Check that your "loop" is working. Will also sniff out unwanted sources of 50 Hz fields from mains-powered equipment.

Apart from the beneficial effects that may be experienced, there is no quick way to ascertain whether the EPE Moodloop (Aug. '00) project is actually working, let alone check that it is working correctly. Various output arrangements can be used with it; the prototype used two loops constructed with a single length of 15-way ribbon cable which were connected in parallel to produce the required impedance of about 10 ohms.

If one of these loops were to fail, the field strength would obviously drop, but there would be no immediate indication of this to the user. Since plug and socket connections are used and the cable is fairly long and easy to damage this is quite a likely occurrence, so a means of checking the field strength is clearly needed.

This difficulty was spotted during the original "loop" design and consideration was given to the possibility of fitting some form of LED indication of the output current, but the various disadvantages of adding this to the circuit led to the idea being dropped at the time. However, some form of indication is definitely required, and this little project should fill that need.