Controls Research Corp
Controls Research Corporation (CRC) is a very poorly-understood company. Examples of their keyboards and switches are extremely rare. Two keyboard examples have been found, as has one calculator example. Additionally, a bare keypad has been found.
The CRC Mark II keyboard was a bespoke keyboard arrangement built around CRC 02 discrete snap-action dry reed switches.
The Mark II keyboards brochure (see Documentation, below) indicates that there are patents pending, but no US patents for Controls Research Corporation seem to have been digitised. Sadly the brochure gives no indication of its age.
CRC 02 is a tall discrete reed switch module offered with CRC’s Mark II keyboards. These switches were advertised as having “magnetic snap action”. The design is fairly tall, measuring 2.025 inches from the centre of the switch base to the top of the keycap. The top of the switch body is 1.25 inches from the PCB, measured from the centre of the base. The base of the switch is angled to 10° to provide a stepped profile when the PCB itself is angled likewise. Switches are secured to the PCB using a pair of 2-56 machine screws.
The switch is illustrated in the brochure as follows:
The switch specifications are as follows:
|Travel||0.156″ (around 3.96 mm)|
|Return force||1 oz (around 28 g)|
|Snap force||3 oz (85 g)|
|Contact life||1 million cycles|
|Bounce time||0.5 ms|
|Voltage||40 V maximum|
|Current||50 mA maximum|
The switch diagram has the keycap labelled “I.B.M. KEYTOP”, which is shown as truncated in the top view, and cuboid in the side view. The keycap mount is not illustrated, but chances are it will be flat stem mounting.
See the BI-PAC page for more details.
In Electronic Design magazine in 1972 [ED1972-FOK], it was mentioned that CRC also offered reed switches. No details on these were given. Reed switch modules matching the style of the BI-PAC modules can be seen in an unidentified CRC keypad, shown below, with PCB part number 13C0117200-4. The plunger guide shafts of these modules seem to be considerably taller than those of BI-PAC. The production date is not clearly marked, but the PCB is stamped “34 73” which may be the week and year. The photos below were provided by Deepak Kandepet, who made the discovery.
US patent 3965399 “Pushbutton capacitive transducer”, filed in March 1974, depicts a capacitive switch with an internal buckling rubber sleeve (a rare example of a non-Topre capacitive switch with the return force device on the inside). The patent was filed by Jr Frank A Walker and John B Shevlin, rather than Controls Research (the applicants are listed as “both c/o Controls Research Corporation”, so it’s not entirely certain that this would have been produced or sold as a Controls Research design. In any case, such a keyboard has yet to be observed.
The switch housing has an angled base, for use on a sloping PCB, as with the CRC 02 design. The capacitive element is a foam pad. The purpose of the foam pad is two-fold: it provides overtravel, and in conjunction with the flexible conductive film, its compressibility ensures that the entirety of the conductive film presses down evenly on the PCB to ensure consistent capacitance.