MODEL 78
1-1/4” Rectangular
Multiturn
Cermet Trimming
Potentiometer
ELECTRICAL
1
Standard Resistance Range, Ohms
Standard Resistance Tolerance
Input Voltage, Maximum
Slider Current, Maximum
Power Rating, Watts
End Resistance, Maximum
Actual Electrical Travel, Turns, Nominal
Dielectric Strength
Insulation Resistance, Minimum
Resolution
Contact Resistance Variation, Maximum
ENVIRONMENTAL
10 to 2Meg
±10% (<100 Ohms = ±20%)
300 Vdc or rms not to exceed power rating
100mA or within rated power, whichever is less
1.0 at 70°C derating to 0 at 125°C
2 Ohms
22
500 Vrms
1,000 Megohms
Essentially infinite
1% or 1 Ohm, whichever is greater
Seal
Temperature Coefficient, Maximum
Operating Temperature Range
Thermal Shock
Moisture Resistance
Shock, 6ms Sawtooth
Vibration
High Temperature Exposure
Rotational Life
Load Life at 1.0 Watts
Resistance to Solder Heat
MECHANICAL
85°C Fluorinert® (No Leaks)
±100ppm/°C
–55°C to +125°C
5 cycles, –55°C to +125°C (1%
∆RT,
1%
∆VR)
Ten 24 hour cycles (1%
∆RT,
IR 1,000 Megohms Min.)
100G’s (1%
∆RT,
1%
∆VR)
20G’s, 10 to 2,000 Hz (1%
∆RT,
1%
∆VR)
250 hours at 125°C (2%
∆RT,
2%
∆VR)
200 cycles (3%
∆RT)
1,000 hours at 70°C (2%
∆RT)
260°C for 10 sec. (1%
∆RT)
Mechanical Stops
Torque, Starting Maximum
Weight, Nominal
Fluorinert® is a registered trademark of 3M Company.
Specifications subject to change without notice.
Clutch Action, both ends
5oz.-in. (0.035 N-m)
.09 oz. (2.6 grams)
1-61
Model 78
SIDE ADJUSTMENT (Inch/mm)
Model 78P
Housing
Molded Plastic
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
.195
±
.005
4.953
±
0.127
Model No. &
Resistance
Value Marked
On This Surface
0.07
1.78
1.25
31.75
1.000
±
.005
25.400
±
0.127
.015
±
.003
0.127
±
0.076
2 Mounting Holes
.093
±
.005
I.D.
2.362
±
0.127
(1)
(2)
.125
±
.005
3.175
±
0.127
.105
2.667
.32
8.13
.135
.50
±
.03
(3) 3.429
12.70
±
0.76
.30
7.62
.260
±
.015
6.604
±
0.381
.70
17.78
3 Terminals Pins
Solderable
.028
±
.003
Dia.
0.711
±
0.076
.05
1.27
.10
2.54
Note: Model 78P dimensions applicable to all other models except as noted.
Model 78L
.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 78S
.187
±
.031
4.750
±
0.787
3 Terminals Pins
Solderable
.028
±
.003
Dia.
0.711
±
0.075
.05
±
.02
1.27
±
0.51
.10
±
.02
2.54
±
0.51
.156
±
.031
Dia.
3.962
±
0.787
(3 Places)
.70
±
.02
17.78
±
0.51
(1)
(2)
(3)
.30
±
.02
7.62
±
0.51
.26
±
.02
6.60
±
0.51
1-62
Model 78
PANEL MOUNT ADAPTER (Inch/mm)
1
Model 56BW
(Adapter Only)
Metal Bushing Mount
Brass-Nickel Plated
Mounting Surface
.125
±
.005
Dia. Hole
3.175
±
0.127
Use .22/5.613 Dia. Min. Mounting Hole
Lock Washer, Panel Nut, Sealing Washer
& Mounting Screws Provided
.312
±
.015
7.925
±
0.381
1.56
Max.
3.962
.437
Max.
11.100
Model 78LBW
(Adapter Pre-Assembled with Trimmer)
0.94
Max.
2.388
1.344
Max.
34.138
.250
±
.015
6.350
±
0.381
12-28 UNF-2A Thread
Model 78SBW
(Adapter Pre-Assembled with Trimmer)
0.94
Max.
2.388
1.344
Max.
34.138
.250
±
.015
6.350
±
0.381
(1)
(2)
(3)
12-28 UNF-2A Thread
.344
±
.031
8.738
±
0.787
1-63
Model 78
STANDARD RESISTANCE VALUES, OHMS
10
20
50
100
200
500
1K
2K
5K
10K
20K
25K
50K
100K
200K
250K
500K
1Meg
2Meg
PACKAGING
Standard:
Boxes
Capacity
=
25 Units
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
CIRCUIT DIAGRAM
NOTES
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
(2)
(1)
CW
(3)
INCH
mm
1-64
Model 78
PCB Design
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