(71B) Basic Bridged-T Notch Filter

[Eddie W. Shore]

Basic Bridged-T Notch Filter

The program NOTCH calculates the required capacitor and resistor to null out an undesired frequency.

Inputs: inductance (H), frequency to nullified (Hz), resistance of the required coil (Ω)

Source: Rosenstein, Morton. Computing With the Scientific Calculator Casio: Tokyo, Japan. 1986. ISBN-10: 1124161430

Program NOTCH
244 Bytes, 12/22/2016

Code:

10 DESTROY L,F,I,C,R
20 DISP “INDUCTANCE” @ WAIT 1
22 INPUT “in H: “; L
24 DISP “FREQUENCY” @ WAIT 1
26 INPUT “in Hz: “; F
28 DISP “COIL’S RESISTENCE” @ WAIT 1
30 INPUT “in Ω: “; I
40 C = 1/(2 * PI^2 * F^2 * L)
42 R = (PI * F * L)^2 / I
44 DISP “NOTCH CAPACITOR” @ WAIT 1
46 DISP C; “ F” @ PAUSE
48 DISP “NOTCH RESISTENCE” @ WAIT 1
50 DISP R; “ Ω”

Notes:
Capital Omega Character (Ω): [ g ], [RUN] (CTRL), [ Q ]

Example: L = 0.12 H, F = 1170 Hz, Coil Resistance = 30 Ω
Output:
NOTCH CAPACITOR ≈ 3.08402 * 10^-7 F
NOTCH RESISTENCE ≈ 6485.04070 Ω