How to build a black box -- (found on textfiles.com)
by Unkown
To all who dare --
What is a BLACK BOX? A BLACK BOX
is a device that is hooked up to your
fone that fixes your fone 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 Fone Co. gets suspicious, and then
you can guess what happens.
What this little beauty does is
keep the line voltage from dropping to
10v when you answer your fone. The
line is insted kept at 36v and it will
make the fone think that it is still
ringing while your talking. The reason
for the 1/2 hour time limit is that the
Fone CO. thinks that something is wrong
after 1/2 an hour of ringing.
All parts are available Radio
Shack. Using the least possible parts
and arangement, 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 small PC
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
!--/\/\/\--!>--!
! !
------>/<-------
SPST
Parts: 1 1.8k 1/2 watt resistor
1 1.5v LED
1 SPST switch
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 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
************** ****************
* * * ------- *
* --<LED>--- * * ! ! *
* ! ! * * ! <SWITCH> *
* RESISTOR ! * * ! ! ! *
* ! ! * * ! ! / *
* -------- ! * * ! ! \ *
* ! ! * * ! <LED>! / *
* --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.
How to find out:
Hook up the box in one direction
using one set offor line and the
other for fone.
*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
lable the switch in its current
position as BOX ON.
How to use it:
The purpose of this box is not to
poeple who call you so it would make
sence that it can only be used to
receive! calls. When the box is *ON*
then you may only recieve calls. Your
fone will ring like normal and the LED
on the box will flash. If you answer
the fone now, then the LED will
light and the caller will not be charged.
Hang up the fone after you are done
talking like normal. You will not be
able to get a dial-tone or call when
the box is on, so turn the box *OFF*
for normal calls. I don't recommend
that you leave it on all the time, as
you don't want it to answer when Ma
Bell calls!
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