The Photoreed-A New Versatile Frequency-Sensitive Control Element

The photoreed performs the functions of resonant reed relays and tuning-fork filters or oscillators. The photoreed evolved from combining resonant reed and photoelectric principles, i.e., the action of light on a suitable photosensor to regulate the current through the photosensor and its load circuit. The photosensor is exposed to the light when the reed, acting as a shutter, vibrates. No electrical contacts are required. The design criteria and performance data of the photoreed are discussed for each circuit function. The photoreed has superior performance, flexibility and versatility when compared with conventional resonant reed relays.