------>/<------- 1 PARTS: SPST

*You may just have two wires which you connect together for the switch.


                       **  Schematic 2 for all fones  **
                       **        LED ON: BOX OFF      **
                     FROM >---------------GREEN->  TO
                     LINE >-------      ---RED--> FONE
                                 !  LED !
                               ---->/<--!>--
                               !         !
                               ---/\/\/---
                                  1.8k

    Parts:  1 1.8k 1/2 watt resistor
            1 1.5v LED
            1 DPST switch

Here is the PC board layout that I recommend using. It is neat and is very easy to hook up:

                      Schematic #1        Schematic #2

                     **************     ****************
                     *            *     *  -------     *
                     * ----- *     *  !     !     *
                     * !        ! *     *  !   *
                     * RESISTOR ! *     *  ! !      !  *
                     *        ! ! *     *  ! !      /  *
                     * -------- ! *     *  ! !      \  *
                     * !        ! *     *  ! ! /  *
                     * --SWITCH-- *     *  !      ! \  *
                     *  !      !  *     *  !      ! /  *
                   L *  !      !  * F L *  !      ! !  * F
                   I>RED-      -RED>O I>RED-      ---RED>O
                   N>-----GREEN---->N N>-----GREEN------>N
                   E * h          * E E *              * E
                     **************     ****************

Once you have hooked up all the parts, you must figure out what set of wires go to the line and which go to the fone. This is because of the fact that LED's must be put in, in a certain direction. Depending on which way you put the LED is what controls what wires are for the line & fone.

In order to find out, hook up the box in one direction using one set of wires for line and the other for phone.

             *NOTE*  For Model I switch should be OFF.
             *NOTE*  For Model ][ switch  should  be
                    set to side connecting the LED.

Once you have hooked it up, then pick up the fone and see if the LED is on. If it is, the LED will be lit. If is doesn't light then switch the wires and try again. Once you know which are which then label them. *NOTE* - If neither directions worked then your switch was in the wrong position. Now lable the switch in its current position as BOX ON.

Black Box Usage

The purpose of this box is not to people who call you so it would make sense that it can only be used to recieve calls. When the box is *ON* then you may only recieve calls. Your phone will ring like normal and the LED light on the box will flash. When you answer the fone the LED will light and the caller will not be charged. Hang up the fone after you are done like normal. You will not be ab