Trimmers, Variable Capacitors

Part Number	Description / PDF	Quantity
9812SL Knowles Johanson Manufacturing	CAP TRIMMER 4-18PF 250V SMD	1756
GAA3R501 Sprague Goodman	CAP TRIM 0.35-3.5PF 250V PNL MNT	35
2320-3R1 Knowles Johanson Manufacturing	CAP TRIMMER 5-18PF 250V SMD	285
GAA3R503 Sprague Goodman	CAP TRIM 0.35-3.5PF 250V CHAS MT	81
JZ300HV Voltronics (Knowles)	CAP TRIMMER 5.5-30PF 350V SMD	6022
GKG3R015	CAP TRIMMER 1-3PF 100V TH	4218
GKG10015	CAP TRIMMER 3-10PF 100V TH	1170
SGNMA3T20001 Sprague Goodman	CAP TRIMMER 2-20PF 1000V PNL MNT	0
PC52J5R5 Sprague Goodman	CAP TRIMMER 0.8-5.5PF 750V TH	27
SGC3S060NM	CAP TRIMMER 2-6PF 100V SMD	3095
GZD10100 Sprague Goodman	CAP TRIMMER 9-100PF 100V TH	4599
GAA3R513 Sprague Goodman	CAP TRIMMER 0.35-3.5PF 250V TH	480
GXD60000 Sprague Goodman	CAP TRIMMER 6-60PF 100V TH	296
GMB30200 Sprague Goodman	CAP TRIMMER 7-40PF 175V TH	37
GAA10003 Sprague Goodman	CAP TRIMMER 1-10PF 250V CHAS MNT	98
GUR1R200 Sprague Goodman	CAP TRIMMER 0.3-1.2PF 500V TH	31
GEN28000 Sprague Goodman	CAP TRIMMER 1-28PF 750V TH	45
118-31027 EXXELIA	CAP TRIMMER 0.3-1.2PF 500V TH	0
GYB27000 Sprague Goodman	CAP TRIMMER 2.3-27PF 100V TH	4598
5453 Knowles Johanson Manufacturing	CAP TRIMMER 1-16PF 250V TH	259

Trimmers, Variable Capacitors

1. Overview

Trimmer capacitors and variable capacitors are specialized capacitive components with adjustable capacitance values. Trimmers are semi-fixed capacitors designed for infrequent adjustments during device calibration, while variable capacitors allow continuous manual or mechanical tuning. These components are critical in analog circuits, RF systems, and precision electronics, enabling fine-tuning of frequency response, impedance matching, and signal optimization. Their adaptability makes them indispensable in communication systems, industrial control, and measurement instruments.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
Ceramic Trimmer Capacitors	Compact size, high stability, ceramic dielectric material	Radio transmitters, oscillator circuits
Film Trimmer Capacitors	Low leakage current, polymer film dielectric	Medical equipment calibration
Air Variable Capacitors	Adjustable plate spacing with air dielectric	AM/FM radio tuning circuits
Film Variable Capacitors	Rotary adjustment mechanism, plastic film dielectric	Signal generators, test equipment
Electrolytic Variable Capacitors	Polarized design with liquid/gel electrolyte	Power supply filtering systems

3. Structure and Composition

Typical trimmer capacitors use a ceramic or polymer dielectric sandwiched between metal plates, with a screwdriver-adjustable electrode for capacitance variation. Variable capacitors employ either rotating plate systems (air dielectric) or compressible film stacks. Key components include:

Dielectric material (ceramic, polypropylene, polystyrene)
Movable electrode assembly (rotary/sliding contact)
Calibration scale for precise adjustment
Protective housing (epoxy, plastic, or metal casing)

4. Key Technical Parameters

Parameter	Description	Importance
Capacitance Range	Adjustable capacitance limits (e.g., 1-10 pF)	Determines circuit tuning flexibility
Rated Voltage	Maximum operating voltage (50-200V typical)	Affects reliability and dielectric breakdown resistance
Temperature Coefficient	Capacitance variation per C ( 5 to 100 ppm/ C)	Impacts frequency stability
Adjustment Resolution	Minimum achievable capacitance change	Critical for precision calibration
Mechanical Life	Number of adjustment cycles before failure	Dictates component longevity in dynamic applications

5. Application Fields

Telecommunications: RF filters, antenna matching networks
Consumer Electronics: Radio frequency tuning circuits, audio equalizers
Industrial Control: Sensor calibration, power factor correction
Medical Equipment: Diagnostic imaging device signal conditioning
Automotive: Ignition system tuning, radar calibration

6. Leading Manufacturers and Products

Manufacturer	Product Series	Key Features
KEMET	TR3 Series	Ceramic trimmers with 0.5-12 pF range
AVX	VT Series	Vacuum variable capacitors to 1000 pF
Murata	7WT Series	Sub-miniature trimmers for SMT applications
EPCOS	B4350 Series	High-voltage variable capacitors (2000V rating)

7. Selection Guidelines

Determine required capacitance range and adjustment precision
Evaluate environmental conditions (temperature, vibration, humidity)
Select appropriate dielectric material for stability requirements
Consider packaging type (through-hole vs. surface-mount)
Assess mechanical actuation needs (manual vs. motorized tuning)
Verify voltage rating exceeds circuit requirements

Industry Trends and Future Outlook

The market is shifting toward miniaturization (sub-1mm components), enhanced digital control integration, and improved temperature stability ( 5 ppm/ C specifications becoming standard). Emerging applications in 5G infrastructure and IoT devices are driving demand for ultra-low-loss trimmers. Material innovations like nanoceramic dielectrics and MEMS-based variable capacitors are expected to dominate next-generation designs. Environmental regulations are also pushing manufacturers toward lead-free and RoHS-compliant packaging solutions.