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