Capacitor Calculators
A comprehensive suite of calculators for capacitor calculations, helping you with everything from basic value conversion to complex circuit analysis and timing calculations.
Value Converter
Convert between capacitance values and units (pF, nF, µF, F)
SMD Code Calculator
Convert SMD codes to capacitance values for surface mount capacitors
Series Calculator
Calculate total capacitance and voltage distribution for series connections
Parallel Calculator
Calculate total capacitance for parallel connections
Charging Calculator
Calculate charging time, current and voltage for capacitor circuits
Discharge Calculator
Calculate safe discharge time and resistor values
Impedance Calculator
Calculate capacitive reactance and impedance at different frequencies
Time Constant
Calculate RC time constant and related parameters
Quick Reference
Capacitive Reactance
Xc = 1/(2πfC)
f = frequency in Hz
C = capacitance in Farads
Series Connection
1/Ctotal = 1/C1 + 1/C2 + 1/C3 + ...
Parallel Connection
Ctotal = C1 + C2 + C3 + ...
Time Constant
τ = RC
Charge: V = V0(1 - e^(-t/RC))
Discharge: V = V0(e^(-t/RC))
Frequently Asked Questions
Basic Concepts
What is capacitance?
Capacitance is the ability to store electric charge. Key points:
- Measured in Farads (F)
- Common units: µF, nF, pF
- Depends on physical construction
- Affected by dielectric material
How to read capacitor values?
Capacitors use various marking schemes:
- Direct value marking (e.g., 100µF)
- 3-digit codes (e.g., 104 = 100,000pF)
- SMD codes for surface mount
- Letter codes for tolerance
Circuit Applications
Timing Circuits
Design considerations for RC timing:
- Calculate time constant (τ = RC)
- Consider voltage thresholds
- Account for component tolerances
- Temperature effects on timing
Filtering Applications
Key points for filter design:
- Calculate cutoff frequency
- Consider impedance matching
- Account for ESR effects
- Frequency response requirements
Design Guidelines
Voltage Rating Selection
Important considerations:
- Use 2x safety margin
- Consider voltage transients
- Temperature derating
- Ripple voltage effects
ESR and Ripple Current
Critical parameters:
- Check ESR specifications
- Calculate power dissipation
- Verify ripple current rating
- Consider frequency effects
Safety Considerations
Discharge Safety
Essential safety practices:
- Always discharge before handling
- Use appropriate discharge resistor
- Verify voltage with meter
- Consider stored energy (E = ½CV²)
Failure Modes
Common issues to prevent:
- Reverse voltage damage
- Excessive ripple current
- Overtemperature operation
- Voltage stress failures
Technical Details
Capacitor Types
Electrolytic Capacitors
High capacitance, polarized devices:
- Aluminum electrolytic: General purpose, cost-effective
- Tantalum: High reliability, stable temperature characteristics
- Polymer: Low ESR, high ripple current capability
- Typical values: 0.1µF to 100,000µF
Ceramic Capacitors
Common in high-frequency applications:
- Class 1 (C0G/NP0): Stable, low loss, precise values
- Class 2 (X7R, X5R): Higher capacitance, temperature sensitive
- Class 3 (Z5U, Y5V): Highest capacitance, most variable
- Typical values: 1pF to 100µF
Application Circuits
Power Supply Applications
Key design considerations:
- Input filtering: Reduce EMI and transients
- Bulk storage: Maintain DC bus voltage
- Output filtering: Reduce ripple voltage
- Bypass/decoupling: Local charge storage
Signal Processing
Common applications:
- AC coupling: Block DC, pass AC signals
- Filter networks: Active and passive designs
- Sample and hold circuits
- Peak detectors and integrators
Performance Parameters
Temperature Characteristics
Critical specifications:
- Operating temperature range
- Temperature coefficient of capacitance
- ESR variation with temperature
- Lifetime vs. temperature ratings
Frequency Response
Important characteristics:
- Self-resonant frequency (SRF)
- Impedance vs. frequency
- Q factor and dissipation factor
- Bandwidth limitations
Selection Guide
Application Requirements
Key selection criteria:
- Operating voltage and current
- Capacitance stability needs
- Frequency range requirements
- Environmental conditions
Reliability Considerations
Factors affecting lifetime:
- Operating temperature margin
- Voltage derating guidelines
- Ripple current limitations
- Environmental stresses
Design Resources
Design Tips
Essential guidelines for successful capacitor implementation:
- Always consider the full operating temperature range
- Account for component tolerances in critical applications
- Use appropriate safety margins for voltage ratings
- Consider PCB layout effects on performance
- Implement proper grounding techniques
- Plan for maintenance and replacement access
Common Mistakes
Issues to avoid in capacitor applications:
- Insufficient voltage derating
- Ignoring temperature effects on lifetime
- Poor ESR matching in parallel configurations
- Inadequate ripple current rating
- Improper lead length in high-frequency applications
- Neglecting mechanical stress considerations