1A Whistle
By Paul Wills, ; posted February 21, 2003; hits 4109
 |
| This is used to produce a 1000/20 Hz signal in order to ring the end of a composited telephone trunk. |
By Paul Wills, ; posted February 21, 2003; hits 4109
|
| This is used to produce a 1000/20 Hz signal in order to ring the end of a composited telephone trunk. |