Kingtronics Blog

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.

How fast time flies. Here comes the Easter. Easter is the most important annual religious feast in the Christian liturgical year. Relatively newer elements such as the Easter Bunny and Easter egg hunts have become part of the holiday's modern celebrations, and those aspects are often celebrated by many Christians and non-Christians alike.

Pls kindly note we will have a 4-day holiday from 25th to 28th March. Do you have order for us about electronic components before this holy vacation?

Kingtronics team wish you have a Happy Easter! 

Recently we are so happy to hear that our business partner Sacoel has put Kingtronics logo on their company calendars. It is very pretty and well-designed.

Sacoel took this action because they consider Kingtronics to be a reliable and excellent supplier.

Hope to gain a better business with Sacoel in 2016, and we will support you sincerely all the time. Thanks for all your hard work & endeavors.

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.

CONTACT RESISTANCE VARIATION: (CRV)
The apparent resistance seen between the wiper and the resistance element when the wiper is energized with a specified current and moved over the adjustment travel in either direction at a constant speed. The output variations are measured over a specified frequency bandwidth, exclusive of the effects due to roll-on or roll-off of the terminations and is expressed in ohms or % of Rt.

EQUIVALENT NOISE RESISTANCE: (ENR)
(Wirewound only) Any spurious variation in the electrical output not present in the input, defined quantitatively in terms of an equivalent parasitic, transient resistance in ohms, appearing between the contact and the resistive element when the shaft is rotated or translated. The Equivalent Noise Resistance is defined independently of the resolution, functional characteristics and the total travel. The magnitude of the Equivalent Noise Resistance is the maximum departure from a specific reference line. The wiper of the potentiometer is required to be excited by a specific current and moved at a specific speed.

RESISTANCE-TEMPERATURE CHARACTERISTIC: (RTC)
The difference between the total resistance values measured at a reference temperature of 25°C and the specified test temperature expressed as a percent of the Total Resistance.
Where:
R1 = Resistance at reference temperature (25°C) in ohms
R2 = Resistance at the test temperature in ohms