About Sondes

Benefits of a Frequency Locator

Sonde 512Hz512 Hz sondes, also referred to as “moles” or “beacons”, work with any Schonstedt pipe & cable locator.  Sondes benefit a variety of industry applications. In water & sewer, they can help pin-point blockages or pipeline defects when used with video inspection systems. You can trace a path and determine the depth of a non-metal pipe such as HDPE, PVC, transcite or clay tile. In cable applications they can be used to trace empty fiber-duct or adjacent conduit runs and stop at unmarked underground vaults or splice boxes. The depth accuracy of a sonde’s position can help reduce excavation costs and time. Depending on frequency, a self-contained battery powered sonde can be detected as deep as 15 ft.



Sonde Video Frequency Locator

Video: Locating a Sonde

Pipe & Cable Locators that use Sondes are helpful for the following:

  • Water & Sewer – Detect position of blockages and locate pipe defects, transition points or other areas of interest within the pipeline infrastructure. Locate non-metal pipes via an open access point or clean-out.
  • Telecom – Path of empty fiber-duct
  • Electrical – Path of empty conduit runs
  • Plumbing – Locate the path or blockage of a poly pipe to septic tank or field
  • Industrial – Pipeline process inspection work
  • Gas – Pipeline integrity project work; Pipeline pig tracking (w/ 512 Hz transmitted sonde)


Sondes come with fittings and can be affixed to any duct rodder, plumber’s snake, fish tape, camera assembly or other insertion device (adapters may be required by user).


Specifications Chart

Sonde 512 Large
Sonde: Large


512 Hz

Size (inches)

1.53" dia x 4.13"


1 - AA

Battery Life

6-8 hours continuous use @ 70°F (21°C)


M10 (10mm) Thread

Depth Range

14 - 16 Ft max
soil type dependent