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 Product Dimensions 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 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 Manual Soldering................................96.5Sn/3.0Ag/0.5Cu solid wire or no-clean rosin cored wire 370 °C (700 °F) max. for 3 seconds Wave Soldering ........................................................96.5Sn/3.0Ag/0.5Cu solder with no-clean flux 260 °C (500 °F) max. for 5 seconds Wash processes ..................................................................................................Not recommended 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. 10/08 *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.