Questions tagged [analog]

Analog circuits have a range of voltages, rather than just two as in digital logic.

331 questions with no upvoted or accepted answers
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188 views

Help with deciding my layout for EMC tests and SI. Different alternatives

I am thinking of what way would be the best to layout my system in order for it to have the best SI and pass EMC tests. My system consists of two PCBs joint by a flat flex cable (up to 7cm) and these ...
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144 views

imx6q sabre board microphone

I have been trying to record audio using the circuit below. It is different from the normal microphone circuit in that the MIC_IN and MICBIAS are separate paths. I tried to connect an electret ...
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52 views

I have a question about the datasheet for AD8330 VGA (variable gain amplifier)

I don't have much experience reading datasheets. I was reading the datasheet for AD8330 VGA. I did not understand what the difference is between VDBS and VMAG. Can someone elaborate on that? It's ...
3
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1answer
84 views

How do determine MOSFET parameters in LTSPICE

I am designing a phase locked loop on LTspice (which I'm new to), but have come across a snag in the procedure: Is there a way to determine the output resistance of a mosfet (as the I'm not able to ...
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0answers
132 views

How to design analogue compensation for SMPS from Bode Plots?

In a complicated switched mode power supply where the transfer function is unknown, is there a way to design an analogue controller and compensation from the bode plot alone? I am having difficulty ...
3
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2answers
124 views

Getting a specific voltage output depending on the difference of two voltages

Can someone please help me come up with a circuit with the following specification? I need to find out the difference of two voltages (can be done using an op-amp). Then, if the difference is negative,...
3
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2answers
70 views

MOSFET pinchoff reduce current

I understand that in an n channel MOSFET as Vgs increases, electrons are attracted towards the gate forming an n channel. These electrons are responsible for the conduction of the MOSFET. As Vds ...
3
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1answer
61 views

Phase shift near saturation mitigation in input stage amplifier — How does this work, why does this work?

I'm trying to understand how this circuit works on the input stage to the 4192A Impedance Analyzer. Apologies for the quality... this is the best scan I could find. The design is furnished with the ...
3
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2answers
697 views

Designing 4th order Butterworth Multiple feedback bandpass filter

I'm trying to design a 4th order Butterworth bandpass filter using Multiple feedback topology. The design requirements I am trying to achieve for this filter are; Q factor = 10, Av = 11, fc = 100kHz ,...
3
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3answers
245 views

Separate grounding for analog and digital portions of circuitry

A datasheet suggests separate grounding for analog and digital portions of circuitry (http://www.ti.com/lit/ds/symlink/am26c32.pdf#page=12). Is this to say that the IC's outputs should have a ...
3
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1answer
199 views

Switching relay on and off affects analog sensor output voltage

I am working on an AVR project that involves measuring tempereture with an analog sensor (TMP36) and switching a heater on and off through relay to keep the temperature at desired level. However, I'...
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0answers
51 views

Does UJT work as amplifier?

I had got a question in job interview " Draw a circuit of common emitter amplifier using Non Bipolar Transistor." As the question said Non Bipolar, so I assumed that it might be related to UJT. But ...
2
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0answers
54 views

Audio amp IC: how does this output stage work?

I'm looking at an audio amplifier integrated circuit and the output stage seems a bit unusual. Has anyone seen this style of output stage, and does it have a name? And can anyone fill in the details ...
2
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105 views

ESP12e: analog reading not working with voltage divider

I'm trying to read from an analog sensor (a capacitive soil moisture sensor). I'm using a ESP12E, not a development board, so the ADC pin can only take 1V max. Since my sensor can output up to 3V, I ...
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0answers
63 views

Op-Amps in custom current limiter acting strangely

I'm building a small current limiter (~20 mA). It's important that there is little drop over the current limiter and that the load receives almost the full supply voltage when it's pulling less than ...
2
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1answer
88 views

Cascade of 555 timer with Control Voltage not triggering

Hi I'm currently working on a cascade 555 circuit, both operating in the monostable mode. I also want to be able to control the pulse width with a voltage so am using applying 0-5v to the ctrl pin (...
2
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1answer
113 views

When to use P-Type current source(using pMOS) and when to use N-type current Source(nMOS)?

I am referring to Prof. Behzad Razavi Lecture https://www.youtube.com/watch?v=GAvZLyii3aw&list=PLiDoPUX9nLkIw9EnIv_3K19wlcyJ6msYd&index=2 (Minutes 19-26) Prof. says to use nMOS when we draw ...
2
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1answer
170 views

How to prove that a circuit has negative feedback?

Queries regarding this circuit: I am able to say that this circuit has negative feedback but my procedure is disorganized. I want a step wise procedure to identify the polarity of feedback. In this ...
2
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0answers
235 views

PWM to synth control voltage improvements

Just built this little circuit to control my Moog Werkstatt. The plan is to make a MIDI-to-CV converter and add more CV outputs and of course a GATE output later. But before going further, I thought I'...
2
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0answers
87 views

High SNR FM demodulation

So I need to demodulate the FM signal from a sensor with highest SNR possible, at least 70-75 dB. IF is 10.7 MHz, max. deviation is 200 kHz but I can change those values if needed. Baseband signal ...
2
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0answers
135 views

How does the biasing work in a JFET based triangle to sinewave converter?

To those who haven't see this cool little circuit it employs the non-linearity and symmetry of the JEFET to clip a triangular signal to make it more sinusoidal Can someone please explain to me how ...
2
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1answer
523 views

Arduino - Using NPN transistor as a switch to pull-up/down analog pin

Let me start by saying that I am not an EE, and my knowledge in Electronics is basic, so please bear with me and be patient if, initially I am bending a few rules. In Epee fencing, a touch is awarded ...
2
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1answer
244 views

Calculating drain current with series N-channel MOSFETs

When two N-channel MOSFETS are connected in series, with common gate connections, then how can I analyze this circuit to determine Id through these MOSFETS, as a function of Vgs and Vds? simulate ...
2
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0answers
74 views

Noise immunity of single ended analog voltage signal

I want to use a sensor with analog output in my design. The output of the sensor is a low frequency traingular wave (less than 300 Hz) and voltage vetween 0 - 5V. I need to carry the sensor signal to ...
2
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1answer
123 views

Simple analog circuit to simulate acceleration and braking behaviour in scale models

Background Scale-model road systems such as Faller https://www.faller.de utilise vehicles that follow a ferromagnetic wire embedded in the road surface. The vehicles operate at full speed and continue ...
2
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1answer
556 views

Dolby HX PRO implementation on existing tape recording deck

I'm experimenting the implementation of Dolby HX PRO's IC into an old stereo Fostex tape deck to improve high frequency and headroom capabilities. HX PRO works as a dynamic processor with the BIAS ...
2
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1answer
361 views

Programmable Electronic Load Design

I am trying to design a programmable electronic load for testing the PWM outputs of PLC controllers. The outputs operate between 5-36 V and 10-2000 Hz frequency. The output is supposed to tested for ...
2
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0answers
133 views

Trying to figure out what kind of input signal this loudspeaker amp circuit needs

I'm still trying to figure out how this door intercom module works. It's a 18y old siedle TLM 611-0 module, I figured out the mic part, there the audio signal is modulated onto the current the mic amp ...
2
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0answers
185 views

Asking about old russian amplifier internal circuit

I worked with an old russian machine in my lab, which contains an input from a photodiode with amplification circuit. The amplification is composed into 2 stages , the first with a JFET transistor ...
2
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0answers
308 views

Op-amp circuit saturates to negative rail and only passes positive side of input

I've been working on a spring reverb driver circuit, based mostly on figure 5 from this site: https://sound-au.com/articles/reverb.htm. While there's lots of information on the how of the circuit, ...
2
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2answers
4k views

Thevenin Equivalent of BJT Transistor

I wonder if I can replace a BJT transistor operating in active mode, with its Thevenin Equivalent, like this: My guess is that I can, because the large signal model of the BJT operating in active ...
2
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2answers
218 views

Are there any filter design tools that can design an LC Low pass filter with unequal in/output impedance?

All the tools I have used so far design for matched impedance, I need something,preferabely free which gives me this option. the requirement is for a higher ( >=4) order filter, lossless, for a 8 ohm (...
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0answers
4k views

MOSFET Parameters LTSpice

This is the LTSpice model of the Fairchild 2N7002 NMOS transistor. ...
2
votes
1answer
175 views

Noise in FET reverse-polarity protection for ADC

I have quite precise ADC circuit. I want to protect input supply voltage (not ADC input) from reverse-polarity using FET transistor as shown on the picture below. I wonder: is there any noise / worse ...
2
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1answer
439 views

ac voltage regulator

I'm trying to built a circuit that amplifies music from a phone to a headset, based om ambient noise level. So if you're surrounded by noise, your music volume will turn up and in silent surroundings ...
2
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0answers
2k views

How to find the resonant frequency of a human body?

I've read that the human body has resonant frequencies somewhere around 50MHz. I also think it would be interesting to look for values in other ranges like 10-100 kHz. I'm wondering how to build a ...
2
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0answers
573 views

Convert [-24V,24V] range analog signal to [0V,3.3V] range for ADC

I need to realize a circuit that converts an analog signal from [-24V,24V] to [0V,3.3V] before sending that signal to an ADC "MCP3208". I found the circuit in the picture below and it works perfectly ...
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0answers
1k views

100kHz active filter design

I am designing a basic 100kHz active bandpass filter using opamps (LF353). I am only interested in receiving the 100kHz frequency (might drift a few kHz) from my input signal. I have used a basic ...
2
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0answers
106 views

Coupling vs Decoupling filter / Filter in-the-signal-path vs filter on-the-signal-path

I'm looking at designing an active analog filter module to be used/reused in my designs. Correct me if I'm wrong, but you can design a filter that is in the signal path that has the same frequency ...
2
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1answer
574 views

Shut down circuit sections

I am currently devising ways to shut off different circuit sections in an embedded circuit. Here is a breakdown of what I am doing and my initial idea. Currently I have a micro controller which is ...
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2answers
96 views

LASER diode driver circuit

I have some problems on understanding how this circuit works. Its aim is that of: bias correctly the LASER diode at left send a signal (DATA) to the LASER diode stabilize the working point of the ...
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2answers
43 views

Help needed to determine inductor material/turns needed

I am trying to formulate a circuit to sense current in a standard US 120V AC power line. I'm planning on using an inductor as a current transformer to sense current flow and allow a microcontroller ...
1
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1answer
31 views

Evaluation of input and output impedance of a RF amplifier

I have a doubt about the meaning of input and output impedance of RF amplifiers. I'll take as example the amplifier CMA-252LN by Mini Circuits . In its datasheet it is not clearly written their input ...
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0answers
64 views

How do you draw a DC equivalent circuit of a circuit which has an AC voltage source and a diode?

I am studying analog electronics now and I have encountered this problem for my assignment which I have some serious problems solving, wondering if anyone can provide some help. i have searched around ...
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2answers
75 views

4 - 20 ma current loop, Short circuit isolator

I am trying to design a short circuit isolator, for 4 - 20 ma current loop based intruder alarm system.The below system,identify short circuit in sensing line and sensor activation(closing 1 k in line)...
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0answers
35 views

How to calculate the current through load resistance in the given diagram?

I am here with yet another problem, where I have to find load current, ripple voltage, approx turns ratio? Also, any idea about how can we reduce ripple voltage further? Attempt: This is a step-down ...
1
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1answer
65 views

12V PWM to Analog DC converter for car cooling fan

I’m installing two 12V 80W cooling fans in an old BMW which originally uses a PWM electric fan. This original fan has a three pin connector (constant 12v, ground and PWM signal from the ECU). I ...
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0answers
63 views

Will a lower resistance potentiometer improve a panel meter scale reading?

I have an analogue tacho/RPM panel meter on an auto distributor tester, c1950s. This is not the original meter. It has two scales 0 - 6000 rpm and 0 - 1000 rpm, with a toggle switch between the two. ...
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0answers
99 views

Can I use an optocoupler to switch an analog signal?

I have this setup to select 1 of 4 signals, pass it through a sensor, then output it to its own output line. It must also maintain all the signals at the output at all times, using optocouplers as ...
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0answers
25 views

How can I add an offset voltage at the input of an instrumentation amp?

I want to measure the voltage of an H-Bridge Sensor. However, due to the manufacturing process, the bridge has an offset several times larger than the useful signal (it can easily measured by ...

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