A filter modifies signals based on their frequency.
1
vote
0answers
50 views
Tuned Amplifiers
I'm trying to fully understand some tuned amplifier circuits and i guess this should be really simple to you guys.Here are them:
I would like ask you three things things, each one regarded to ...
-3
votes
0answers
60 views
Audio Filtering [closed]
I have some doubts about how to implement a solution for the app that I explain below:
I want to filter specific audio sounds (truck, trumpet...) with an arduino and a microphone (amplifier + ...
3
votes
1answer
81 views
Strange behavior from variable-gain amplifier
Sorry, this might not go anywhere. My first SE question, though, on any site.
I've built at least three distinct audio amplifiers with the TDA7056B, which is a really great amp. It takes a voltage ...
1
vote
1answer
82 views
simple pre-amp for ELF antenna?
I'm looking to build an antenna to research the 5-500 Hz range. I already had decent success with just a simple square loop 1.5 ft per side (air core), about 12 turns. Despite having an estimated ...
1
vote
2answers
99 views
Transfer Function Of Multiple Feedback Filter
Can someone please give me tips on how I could prove that the transfer function of the multiple feedback filter below is
\$
T(s) = \dfrac{ -\dfrac{1}{R_1 R_2 C_1 C_2 } } {s^2 + s\dfrac{1}{C_1} ...
1
vote
2answers
64 views
Is there any program that I can use to find the transfer function of a filter?
I need to find the transfer function of Sallen-Key second order notch filter.
Is there any program that can show the transfer function of s?
3
votes
1answer
65 views
Help with Notch Filter design
I'm working on a homework problem for my Circuits as Systems class, and I'm having trouble with one of the problems. We are currently covering filter synthesis, and have covered cascaded, Butterworth, ...
1
vote
1answer
43 views
Derivation of filter tables
Could someone please point me in the right direction for finding derivations showing how normalised filter table values come about? What should I be searching for to find the derivations?
I've ...
-1
votes
1answer
52 views
Vibrotactile graphic equilizer? [closed]
I'm very new at this, but here goes: I work with adults who are both deaf and blind. I'm trying to basically build a graphic equalizer that has vibration motors instead of LED's. It would be worn on ...
0
votes
0answers
41 views
Band Reject Filter Transfer Function Help (MathCAD)
I designed a broadband filter for one of my classes and in MathCAD I used this function to plot the expected transfer function of the Band Reject Filter. However when I input the values for it, it ...
2
votes
1answer
62 views
Finding values of LRC circuit when frequency is given
I am trying to solve the following question. The original question is:
The given impedances of the series LRC circuit are established at an
angular frequency of 2000 rad/s.
Calculate the ...
-2
votes
1answer
69 views
Passive and active filter design [closed]
I'm very interested in filter design and would like to learn more about them; however, I don't want to waste my time learning about them if there is no point. I already know the basics of filters and ...
0
votes
2answers
71 views
Effective highpass filter with one opamp
I have a phototransistor giving me some noise at about 100Hz and I am transmitting an IR signal at it of 10khz. I would like to completely eliminate the noise since it would be amplified at later ...
2
votes
2answers
141 views
Designing parallel RLC band-stop filter in series with load from f0, gain, Q parameters
I've been trying to design a band-stop filter for my headphones to cut back on excessive highs and to provide a more flat frequency response.
With a software EQ and lots of tries, I managed to arrive ...
0
votes
1answer
108 views
Active low pass filter giving constant output regardless of input
I have a sensor that gives me an output between 1 and 4V, and I wanted to filter out noise present on the output to give me a more stable and accurate reading.
I set up an active 2nd-order ...
2
votes
1answer
104 views
How to show that this filter is a bandpass filter [duplicate]
i got a system with transfer function given by:
$$H(\omega)=1-e^{-j\omega}$$
I already plot it, and that seems to be a periodic function with $$H(0)=0$$ $$H(\pi)=2$$ $$H(\infty)=1$$ is that enough to ...
1
vote
2answers
161 views
transfer function of active filters
I've been looking for some straightforward method or trick to obtain the transfer functions of active filters (like the Sallen-Key filter , the butterworth or Cauer topology etc...) since KCL or KVL ...
1
vote
1answer
70 views
Is it possible to compute delay with an IIR filter between peaks?
I am developing a project which receives accelerometer signals as input, which must then be analysed via peak-detection algorithms (among other techniques).
In order to do so more effectively, I ...
2
votes
3answers
89 views
Is a IIR digital filter with a0=1 effectively a FIR digital filter?
I have been experimenting with several digital filters for my thesis recently, and while learning about the FIR and IIR kind, they seem to have similar output expressions.
While using a Java class I ...
5
votes
5answers
206 views
How to recognize the type of analog filter given its topology?
Having trouble to tell what kind of filter (Low-Pass, High-Pass, Band-Pass, Band-Reject(Notch) are present given a topology in cascade.
In the following picture I see 3 stages, is this ok? (2 active ...
2
votes
1answer
73 views
How is noise reduced using a sigma-delta converter?
Perhaps I'm sleepy but I can't quite get my head around how a sigma delta converter takes the noise that is in a bandwidth of (X) Hz and by over sampling spread, that same amount of noise over 2(X)Hz. ...
2
votes
1answer
117 views
Is a low load resistor a big problem in low pass filter and amplifier circuit
I am going to use AVR's PWM output signal to pass through a low pass filter (maybe plus an amplifier). I found the speaker has a quite low resistance (8 ohms). I tried to simulate my schematic on ...
2
votes
0answers
126 views
Why is the loaded Q of a critically coupled two-resonator circuit approximately equal to 0.707 times the loaded Q of one of its resonators?
From RF Circuit Design by Christopher Bowick (page 32 bottom of the page left column):
The loaded Q of a critically coupled two-resonator circuit is
approximately equal to 0.707 times the loaded ...
-5
votes
2answers
104 views
Designing FIR filters [closed]
How can we realize a second order digital FIR filter without using a microcontroller. What assumptions would be taken?
4
votes
1answer
173 views
Differentiator Circuit
So I have a circuit like this:
With the output equation as: \$ V_{out} = -(\frac{R_2}{R_1})\frac{s}{s+\frac{1}{R_1C}} V_{in} \$
So the question is to derive the time-domain equation in terms of the ...
5
votes
1answer
286 views
When to use buffer/ low-pass filter on ADC input?
Sorry if this is a bit of a sophomoric question, but when should you buffer an ADC input, specifically from a potentiometer. I've seen circuits add a low-pass to the wiper/ ADC input.. is this only ...
-1
votes
1answer
235 views
What is the use of an LCL Filter?
Can someone explain what is the use of an LCL filter and where is it used? I searched for it online but couldn't find any materials.
2
votes
1answer
190 views
Sallen-Key filter problem
I am an Electrical Engineering student and I'm making a relay test for dad because I want to design stuff. Basically, there is an oscillator switching the relay constantly, and there is a \$ ...
0
votes
1answer
162 views
Q value of a passive single stage RC low pass filter
I'm a student trying to understand filters. I would like to know what the Q value of a series RC low pass filter is. As far as I'm aware, one can't design for it, but I'd still like to know what it ...
8
votes
5answers
1k views
Analyzing Accelerometer data characteristics and designing a filter
I have about 32 seconds worth of accelerometer data of a basic driving scenario 25MPH normal roads along with hitting about 7 potholes and a rough patch of road. The accelerometer is mounted on the ...
3
votes
1answer
325 views
PCB stub antenna impedance matching
I'm about to design a 433MHz transceiver and found a nice reference design using the TRC105 and the RF3608D SAW Filter.
Before designing the circuit I wanted to understand the impedance matching in ...
8
votes
3answers
423 views
Audio Amplifier Op amp
I'm trying to design a circuit in which a microcontroller produces a signal and then using an amplifier drives an 8ohm speaker.
I've so far used LM386, but it cannot go above 1W, which turned out to ...
3
votes
1answer
134 views
Bandpass Filter Design 6Mhz/6.5Mhz Center Approx +/- 250khz passband for ATV system
I'm looking to build two bandpass filters centered at 6Mhz and 6.5Mhz, with an approximate passband of 250kHz. I want to replace these two filters:
http://www.yoketant.com.tw/yoketant/ceramic-7.htm
...
1
vote
1answer
122 views
Where to place a RC filter regarding decoupling capacitor?
I would like to add a low-pass RC filter (500Hz) to the power rail of a TLV2782 op-amp. Datasheet of TLV2782 recommends two decoupling capacitors: 0.1uF and 4.7uF and they are currently placed on the ...
3
votes
1answer
251 views
Low-pass filter on microcontroller output
I'm producing a signal which contains 7 frequencies using a microcontroller with a DAC. the frequencies are 16.5kHz 16.7kHz 16.9kHz 17.2kHz 17.4kHz 17.6kHz 17.8kHz. and sampling frequency (at the ...
1
vote
1answer
69 views
Vrip equation doesn't seem to work
Okay I got a question on how to design a full wave rectifier circuit.Okay I just read a text-book of malvino's principles on electronic and devices.
Let me tell you I have an input voltage of 64 ...
3
votes
1answer
89 views
What EMC considerations need to be made with RF bias-t with 3-4A of current consumption?
After getting a great answer on how to couple a signal on to a DC line, I wonder what EMC considerations that has to be done with using a bias-T circuit used for communications with a ~130kHz QPSK ...
2
votes
2answers
123 views
Analog Audio Tape Equalization: Why a Time Constant instead of a Corner Frequency?
For recording or playing back audio signals with analog tape, frequencies on the low and high ends of the audio spectrum are run through filters (equalized). The filters are standardized. The goal is ...
3
votes
2answers
502 views
What is the purpose of a capacitor to ground?
I have here a filtering circuit from a microwave. What is the point of the capacitors to ground. Another answer in a previous question of mine said they were used for filtering however I don't ...
2
votes
1answer
279 views
How do I calculate parameters of LC filter from component values?
I have found this schematics and want to know corner frequency and characteristic impedance of this filter. How do I calculate it?
0
votes
3answers
222 views
Eliminate hiss and noise
ATTiny is generating PWM based tones with 32kHz sampling rate. Then I've created R-2R DAC and then trying to amplify it for the speaker.
I need to make low pass RC filter, to cut PWM hiss during ...
1
vote
1answer
215 views
Simulation of Band-Pass Filter (RLC) in ngspice
*I think I've found the answer myself. Check out the question comments.*
Sorry for my bad English, I'm still learning it.
This week I started using ngspice. I've built some simple circuits to get ...
1
vote
3answers
197 views
How to reduce the clock jitter for an ADC?
I am building a SDR (Software defined radio) and I am trying to clock my 16 bit 130 MS/s ADC. At this speed, the jitter of the clock is very important and a bad jitter can reduce the SNR of my ADC a ...
2
votes
1answer
126 views
What “rule of thumb” to use for mapping -3dB frequency to ideal response for 2nd order Sallen-Key?
For a first order passive filter (RC circuit), we often reach for a the familiar 10X rule. If the -3dB corner frequency is f, then "ideal" frequency response starts at 10f.
What similar factor can be ...
1
vote
3answers
299 views
Transfer Function and Bode Plot from Poles and Zeroes
I've got the following bode plot from a black box:
I've calculated the zero to be 1055 and pole to be 67. Thus I'm using the transfer function \$H(s) = (s-1055)/(s-67)\$ but this gives a clearly ...
4
votes
2answers
143 views
Question about the derivation of filtering roll off
I don't understand the following step in my notes:
It is about filter roll-off.
$$H(\omega)={1\over 1+j(\omega/\omega_c)}$$
$$\Rightarrow|H(\omega)|= {1\over \sqrt{1+(\omega/\omega_c)^2}}$$
where ...
0
votes
1answer
74 views
Highly accurate CMOS Squave wave clock signal to drive MF5CN Audio filter
The task is to generate a CMOS (+-5[V]) square wave signal with 50% duty cycle in order to drive a second order active filter IC (MF5CN) with variable or fixed frequencies of 150[Khz], 300[kHz], ...
2
votes
1answer
254 views
Flash an LED to music
Im trying to flash an LED to music.
I have tried to follow this article and calculate values but cannot get it to go.
Basically what i think i need is:
audio in
through a low pass filter (isolate ...
4
votes
2answers
257 views
Tunable Lowpass Filter
I would like to design and build a tunable lowpass filter. I would like to adjust the cutoff frequency from 1 MHz to 500 MHz. Requirement on the resolution would be something like 10-50 MHz, ...
2
votes
2answers
119 views
capacitive filter design
I have a question about output capacitor filters.
So I know that a simple capacitor filter would have a single pole response, and this is just a first order filter. Let's say that the value of the ...
