Pushbutton Switches Specifications are subject to change. Please refer to the current datasheet on www.grayhill.com for the most current published specifications for this product. Butt Contact Pushbutton Switches SerieS 38Bt and 38BH Sub-Miniature Horizontal PC Mount FeatureS Drop-In Replacement for Industr y Standard Sealed Plunger Option Pr inted Circuit Board Mount SPST and SPDT, Momentar y Contact diMenSiOnS in inches (and millimeters) 38Bt .125 .215 .162 C .320 (8,13) L (3,18) (5,46) (4,11) PC Mounting .025 .043 (1,09) .249 .200 (0,64) C .130 DIA. TYP. (6,32) L (5,08) (3,30) .100 (2,54) .200 .125 DIA. (5,08) (3,18) .180 (4,57) .030 .165 (4,19) .030 (0,76) TYP020 .200 DIA. (0,76) (0,51) .200 .015 (0,38) TYP. (5,08) TYP200 (5,08) TYP. (5,08) SPSt 38BH .320 PC Mounting C DIM. L .162 (8.13) .025 (4.11) (0.64) .043 (1.09) DIA. TYP100 .200 .249 (2.54) C .130 L (5.08) (6.32) TYP. (3.30) 1 2 3 .180 .125 TERMINAL .100 .030 (4.57) (3.18) IDENT- (2.54) .030 (0.76) DIA020 DIA. IFICATION (0.76) .165 TYP200 .200 (0.51) TYP. (4.19) (5.08) (5.08) TYP200 .200 (5.08) .015 (5.08) SPdt (0.38) TYP. Unless otherwise indicated, tolerances are .010 (0,25) SPeCiFiCatiOnS rating Criteria Materials and Finishes Base and Cover: Ther moplastic (UL 94V-0) Operating Life: 80,000 make-and-break cycles insulation resistance: 1 0 0 0 m e g a o h m s at full load min. Plunger: Ther moplastic (UL 94V-0), (S versions Contact rating (resistive load): Voltage Breakdown: 1000 Vr ms minimum at include an inter nal o-r ing seal) t erminals: Copper alloy, gold or silver plate (as Gold Contacts: 0.4 VA maximum at 20 Vac or sea level Vdc maximum Operating t emperature: -30C. to +85C. specified) over nickel plate Spring: Plated Music Wire Silver Contacts : 1.0 Amp maximum at 120 Vac Solderability: Pe r M I L - S T D - 2 0 2 F, M e t h o d or 28 Vdc 208D, or EIA RS-186E Method 9 (1 hour steam Contact System: Copper alloy, gold or silver Contact resistance: Below 20 milliohms typical aging) plate (as specified) over nickel plate Switch Support: Brass, tin-plated initial at 2-4 Vdc, 100 mA CirCuitry OrderinG inFOrMatiOn Series: 38BT = SPST, Momentar y, Thr u Hole Series: 38BH = SPDT, Momentar y, Thr u Hole SPStn.O. dimension a: 0 = 0.020 4 = 0.215 38BX-4-H-3-n SPSt n.O. Seal: S = O-Ring Seal, N = No Seal Contact Material: 1 = Solder Dip over Gold N.C. 2 = Solder Dip over Silver TERM. 1 COMM 3 = Gold - RoHS Compliant TERM. 2 N.O. 4 = Silver - RoHS Compliant TERM. 3 Orientation: H = Hor izontal to PCB SPdtn.O. Grayhill, Inc. 561 Hillgrove Avenue LaGrange, Illinois 60525-5997 USA Phone: 708-354-1040 Fax: 708-354-2820 www.grayhill.comSpecifications are subject to change. Please refer to the current datasheet on www.grayhill.com for the most current published specifications for this product. Pushbutton Engineering Information Pushbutton switches are selected not only the switch. The rapid rate of make and break Butt Contacts have less wear than wiping by their ratings, but also by their contact contacts and therefore, have a longer life. means that these switches are appropriate for type. While nearly all rotary switches and They are also smaller. Butt contacts are not high current loads. They usually have a slight DIP switches have wiping contacts, pushbut- wiping action and contact surfaces made of self-cleaning, so their contact resistance can ton switches may have either wiping or butt vary from operation to operation. precious metals to minimize their disadvan- contacts (see internal views below). tages. Snap Action switches are basically butt con- Wiping Contacts are self-cleaning and usually tact switches with a spring mechanism which provide a low resistance in circuits where provides the make and break. The mecha- contact resistance is critical. However, the nism controls both the operating point and wiping action creates mechanical wear and the rate of operation, but adds to the wear of conductive wear products. Internal Views of Pushbutton Switches Wiping Contact Snap Action Butt Contact ACTUATOR ACTUATOR ACTUATOR BUSHING BUSHING BUSHING OVERSPRING SHORTING INTERNAL FIXED BUTTON BAR CONTACTS SHORTING RETURN MOVABLE BAR SPRING CONTACT RETURN FIXED CONTACTS SPRING FIXED CONTACTS Switch Terminology Actuator: The part of the switch to which an external force is applied to operate the switch. Make-Before-Break Switch (MBB): A double N.O., Normally Open: Switch in which the circuit is open without actuation (with actuator in throw switch in which the contacts makes con- Alternate Action (Push-Push) Switch: A thenorma position). nection with the second circuit before switch in which the operable position is breaking contact with the first also called maintained after the first actuation, and then Overtravel: The distance or angle between the shorting switch. disengaged with the second operation. operating position and the extreme position to which the actuator may be moved. Maintained Contact Switch: A switch in which Break-Before-Make Switch (BBM): A the actuator remains in a position until it is actu- double throw switch in which the moving ated to another position where it also remains Pole: An electrically isolated circuit within a contact breaks the connection with the first switch a common terminal and all the selected until actuated. Example: Push-Pull Switch. circuit before terminals to which it connects. making contact with the second also called Momentary Contact Switch: A switch in non-shorting switch. Pretravel: The distance or angle through which which the shorting bar returns from its operated position to its normal or free position when the the actuator moves from its free position to its Double Throw Switch: A switch which has electrical operating position. actuating force is removed. a normally open as well as a normally closed circuit per pole. Single Throw Switch: A switch which has Operating Position or Point: The position of only one normally open or one normally closed the actuator when the desired electrical action Joystick Action Switch: (From Joystick, (make or break of contact) occurs. circuit per pole. the control for an airplane). A lever switch which operates with momentary action in 4 N.C., Normally Closed: Switch in which the Throw: See Single Throw and Double Throw. directions, and is disengaged in the upright circuit is closed without actuation (with actuator position. in thenorma position). www.grayhill.com