Application of mylar capacitor
Mylar capacitor is an essential component in electronic products. They act as filters, oscillations, power supply decoupling, bypassing and coupling of ripple signals in the circuit.
Composition of mylar capacitor
The simplest structure of a mylar capacitor can be composed of a layer of insulating medium sandwiched between two metal plates. A voltage is applied between the two metal plates (the plates) to store the charge. The magnitude of the stored charge is proportional to the plate-to-plate voltage and the plate area (capacity), and inversely proportional to the distance between the plates. Q=CV is C=Q/V=εS/4πd (“See the theoretical calculation and correction of film capacitors”) Q—The charge stored on the plate; C—Capacitor (PF); V—Varisity between plates (V ε – dielectric constant of the medium (3.0 for polyester film, 2.1 for polypropylene film); S – area of metal plate (mm2); d – distance between plates (mm).
Mylar capacitor parameter marking method
♦ Straight standard method
The main parameters of the capacitor (nominal capacity, rated voltage, and allowable deviation) are directly marked on the capacitor, such as 0.0047μf / 275V, 0.0047μf is the capacity, equivalent to 4700Pf, 275V should be withstand voltage (not preferred series) .
♦ Text notation
The main parameters of the capacitor are labeled by a number or a mixture of letters and numbers.
1. Digital notation Generally, the capacity of a capacitor is represented by a 3-digit number. The first two digits are the rms digits, and the third digit is the multiplier (ie, how many zeros are there after the rms value). For example, 104 indicates that the effective value is 10, followed by four zeros, that is, 100000 Pf=0.1 μf.
2. Mixed combination of letters and numbers Use 2-4 digits to represent the effective value, and use P, n, M, μ, G, m and other letters to indicate the magnitude after the significant digit. Imported capacitors do not use a decimal point when marking values, but write the integer part before the letter and the decimal part after the letter. For example, 4P7 represents 4.7Pf, and 3m3 represents 3300μf (3.3mf) or the like.