Cherry miniature open

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Cherry miniature open
Manufacturer Cherry
Switch type Clicky
Sense method Metal contact
Keycap mount None
Patents US 3056002 (1959)

Miniature open is a type of "mousetrap switch" from Cherry primarily intended for mains switching. Miniature open is a smaller version of the largely identical basic open type.


Series S30 standard miniature open switches are mains power switches rated for 10 A at 125 VAC, and 5 A at 250 VAC; as such, they cannot use gold crosspoint contacts, and instead use flat contacts. Series S31 comprises gold crosspoint variants intended for low-energy circuits.

Being lever action switches, both basic open and miniature open switches do not accept keycaps.


Multiple S30 types exist, including standard and narrow panel, multiple terminal types and multiple configurations. The part numbers according to the Cherry Switches & Keyboards Catalog C-73 are as follows:


Series: S30 — mains, S31 — low energy
Unknown (can be 0, 2 or 5)
Poles and throws: 0 — SPDT (changeover), 1 — SPST NO, 2 — SPST NC
Terminals: P — "PCB" (tubes, narrow type only), W — integral solder, T — flat solder, Z — quick connect

The codes above do not differentiate between wide and narrow base switches. "Integral solder" terminals are vertical with notches cut into either side; "quick connect" terminals have diagonal corners and no notches. "Flat solder" terminals protrude horizontally, with holes punched through them.

The default form of all miniature open switches is SPDT.

NOS switches with part number 01APBSW have been found. This type is a wide-base gold crosspoint switch with integral solder terminals. No evidence is given for the part number[1]

Gold crosspoint

The only gold crosspoint type listed in the C-73 catalogue is S31-20P, is specified as follows:

Characteristic Value
Operating force 7.5 oz (213 g) max
Rest position 0.533″ ‪(13.5 mm) max
Pretravel None
Operating point 0.378″ (‪9.6 mm)
Overtravel 0.045″ (1.14 mm) min
Movement differential 0.850″ (‪21.6 mm)


No confirmed examples exist. The Computer Communications 303 keyboard has switches virtually identical to catalogue depictions of Cherry Series S31 (with the only visible difference being a steeper actuator arm). Unlike S31-20P, the switches in this keyboard are simple SPST NO; one possible part number could be S31-21P.[1]