*************************************** * * * How to build a BLACK BOX * * * *************************************** (Also known as mute box) 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. The way it works: 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 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-- * * ! ! \ * * ! ! * * ! ! / * * ! ! * * ! ! ! * 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 of wires for 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 switch was in the wrong position. = Now 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!