Clare-Pendar Series S820
Contents
Overview
Clare-Pendar Series S820 is a tall reed switch series.
There are at least three different shell styles for these switches. One design (“Type 1”) is secured with screws placed down through the top of the shell, similar to Micro Switch Series KB. There are two recesses in the case at the top to make way for this, in opposite corners. In all discovered examples, however, no screws are fitted and the switches seem to be placed into a mounting plate solely for keycap alignment purposes. The oldest known examples are from 1971, which is also the date of the only known advertisement.
Type 1 was advertised in 1971 as being designed for plate cut-outs made with a standard ½″ punch, an arrangement intended to give good keycap alignment; minimum spacing was ⅝″. Lifetime had been tested at this point to 50 million operations. Options included 1 form A (SPST-NO) and 2 form A (DPST-NO) circuits, “snap in or cam-lock mounting” (neither being clarified further), lamp illumination (with 5, 12 and 28 V DC lamps available), 11° keystem angle and longer terminals to allow for wire wrapping. “Snap-in mounting” is likely to be closer in form to the arrangement seen with Micro Switch SN rather than keyboard plate mounting, as in keyboards the switches do not appear to ever attach to the mounting plate.
A second design (“Type 2”) has a profiled shell with no screw holes. Only one example of this has been seen, tentatively dated to 1976. This appears to be the design shown in the diagram within the 1986 catalogue entry (the photograph depicts a different design), where it is depicted with plate retention clips.
A third design (“Type 3”) is similar to the above, but has the plate retention clips in opposite corners. This is the design depicted in the photograph in the 1986 catalogue, which is shown below:
Top view of what appears to be S82010 J7 L1 (illuminated with tinned leads)
Side view; the moulding is a bit crude, with rough edges
Bottom showing “ASM MEXICO” markings and strange terminal numbering
This unidentifiable example almost fits the part number S82010 J7 L1 (J7 = illuminated, L1 = tinned leads). However, it is distinctly lower in force than the nominal weight of 2.5 oz suggests, which means that it could be a lower-weight type.
No advertisement or catalogue entry mentions an alternate action version of S820; it seems that this role was filled by S830.
Occurrences
- Unidentified keyboard: the switches are branded “CLARE/PENDAR”, and are part S820-10 from 1971 and 1972, with only the screw recesses clearly visible (“Type 1” switches); this keyboard may use a secretarial shift mechanism but it was not examined to that level of detail
- Unidentified keyboard: same keyboard as above (also from circa 1971), except with an alternate action S832-10B9 switch fitted to provide the extra Upper Case Alpha key, and the secretarial shift mechanism has been revealed
- CDC CC609D terminal: marked “S820” and branded “CLARE-PENDAR”, with screw holes; from the modification log on the unit, the switches are from no later than 1975 (“Type 1” switches)
- Unknown keyboard, possibly from week 44 1976; these switches are marked “CLARE-PENDAR” and “S820”, and lack screw holes (“Type 2” switches)
- “Vega 2200 Series” keypad, possibly from 1983 or later, with “Type 2” switches.
Documents
- Clare-Pendar S820 advertisement, Electromechanical Design, Vol. 15 No. 1-2, January-February 1971 (painfully extracted from the Internet Archive)
- S820 and S880 catalogue entry, September 1986 (front and back cover of the catalogue included; from Electro-Mech Components)
- S820 and S880 catalogue entry, older scan with L1 modification annotation (tinned leads) (from Electro-Mech Components)
The two catalogue entries were kindly scanned in by Electro-Mech Components, who took over part of the Pendar range.
See also
- S820 entry, Deskthority wiki (prior notes)