The Noisephone II is a solid state amplified listening device. It is designed to be used in conjunction with capacitive discharge impulse fault locators (thumpers) to help in precisely locating underground cable faults. The lightweight amplifier is hung around the operator’s neck and the rugged pickup head is tethered to it by a 5 foot braided nylon sheath containing the small connecting cable. A single on-off/volume control is operates the unit. The interal active volume limiter reduces the maximum volume to a comfortable level during loud transients such as dropping the pickup head. This allows the volume control to be left as a high level while lifting the pickup head by its cable, moving it, and putting it down to listen.
A sharply-tuned electronic filter virtually eliminates traffic noise allowing use adjacent to heavily traveled roadways. It is powered by six AA alkaline batteries. The pickup head also ignores rustling grass and rain. Three removable spikes are provided to install in the pickup head when using the unit on grass.
An internal magnetic impulse indicator (electrically identical to our MI-88) assists in locating the fault by indicating (1) that the thumper is still running: (2) that the user is walking the proper cable route; and (3) exactly when the thump occurs, so the user can be listening carefully at that instant.