|
Mark - IN.
01-04-2005 20:44:43
|
|
Re: Another OT; Main entrance gate intercom in reply to Mark - IN., 01-04-2005 20:21:26
|
|
| |
Many years ago at a army installation in Germany, I ran a pair of wires about two miles from a building to a gate for a ringer so didn't have to post a guard around the clock at the gate to let an occasional guest in. Took the pair of wires and ran them to 110/120VAC. The hot side of the AC ran out to a spring loaded switch at the gate (had a sign saying "press button to be let in") through one of the wires, through the switch, back to the building on the other wire, into a telephone on the tip side (green wire). The neutral (other) side of the 110/120 AC went into the ring side (red lead) of the telephone. When the button was pushed, completed a 110/120 VAC circuit through the bell of the phone, making it ring for as long as someone held the button down. AC is not polarized, so could actually reverse the wires and would do the same thing. The point is that had to send AC out to one side of the "spring loaded momentary" switch on one wire, back to one side of the phone ringer on the other wire from the other side of the switch, and the other side of the AC had to go to the other side of the bell. Press the button, phone (bell) rang, then drove out there in a jeep and opened the gate. You could do that, but make sure that the AC source and cable are properly fused, because lightening just loves shallow cable. If you bury a cable, should be 24 or 22 Ga PIC (gel filled buried drop), should be a foot deep at least, and don't forget where buried it - and probably isn't code for civilians. In the army, we didn't care about code or regulations, we just did what had to be done, and kept our mouths shut.
|
|
|
