Whether a projector is religious or not, prayer is a useful countermeasure. Pray to whatever is believed in most, with whatever words are preferred, silently or aloud. If you are not religious and have trouble deciding on who or what to pray to, angels are a decidedly good choice. Please take my word for it, angels are very real high-level spiritual beings and I have come across them many times in my life, both in and out of my body. Ask sincerely and reverently for their protection, help and direct intervention with any negative interference problems. All religious or spiritual benefits aside, sincere prayer also cultivates a positive mental attitude which can be of enormous help in any stressful or unnerving situation. Memorizing formal prayers, like The Lord's Prayer and 21st Psalm, Psalm 31 and 35, is also an excellent countermeasure. Memorization (highly recommended for serious entity problems) places material 'inside' the mind. This has an internal repellant affect on negative entities.
Religious icons and pictures can also be very beneficial and make for excellent passive wards. These tend to lift the energy tone of any room or house, and this encourages a positive and harmonious atmosphere. Many types of astral wildlife also appear to find religious paraphernalia offensive and will not enter an area containing these, especially if these items have been properly blessed. If you care about these items and believe in what they represent, then their effectiveness will also be increased accordingly.