1
1-61 Model 78
ELECTRICAL
Standard Resistance Range, Ohms 10 to 2Meg
Standard Resistance Tolerance ±10% (<100 Ohms = ±20%)
Input Voltage, Maximum 300 Vdc or rms not to exceed power rating
Slider Current, Maximum 100mA or within rated power, whichever is less
Power Rating, Watts 1.0 at 70°C derating to 0 at 125°C
End Resistance, Maximum 2 Ohms
Actual Electrical Travel, Turns, Nominal 22
Dielectric Strength 500 Vrms
Insulation Resistance, Minimum 1,000 Megohms
Resolution Essentially infinite
Contact Resistance Variation, Maximum 1% or 1 Ohm, whichever is greater
ENVIRONMENTAL
Seal 85°C Fluorinert® (No Leaks)
Temperature Coefficient, Maximum ±100ppm/°C
Operating Temperature Range –55°C to +125°C
Thermal Shock 5 cycles, –55°C to +125°C (1% ∆RT, 1% ∆VR)
Moisture Resistance Ten 24 hour cycles (1% ∆RT, IR 1,000 Megohms Min.)
Shock, 6ms Sawtooth 100G’s (1% ∆RT, 1% ∆VR)
Vibration 20G’s, 10 to 2,000 Hz (1% ∆RT, 1% ∆VR)
High Temperature Exposure 250 hours at 125°C (2% ∆RT, 2% ∆VR)
Rotational Life 200 cycles (3% ∆RT)
Load Life at 1.0 Watts 1,000 hours at 70°C (2% ∆RT)
Resistance to Solder Heat 260°C for 10 sec. (1% ∆RT)
MECHANICAL
Mechanical Stops Clutch Action, both ends
Torque, Starting Maximum 5oz.-in. (0.035 N-m)
Weight, Nominal .09 oz. (2.6 grams)
MODEL 78
1-1/4” Rectangular
Multiturn
Cermet Trimming
Potentiometer
Fluorinert® is a registered trademark of 3M Company.
Specifications subject to change without notice.
Model 78
1-62
Circuit Diagram
Marked On This Surface
Metal
Adjustment Screw
.110/2.794 ± 0.127 Dia. With .025/0.635
± 0.127 Wide X .031/0.787 ± 0.127 Deep Slot
0.07
1.78
Housing
Molded Plastic
.105
2.667
.32
8.13
.135
3.429
.30
7.62
.70
17.78
1.25
31.75
1.000 ± .005
25.400 ± 0.127
.125 ± .005
3.175 ± 0.127
.50 ± .03
12.70 ± 0.76
.195 ± .005
4.953 ± 0.127
3 Terminals Pins
Solderable
Dia.
.260 ± .015
6.604 ± 0.381
.015 ± .003
0.127 ± 0.076
.093 ± .005
2.362 ± 0.127 I.D.
2 Mounting Holes
Model No. &
Resistance
Value Marked
On This Surface
.10
2.54
.05
1.27
(1) (2) (3) .028 ± .003
0.711 ± 0.076
Model 78P
.062/1.575 Max.
Meniscus
3 Electrical Leads – 6/152 Min. Length
No. 30 AWG Teflon Insulated Stranded Wire
Yellow (1)
Red (2)
Green (3)
Model 78L
3 Terminals Pins
Solderable
Dia.
.30 ± .02
7.62 ± 0.51
.26 ± .02
6.60 ± 0.51
.70 ± .02
17.78 ± 0.51
.156 ± .031
3.962 ± 0.787
(3 Places)
.10 ± .02
2.54 ± 0.51
.05 ± .02
1.27 ± 0.51
.028 ± .003
0.711 ± 0.075
.187 ± .031
4.750 ± 0.787
(1)
Dia.
(2) (3)
Model 78S
SIDE ADJUSTMENT (Inch/mm)
Note: Model 78P dimensions applicable to all other models except as noted.
1
1-63 Model 78
(1) (2) (3) .344 ± .031
8.738 ± 0.787
.250 ± .015
6.350 ± 0.381
1.344
34.138
12-28 UNF-2A Thread
Max.
0.94
2.388 Max.
Model 78SBW (Adapter Pre-Assembled with Trimmer)
.250 ± .015
6.350 ± 0.381
1.344
34.138
12-28 UNF-2A Thread
Max.
0.94
2.388 Max.
Model 78LBW (Adapter Pre-Assembled with Trimmer)
.125 ± .005
3.175 ± 0.127
Metal Bushing Mount
Brass-Nickel Plated
Use .22/5.613 Dia. Min. Mounting Hole
Lock Washer, Panel Nut, Sealing Washer
& Mounting Screws Provided
Mounting Surface
Dia. Hole
1.56
3.962
.312 ± .015
7.925 ± 0.381
Max.
.437
11.100Max.
Model 56BW (Adapter Only)
PANEL MOUNT ADAPTER (Inch/mm)
1-64 Model 78
CIRCUIT DIAGRAM
(1)
(2)
(3)
CW
NOTES
mm
INCH
Metric equivalents, based on 1 inch = 25.4mm are
rounded to the same number of significant figures
as in the original English units and are provided for
general information only.
Tolerances unless otherwise specified:
Linear = ± .01 inches (.25mm)
Angular = ± 2 degrees
ORDERING INFORMATION
78 P BW R 10K LF
Model Series
Pin Style
RoHS Compliant Code - optional
Resistance Value
Resistance Prefix
Optional Panel
Mount Adapter
Note: Use ‘56BW’ to order panel mount adapter without trimmer
PACKAGING
Standard: Boxes
Capacity = 25 Units
STANDARD RESISTANCE VALUES, OHMS
10 200 5K 50K 500K
20 500 10K 100K 1Meg
50 1K 20K 200K 2Meg
100 2K 25K 250K
