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It looks like a first-order passive high-pass shelving filter. Its role is to attenuate low-frequency content of the audio signal without cutting it off. Mainly used to reduce (de-emphasize) excessive bass as a form of coarse equalization via bass-trebble (tone) controls. Some features: Attenuation of low-frequency content is: \$\alpha = 20 \log \big(1+\...


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Here is a PI filter: simulate this circuit – Schematic created using CircuitLab When the frequency is very low, the capacitors are almost open circuit and the inductor is almost a short circuit. As the frequency increases, the capacitors become a lower reactance (thus sinking some of the input signal to ground) and the inductor increases its ...


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tl; dr: The designers didn’t calculate anything really. They likely just followed another design. The LF1/LF2 filter elements are ferrite beads. They suppress common-mode noise coming from the board. This helps the board pass EMC / EMI testing. Ferrite beads are rated in impedance at a given frequency, rather than inductance. In this case, they chose a 220 ...


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Simulate it with a swept sine. Assuming the source is low impedance and the following circuitry is high impedance, it's a 1:3 voltage divider at DC, and passes high frequencies unattenuated. There's a zero at \$\frac{1}{2 \pi \mathrm{(3.3nF)(40k\Omega)}} = \mathrm{1200Hz}\$, and thus a pole at \$\mathrm{3600Hz}\$. So, it's an equalizer (or emphasis) ...


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MIL-STD-3009 and MIL-L-85762 detail the spectrum requirements for NVIS compatible lighting, and include the sensitivity spectra for the for different classes of tubes. The aim is to minimize the output of light that is in the sensitive area of the NVGs. For incandescent lighting this was an issue since most of the output is in infrared, but LEDs generally ...


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Based on comments, you want 20 dB of attenuation. A one pole low-pass filter rolls off at 20 dB per decade above its cut-off frequency. So you'd need to put your cut off one decade below the undesired signal frequency to achieve 20 dB attenuation with a one pole filter. That would be 12 Hz. A two pole filter rolls of at 40 dB per decade. So you'd need to ...


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You will likely want to explore Green filter plastic film to attenuate the broad spectrum that although is only 1% , if your indicator is 1000 mcd the LEDs may still be brighter than your night target and affect the AGC from stray light. https://images.app.goo.gl/S7bDxK96LuqbNx1x7 Normally we examine LEDs with a linear scale which does not show the low ...


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It is a high pass filter and I believe it is part of tone control. You can adjust the high frequency response of the amplifier. It might help to see more of the circuit.


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Ignoring for a moment that that publication seems to be of very low quality (it reads almost like a student assignment, not like a paper/letter from a scientific publication, and at no point really provides any novelty). The difference is simple: A stepped impedance is a section where the characteristic impedance changes. This impedance step causes ...


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A PLL uses integration to eliminate steady state phase error in a stable input. Whereas with a ramp f input, there is a gain-dependant fixed phase-error ( as well as other variables) Not having done FMCW RADAR before, may I refer to an excellent article. It defines all the variables that affect BW , settling time and fixed phase error which is an ...


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One thing that happens as the core begins to saturate is that the inductance value drops, precipitously at saturation. This will change the filters AC characteristics. In a filter application, obviously the AC signals you are trying to block becomes less blocked. Many specifications for inductors intended for filter applications will provide inductance vs DC ...


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