Troubleshoot ground loops fast


...and without disconnecting anything!

After investing substantial time and money putting together an electronic instrument system that is supposed to measure an important signal,  what you get is corrupted by a ground loop. Chasing down such a ground loop has traditionally been a frustrating experience like trying to find a needle in a haystack  - you could spend hours or days searching without success.

No longer! The Loop SloothTM (patent pending) enables quick determination of which cable or cables are involved in a ground loop without disconnecting anything. What used to take hours or days of frustration now takes minutes!

The Loop SloothTM consists of two battery-powered modules, an Exciter and a Detector. The Exciter uses a proprietary clamp-on transformer to induce a high-frequency current in a ground loop -- if the loop exists  -- while the clamp-on Detector detects the AC magnetic field associated with this current. Because the Detector is tuned to the same frequency as the Exciter,  the Detector responds only to the signal injected by the Exciter. Scroll through the three photos below to see how the Loop SloothTM is used to find a simple ground loop.

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INSTRUCTION MANUAL

Detailed Technical Reference: P. M. Bellan, Simple system for locating ground loops, Review of Scientific Instruments Volume 78, Article Number 065104 (2007)

Figure 1
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Figure 1: Which cable is causing a ground loop? The Loop SloothTM (patent pending) makes it possible to find out fast without disconnecting anything!
Figure 2
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Figure 2: First, the Exciter and Detector are both linked to the power cord of one of the instruments.  If the Detector red light illuminates as shown in the figure, the instrument power cord is part of a ground loop. The Detector meter gives an indication of the severity of the ground loop.

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Figure 3:  Next, with the Exciter remaining linked to the instrument power cord, the Detector is linked around a suspect cable. If the Detector red light illuminates, the linked cable is part of the ground loop! If the red light does not illuminate, the linked cable is not part of the ground loop. The meter shows whether all the ground loop current flows in the linked cable or whether the current in the power cord has become subdivided to flow through two or more cables.