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Controls Research Corp

Contents

Overview

Controls Research Corporation (CRC) is a very poorly-understood company. Examples of their keyboards and switches are rare almost to the point of nonexistent. One keyboard example has been found, as has one calculator example. Additionally, a bare keypad has been found.

Keyboards

Mark II

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 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.

Switches

CRC 02

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.

Bi-Pac

Bi-Pac is a mechanical switch type whose switch contacts are a pair of concentric coil springs. The wider outer spring has the top end formed into a horizontal bar, and as it is pressed down by the plunger, it makes contact with the top of the inner spring. The springs form the solder terminals. Overtravel is achieved when the inner spring is also compressed.

The switches are formed into blocks that are almost identical in layout to Key Tronic and Maxi-Switch switches. The switch blocks and inner workings are illustrated in Electronic Design magazine in 1972 [ED1972-FOK], under the name “Bi-Pac”.

British patent 1345831 filed in May 1972 covers the switch. Priority was given to a US patent application, but this patent cannot be found.

Examples

There is only one confirmed example:

In [ED1972-FOK] a complete calculator keypad is shown, that uses Bi-Pac switches. A very similar CRC keypad was used in the Summit 3114, with the main difference being a slightly different key arrangement.

Reed

In [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.

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Top
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Top, with keycaps removed to reveal the switches
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Top, with plunger assembly removed to reveal the reed capsules
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Left side, with similar markings to those on Hi-Tek and Stackpole assemblies
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Left side, with plunger assembly removed to reveal the reed capsules
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Reed capsule detail
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Plunger assembly, secured to the PCB with screws
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Plunger assembly base
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Plunger assembly opened
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Plunger assembly components, including annular magnet
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PCB, showing curious arrangement of tracks and connection positions