NT IA PL M ■ *R oH S CO Features ■ ■ ■ 7/8 ” (22 mm) diameter single-turn conductive plastic Bushing mount Excellent resolution High rotational life – ball bearing shaft support ■ Non-standard features and specifications available 6638 - Precision Potentiometer Electrical Characteristics1 Standard Resistance Range....................................................................................1 K to 100 K ohms Total Resistance Tolerance .........................................................................................................±10 % Independent Linearity ...................................................................................................................±1 % Effective Electrical Angle .......................................................................................................340 ° ±3 ° End Voltage .................................................................................................................0.5 % maximum Output Smoothness ....................................................................................................0.1 % maximum Dielectric Withstanding Voltage (MIL-STD-202, Method 301) Sea Level .............................................................................................................750 VAC minimum Power Rating (Voltage Limited By Power Dissipation or 300 VAC, Whichever is Less) +70 °C......................................................................................................................................1 watt +125 °C....................................................................................................................................0 watt Insulation Resistance (500 VDC)..................................................................1,000 megohms minimum Resolution..................................................................................................................Essentially infinite Environmental Characteristics1 Operating Temperature Range...................................................................................+1 °C to +125 °C Storage Temperature Range.....................................................................................-65 °C to +125 °C Temperature Coefficient Over Storage Temperature Range ...........................±500 ppm/°C maximum Vibration .........................................................................................................................................15 G Wiper Bounce ...........................................................................................0.1 millisecond maximum Total Resistance Shift ..............................................................................................±5 % maximum Voltage Ratio Shift ................................................................................................±0.5 % maximum Shock .............................................................................................................................................50 G Wiper Bounce ...........................................................................................0.1 millisecond maximum Total Resistance Shift ..............................................................................................±5 % maximum Voltage Ratio Shift ................................................................................................±0.5 % maximum Load Life .................................................................................................................1,000 hours, 1 watt Total Resistance Shift ............................................................................................±10 % maximum Rotational Life (No Load) .........................................................................20,000,000 shaft revolutions Total Resistance Shift ............................................................................................±10 % maximum Moisture Resistance (MIL-STD-202, Method 106) Total Resistance Shift ............................................................................................±10 % maximum IP Rating ........................................................................................................................................IP 40 Product Dimensions 6638 7/8 " (22 mm) DIA. 1 At room ambient: +25 °C nominal and 50 % relative humidity, except as noted. CW 3 1.57 13.64 ± .38 (.062) (.537 ± .015) 22.23 (7/8) DIA. 1 45 ° ± 5 ° 7.14 + .00/- .05 DIA. (.281+.000/-.002) 1/4"-32 UNEF-THD 3.170 + .000/-.008 DIA. (.1248+.0000/.0003) .25 45 ° ± 5° X (.010) CHAMFER 9.53 (3/8) 3.18 (1/8) 22.23 (7/8) .38 (.015) SHAFT SLOT .81 .81 (.032) WIDE X (.032) DEEP TOLERANCES: EXCEPT WHERE NOTED .51 .127 DECIMALS: .XX ± .XXX ± (.02), (.005) FRACTIONS: ±1/64 MM DIMENSIONS: (IN.) Mechanical Characteristics1 Mechanical Angle ................................................................................................................Continuous Torque (Starting & Running) ............................................................0.18 N-cm (0.25 oz.-in.) maximum Mounting.............................................................................170-200 N-cm (15-18 lb.-in.) maximum Shaft Runout................................................................................................0.025 mm (0.001 in.) T.I.R. Shaft End Play ...............................................................................................0.13 mm (0.005 in.) T.I.R. Shaft Radial Play ...........................................................................................0.08 mm (0.003 in.) T.I.R. Backlash ........................................................................................................................0.1 º maximum Weight ..........................................................................................................................................18 gm Terminals.......................................................................................................................Rear turret type Soldering Condition....................Recommended hand soldering using Sn95/Ag5 no clean solder, 0.025 ” wire diameter. Maximum temperature 399 °C (750 °F) for 3 seconds. No wash process to be used with no clean flux. Marking ................................Manufacturer’s name and part number, resistance value and tolerance, linearity tolerance, wiring diagram, and date code Ganging (Multiple Section Potentiometers) .................................................................1 cup maximum Hardware ...................................................One lockwasher (H-37-1) and one mounting unit (H-38-1) is shipped with each potentiometer. 2 5.08 R (.20) 2 CCW WIPER 3 1 CW CLOCKWISE Recommended Part Numbers Part Numbers Resistance (Ω) 6638S-1-102 6638S-1-502 6638S-1-103 1,000 5,000 10,000 BOLDFACE LISTINGS ARE IN STOCK AND READILY AVAILABLE THROUGH DISTRIBUTION. FOR OTHER OPTIONS CONSULT FACTORY. REV. 06/06 *RoHS Directive 2002/95/EC Jan 27 2003 including Annex Specifications are subject to change without notice. Customers should verify actual device performance in their specific applications.