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Cherry reed switches

Contents

Overview

Cherry filed a patent for a tactile reed switch in July 1970. US patent 3644855 was granted in February 1972. It seems that this switch was only marketed for a brief time: it was included in Cherry marketing literature in 1971, and no longer mentioned by 1973.

The design given in the patent achieves the tactile feel by way of magnetic separation. A metal disc embedded into the switch attracts the magnet and stops it moving. After a spring above the magnet is sufficiently compressed by the operator via the plunger, the force within that spring becomes great enough to force the magnet off the disc. There is a separate main return spring placed under the magnet. The illustrations in Cherry’s literature do not depict this arrangement, and there is no mention of tactile feedback.

The reed switches are tall, with a distance of 1.12″ (28.4 mm) from the top of the PCB to the top of the plate, and 0.06″ (1.5 mm) of the shell above the plate.

Models

Cherry reed switches used the old model numbering system; only the following models are known:

Model Type
201-0100 SPST-NO
202-0100 DPST-NO

Specifications

Operating force 2.5±0.5 oz
Pretravel 332±132″ (also given as 0.093±0.031″; approx. 2.4±0.8 mm)
Total travel 316″ maximum (approx. 0.188″, or 4.8 mm)
DC resistive load 7 W maximum
AC resistive load 12 VA maximum
Current 0.25 A maximum
Voltage 28 V maximum
Bounce time 1 ms maximum
Initial contact resistance 250 mΩ maximum
Rated lifetime 10 million cycles minimum

Documentation

Both documents were scanned and made available by Bitsavers under Cherry components.