Always begin use at a reduced sensitivity level; this device is designed to work “into-the-noise”, so expect chatter at high sensitivity. 2) Do not use indoors. This detector is for outdoor use only. Many household appliances emit electromagnetic energy, which can interfere with the detector. If conducting an indoor demonstration, turn the sensitivity down and keep the search coil away from appliances such as computers, televisions and microwave ovens. If your detector beeps erratically, turn of