1. Part Number UGN-3220S;
2. manufactured by Sprague Electric Company, Pembroke Road, Concord, NH.
3. An inexpensive pill-shaped permanent magnet was found to be quite satisfactory. It was 1 cm in diameter and 0.5 cm in thickness.
4. Manufactured by: Tektronix, Inc., P. O. Box 500, Beaverton, OR.
5. Manufactured by: Trans Era Corp., 3707 North Canyon Road, Provo, UT.