Raytheon: The Raysistor, an Optoelectronic Device in 1964

The Raysistor is a four terminal optoelectronic device which performs a variety of control functions, providing noise-free control of AC or DC signals over a wide dynamic range without transients or contact (or wiper) chatter. Since there are no moving parts, Raysistors are exceptionally rugged and have inherently long life in typical applications as variable resistors, solid state switches, relays and voltage or signal isolators. Operation of the Raysistor is on the principle of controlled light acting on a photo resistive element. No electrical or mechanical connections exists between the control and circuits. Chris V. from the US sent me a nice photo of a Selmer Varitone, saxophone amplifier were this element was used as a control element for modulating gain.

Case styles...

The Raysistor is made in different types/models with several case packages. Like the shape of a transistor  (TO-5), CK1115 or Tube version, CK1103 or Block version, CK1103P. But the most interesting  items are the CK1121-1124 series in the metal case version . This case style looks like a big TO-22, used in the earlier 2N35 from Sylvania etc. (end fifties). The datasheet is from 1964 so I suggest that most of these devices where produced around that period. Because of the unusual pinning of the case style, Raytheon supplied their Raysistors with their own sockets, see photo. Raytheon call their Raysistors Peak Limiter, because they were used in this kind of electronic  circuits.

Datasheet info..

I would like to thank Frank Philipse from Holland to with his great contribution of the datasheet information regarding these Raysistors. See his website for more info, especially with Tubes: http://www.tubedata.info/

Search on the internet..

If you search on the internet for more information you will find several of these "Peak Limiters". Some of them are in black metal cases like the CK2026 and CK2028S, blank metal devices I've fond where the CK2025 and the CK2052. This particular device is not yet described in  Wikipedia, all what could be found is the Photo resistor. This is a two pins device made of Cadmium Sulfide (CdS) and decreases with increasing incident light intensity. Maybe the Raysistor is protected by his patent, US3806802. A part of this patent has the following description: A Raysistor optical coupling control device connects an output from the detection system to a circuit driven by a signal based upon the primary signal.  More Raystistors like the CK2026S, CK2028S and CK2052 on the directory Raytheon --> Raysistors. I'm always interested in more information, please let me knows if you have some..

Technical spec's of the Raytheon Raysistor CK1122
Voltage=0-10V; Nominal current range=0-37mA; Resistance (on)=650-1000Ohms; Resistance (off)=10E9-5x10E7; Voltage(max)=200V; Power(max)=100mW; Typical switching time=30ms(on) 225ms(off);
Download the Raytheon Raysistor-series commercial specification from 1964
Raytheon Datasheet of the Raysistor series
Raytheon Datasheet of the ck1122