MODEL 78
1
1-1/4 Rectangular
Multiturn
Cermet Trimming
Potentiometer
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 70C derating to 0 at 125C
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 85C Fluorinert (No Leaks)
Temperature Coefficient, Maximum 100ppm/C
Operating Temperature Range 55C to +125C
Thermal Shock 5 cycles, 55C to +125C (1% RT, 1% VR)
Moisture Resistance Ten 24 hour cycles (1% RT, IR 1,000 Megohms Min.)
Shock, 6ms Sawtooth 100Gs (1% RT, 1% VR)
Vibration 20Gs, 10 to 2,000 Hz (1% RT, 1% VR)
High Temperature Exposure 250 hours at 125C (2% RT, 2% VR)
Rotational Life 200 cycles (3% RT)
Load Life at 1.0 Watts 1,000 hours at 70C (2% RT)
Resistance to Solder Heat 260C 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)
Fluorinert is a registered trademark of 3M Company.
Specifications subject to change without notice.
Model 78
1-61SIDE ADJUSTMENT (Inch/mm)
Model 78P
Circuit Diagram
Housing
Marked On This Surface
Molded Plastic
Metal
Adjustment Screw
.110/2.794 0.127 Dia. With .025/0.635
Model No. & 0.07
0.127 Wide X .031/0.787 0.127 Deep Slot
Resistance
1.78
Value Marked
1.25
.125 .005
On This Surface
.195 .005
31.75
3.175 0.127
4.953 0.127
1.000 .005
.105
25.400 0.127
2.667
.32
.015 .003
3 Terminals Pins
8.13
0.127 0.076
Solderable
.135
.50 .03
.028 .003
(1) (2) (3)
3.429 Dia.
2 Mounting Holes
12.70 0.76
0.711 0.076
.093 .005
I.D.
.05
2.362 0.127 .30
1.27
7.62
.10
.70 .260 .015
2.54
17.78 6.604 0.381
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)
.187 .031
Model 78S
4.750 0.787
3 Terminals Pins
Solderable
.028 .003
(1) (3)
(2)
Dia.
.156 .031
.30 .02 0.711 0.075
Dia.
3.962 0.787
7.62 0.51
.05 .02
(3 Places)
1.27 0.51
.26 .02
.70 .02
.10 .02
6.60 0.51
17.78 0.51 2.54 0.51
Model 78
1-62