Kingtronics Blog

Selection Criteria
The initial considerations for trimmer type selection are:
A. Resolution of adjustment
B. Setability and time to set
C. Physical and environmental conditions
D. Stability of setting required
E. Circuit packaging requirements

D. Stability of Setting
It is highly desirable that once the trimmer has been set, it should remain at that setting independent of time, operating temperature changes, vibration, shock and humidity. This property of stability is largely a factor of the compatibility of the materials at the moving contact interface and the thermal matching of the elements of the trimmer structure. BI uses noble metals in both the wire brush contact and the cermet element. These materials are relatively soft, highly compatible and provide an excellent, low resistance, non-corroding interface. The contact drive structure and materials are chosen for their stability and compatibility. The high contact forces utilized at the brush/element interface reduce susceptibility to shock and vibration.

The circuit designer can contribute significantly to short term operating and long term stability by mounting the trimmer away from high thermal gradients, hot spots and sources of excessive vibration.

E. Circuit Packaging
BI manufactures trimmers in a variety of package styles and sizes. The chances are excellent that stock models are locally available that will fit your requirements. Models include both pin style and surface mount single and multiturn configurations. Special electrical and mechanical features are available for specific customer applications. Call your local representative or the factory direct for information on special packaging.

Selection Criteria
The initial considerations for trimmer type selection are:
A. Resolution of adjustment
B. Setability and time to set
C. Physical and environmental conditions
D. Stability of setting required
E. Circuit packaging requirements 

C. Physical and Environmental Issues

1. Physical considerations in trimmer selection
• Case style desired
• Top or side adjust
• Pin style required
• Mechanical support required
• Board height requirements

2. Assembly process considerations
BI offers a variety of trimmer models that are sealed to help protect against moisture and board washing processes.
•Open vs. Sealed
• Max time/temperature exposure 

3. Environmental operating considerations
• Operating temperature range
• Resistance temperature coefficient
• Vibration and shock tolerance 

4. Human operating conditions When you complete your design, be careful to consider the tortures that clever human beings with a screwdriver in hand can impose on trimmers. For example, while a trimmer configuration mounted on edge might be a board space saver, a trimmer that mounts flat on the board may be more resistant to abuse by a heavy handed technician making adjustments through a hole in the chassis.

Selection Criteria
The initial considerations for trimmer type selection are:
A. Resolution of adjustment
B. Setability and time to set
C. Physical and environmental conditions
D. Stability of setting required
E. Circuit packaging requirements

B. Setability and Time to Set
The enemies of setability are poor resolution, mechanical backlash and high CRV. BI has addressed these problems in the design of trimmer models. BI’s smooth cermet materials, precious metal split brush contacts and teflon rotors work together to provide outstanding setability.

“Time to set” tests show the following:

II. Selection Criteria
The initial considerations for trimmer type selection are:
A. Resolution of adjustment
B. Setability and time to set
C. Physical and environmental conditions
D. Stability of setting required
E. Circuit packaging requirements

A. Resolution of Adjustment
1. Multiturns
• Multiturns provide better resolution than single turns. Models with a longer element exhibit better resolution than those with a short element. Typical multiturn shaft revolutions range from 15 to 20 turns for end to end travel.
• The contact design and stability are important considerations in achieving high resolution. The contact area must be small and the contact must move smoothly in order to provide high resolution. A noisy contact will make accurate setting very difficult.
• All trimmers utilize smooth cermet materials, precious metal wire brush contacts and backlash-free wiper designs that ensure high resolution setability.
• Reference multiturn models:
Square multiturns - 44, 64, 66, 67, 68
Rectangular multiturns 78, 89

2. Single Turns
• Single turn resolution for models with a longer cermet element (larger diameter) is quite respectable. This is especially true with wire brush contacts and smooth cermet films.
• Reference single turn models:
Small diameter - 24, 25, 62, 82
Larger diameter - 72, 91, 93

3. Surface Mount Models
• Single turn - 21, 23, 83
• Multiturn - 44, 84

A trimmer can be used as potentiometer or rheostat. A potentiometer is a three terminal device typically used to vary voltage. In potentiometric configurations, the wiper terminal is lightly loaded so that wiper current is generally small.

A rheostat is a two terminal device typically used to control current. Wiper current is generally larger in rheostat circuits.

I. Types of Applications
The majority of applications for trimmers occur in electronic circuits. 
Typical uses are in the following devices:
A. Amplifiers
B. Timing circuits
C. Voltage and current regulators
D. Voltage and frequency converters

WELDABILITY:
The ability of materials to be welded together under specified conditions.

TERMINAL STRENGTH:
The ability of the terminals to withstand specified mechanical stresses without sustaining damage that would affect utility of the terminals or operation of the trimming potentiometer.

IMMERSION SEALED:
The ability of the unit to withstand submersion in acceptable cleaning solutions used in normal soldering processes without performance degradation under specific environmental conditions.

TORQUE

STARTING (OPERATING) TORQUE:
The maximum moment in the clockwise and counterclockwise directions required to initiate shaft adjustment anywhere in the mechanical travel.

STOP TORQUE:
The maximum static moment that can be applied to adjustment shaft at each mechanical stop for a specified period of time without loss of continuity or mechanical damage affecting operational characteristics.

SOLDERABILITY:
The ability of the terminals to accept a uniform coating of solder under specified conditions.

Kingtronics offers full range of Trimming Potentiometers with our own trademark "Kt" since 1990.
We gain high reputation by our trimpots superior quality and competitive price. We are proud that Kingtronics Trimpot are well-known in the overseas market.

In Jan 2016, we prepared all the key raw materials of Trimming Potentiometers and then handed over to SGS laboratory.
After 1 week testing , we got the positive reply of our potentiometers from SGS company.  Now we would like to share this good news with our Kingtronics faithful customer.
Kingtronics Trimming Potentiometer is your first chosie, and Kingtronics is your best partner.

More details about our RoHS 2.0 Report, please visit below link:
http://www.kingtronics.com/pdf/Trimming-potentiometer-RoHS.pdf

ROTATIONAL LIFE:
The number of cycles obtainable under specific operating conditions while remaining within specified allowable degradation. A cycle is defined as one complete traversal of the wiper over the resistive element in both directions.

LOAD LIFE:
The number of hours at which a device may dissipate rated power under specified operating conditions while remaining within specified allowable degradations.

ADJUSTABILITY:
Defines the precision with which the output of a device can be set to the desired value.

ADJUSTABILITY (OUTPUT RESISTANCE):
The precision with which the output resistance of a device can be set to the desired value.

ADJUSTABILITY (OUTPUT VOLTAGE RATIO):
The precision with which the output voltage ratio of a device can be set to the desired value.

CONTINUITY:
Continuity is the maintenance of continuous electrical contact between the wiper and both end terminals of the resistive element.

SETTING STABILITY:
The amount of change in the output voltage, without readjustment, expressed as a percentage of the total applied voltage.

DIELECTRIC STRENGTH:
The ability to withstand the application of a specified potential of a given characteristic, between the terminals and all other external conducting member such as shaft, housing and mounting hardware without exceeding a specified leakage current value.

INSULATION RESISTANCE:
The resistance to a specified dc voltage impressed between the terminals and all other external conducting members such as shaft, housing and mounting hardware.

POWER RATING:
The maximum power that a trimming potentiometer can dissipate across the total resistive element under specified conditions while meeting specified performance requirements.