Trimmers, Variable Capacitors

Image	Part Number	Description / PDF	Quantity	Rfq
	GMA41200 Sprague Goodman	CAP TRIMMER 330-1100PF 175V TH	0
	GHL23000 Sprague Goodman	CAP TRIMMER 0.8-23PF 1250V TH	0
	GMB20200 Sprague Goodman	CAP TRIMMER 4-20PF 175V TH	0
	GEN42000 Sprague Goodman	CAP TRIMMER 1-42PF 750V TH	0
	GAA16001 Sprague Goodman	CAP TRIMMER 2-16PF 250V PNL MNT	0
	GME50801 Sprague Goodman	CAP TRIM 425-1260PF 500V PNL MNT	0
	GKG40015 Sprague Goodman	CAP TRIMMER 7-40PF 100V TH	0
	GFN52000 Sprague Goodman	CAP TRIMMER 1-52PF 750V TH	0
	GMC20200 Sprague Goodman	CAP TRIMMER 4-20PF 175V TH	0
	GEL42000 Sprague Goodman	CAP TRIMMER 1-42PF 1000V TH	0
	GMA70400 Sprague Goodman	CAP TRIMMER 25-150PF 250V TH	0
	GHW17000 Sprague Goodman	CAP TRIMMER 0.8-17PF 750V	0
	GDT5R526 Sprague Goodman	CAP TRIMMER 1-5.5PF 250V TH	0
	GKU30018 Sprague Goodman	CAP TRIMMER	0
	GME90201 Sprague Goodman	CAP TRIM 10-48PF 2000V PNL MNT	0
	GGL12000R Sprague Goodman	CAP TRIMMER 0.8-12PF 1250V TH	0
	GMB40300 Sprague Goodman	CAP TRIMMER 20-180PF 175V TH	0
	GUN1R250 Sprague Goodman	CAP TRIMMER 0.3-1.2PF 500V TH	0
	GME11401 Sprague Goodman	CAP TRIM 1300-2830PF 250V PNL MT	0
	GMB20600 Sprague Goodman	CAP TRIMMER 25-115PF 175V TH	0

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.