|Serial number||NMI-37"NMI" can not be assigned to a declared number type with value -37.|
- 37. NML Pendulum Cone Detector -Dr. Eugen Merten Shell (circa 1950) Cone assembly in center pivots at bottom and, at top, has a wire wound coil which moves horizontally through a permanent magnet Stamped on top of the case is a triangle containing the letter L at top and the numbers 652 at bottom. Below the triangle is stamped MADE IN USA. A assembled cutaway unit is the basic unit removed from case. A horseshoe style magnet, mechanical magnification of motion, long moment arm, (shaped like a cone). Single leaf spring, small moving coil, adjustable resonant frequency, large voltage output, 7.4lbs.