Capacitor types

Types of Capacitors

(in descending order of stability)

• NP0 (negative positive zero, aka 'C0G', aka 'NPO')

- extremely stable in rf oscillators

- temperature stable

- crystal oscillators

- variable frequency oscillators (VFO)

- beat frequency oscillators (BFO)

- rf coupling circuits

- temperature use -55C to 125C

- capacitance change +/- 0 to 30ppm/C

• (silver) mica

- stable over wide temperature range

- rarely fail

- often used for oscillators

- same use as NP0 (RF circuits)

- capacitance change +/- 0 to 50ppm/C

• polystyrene (film)

- good for oscillators

- stable but keep in cool temperatures

- capacitance changes permanently when heated too much

- used in solid state equipment (around tubes is too hot)

• ceramic

- rarely fail

- rf bypass capacitors

- never use for oscillators or tuned circuits

- slightly microphonic

- X5R (-55C to 85C)

- X7R (-55C to 125C)

- Y5V (-30C to 85C)

- Z5V (10C to 85C)

• PP/polypropylene (film) (orange/brown/green drop)

- rf coupling

- good for audio amps

- not for oscillators

- not very stable

• PET/polyester (film) (MKT, Mylar)

- heat and humidity resistance

• tantalum

- not for audio

- non-linear

- good for rf bypass

- good for timing (e.g. 555)

- available in capacitances well above 1uF

- polar

- temperature stable

• Electrolytic (aluminium film)

- poor stability

- available in capacitances well above 1uF

- good for timing (e.g. 555)

- polar

• paper in oil

- stability ok

- replace (paper goes acidic over time)

- replace with polypropylene

• foil capacitor (old style)

- stability ok

- replace with polypropylene