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# Questions tagged [analog]

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

522 questions with no upvoted or accepted answers
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1k views

### Overvoltage protection circuitry choice

I need to design a input overvoltage protection for a 45 W DC-DC converter rated for a 9-24 V wall wart input (so, 45W/9V = 5 A input current at max). So far I've seen two approaches (schematics below)...
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### 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 ...
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### How to understand a complex diode-resistor function generator circuit?

I'm reverse-engineering a CRT anti-pincushion circuit and it uses a complex diode-resistor circuit to approximate the function X-k×X×Y², where X and Y are the deflection voltages. My question is if ...
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### Detection of CT secondary subsidence current

In utility power system protection we have a protection function called "breaker failure" protection. This protection is used to take appropriate action if/when a circuit breaker fails to ...
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### 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 ...
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856 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 ...
150 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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636 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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### Sinking an input when pulses are above a certain frequency

I'd like to use a liquid flow meter of type YF-S401 at 12VDC. It produces 1.7-35k pulses per minute (rise time: 0.04us, fall time: 0.18us). I want to trigger a sinking input of a controller board if ...
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### 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 ...
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### 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 ...
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### 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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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 ...
109 views

### 50 Ohm-Terminated Antenna Oscilloscope Readings

As a follow up to my previous question about measuring antenna performance via amplitude at 88 MHz to 108 MHz on a DSOX1102G oscilloscope, can I trust these new readings? Measurement channel is on 1:1 ...
67 views

### How to use current sources correctly

In this simulation the circuit generates a AC signal at "Electrode". Here I am using two SPDT-Switches (Ron = 4 Ω). My first question: Why isn't the signal correctly rectangular? And how ...
2k 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 ...
203 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 ...
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### 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 ...
• 131
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### 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'...
287 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 ...
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### 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 ...
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### Cadence Virtuoso CMOS layout: MIMcap become unrecognised after instantiating a new component

I have a really weird issue with the layout of my design (TSMC 0.18um BCD). I have three components (A, B and C), all of which are LVS and DRC clean and sitting in their own respectable NBLs. ...
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### How to use two or more ultrasonic transducer drivers?

My circuit is below, it has two ultrasonic transducers, transformers and drivers. The transformer is B78416A2232A003, the transducer is MCUSD14A40S09RS-30C, the driver is PGA460-Q1. Digital interface ...
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### How to have sharper rise for ideal filter frequency response in matlab

I am writing about analog filters in my blog and I decided to plot the frequency responses using matlab, representing the responses using step functions. But matlab uses heaviside function which does ...
44 views

### Why is connecting an analog servo distorting this PWM-wave?

I'm working on a project where I'm trying to steer an analog servo using a PWM-wave generated by this circuit. I found the circuit design from this article. It consists of three operational amplifiers ...
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### Verifying the Measurement Precision of a Circuit

My aim is to build an electronic circuit that allows me to measure the relative precision of the energy of optical pulses in the order of 10^-6. The optical power of the laser pulses is measured with ...
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When I look at the waveforms of simulated circuits, how do I know when their behavior (for example flipping value stored on a node, or an unexpected drop in strong level value...) is due to MOSFET ...
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### Sensitivity of Inrush Current Circuit

I'm new to LTSpice and analog design - I'm having a bit of a struggle getting a feel for the behavior of this inrush limiting circuit. Stole the design from another SE post, but playing with the ...
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### RHP pole of two stage OTA

I learnt that for any amplifier (with some capacitor) if we short/open the capacitor and the polarity of gain changes, it is a sign of RHP zero. Now, while applying the same analysis I obsevred that ...
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### Why am I barely able to read the voltage changes with this circuit?

I'm using this EMG sensor to measure the EMG signal from my bicep. However, I can barely read the voltage change from an oscilloscope when my muscle contracts - the output is a horizontal line of 1.5V ...
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### No current changes using INA219 to reading industrial sensor

I intended to use the INA219 chip to read the 4-20 mA current loop of the industrial sensor for the automation project. the sensor voltage is 12 V, my first schematic was as follows: The ground of ...
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### How to measure 10bit SAR ADC 's input Dynamic range after switch 9 time?

I want to know 10 bit SAR ADC , supply voltage 0.5V , Vcm based , after DAC switch 9 times , how to measure DAC input Dynamic range ? I need to know voltage range that I can use Voltage to time ...
135 views

### 16 Hall-Effect Linear Sensors to Analog Muxer to an Op amp scaler to ADC

I am planning out a midi controller because not enough of those exist. Down to my inexperience please point out some gotcha I may be missing. The short version of what I am doing. Basically 16 hall ...
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### Transformer's capacitance

Our main purpose is create the transfer function of a transformer, and we want that for a resonance frequency higher than 1 MHz for our LLC transformer in an LED project. https://www.omicron-lab.com/...
227 views

### 555 PWM circuit set frequency shifting after 2 months

Please refer to post PWM generator circuit review for initial simulation and bugs on the circuit. In general, the circuit works very well and I can control a 12V fan with the PWM output of the 555 ...
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### Passive linear circuit to generate high-voltage spikes from a 10 V peak-to-peak square wave

How to implement a passive linear cırcuıt to generate high-voltage spikes from a 10 V peak-to-peak square wave with a source resistance of 50 Ω with a frequency of less than 5 MHz? Peak value of the ...
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657 views

### Daisy-chaining two ADC with SPI protocol

I'm trying to configure and read two ADCs (MAX11156) with a RaspberryPi. The ADCs are daisy-chained together. For the communication, I'm using python code with the spidev library. The driver is ...
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### Use of a three wire load cell

I am currently doing a project which requires the measurement of forces on a surface and to achieve this we are using 3 wire load cells. The problem that I am running into is no matter how I orient ...
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### Is capacitor voltage coefficient a function of frequency?

I have learned that the value of capacitance in a capacitor can vary slightly compared to nominal based on the voltage across it. This is called voltage coefficient of capacitance (VCC) It is actually ...
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### 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 ...
525 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 ...
380 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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### 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 ...
1k views

### Quality Factor Formula

I read on many books this formula to calculate the quality factor of a series between a resistance and a reactive component (L and/or C): Now let's consider the series between a resistance and a ...
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### ECG / EEG Amplifier design tricks

First of all, sorry, I missed the links / images where I have found the solutions mentioned below (I hope, if you are familiar with this topic, you know them): I have to design an ECG / EEG analog ...
613 views

### Parasitic insensitive switched capacitor circuit

I'm trying to simulate the parasitic insensitive switched capacitor circuit shown here: I am using cadence virtuoso. My input is a sine wave of 1 V amplitude, 0 DC and 1 kHz frequency. I am using ...
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### Arduino mega 2560 Analog max reference voltage

Each time I power up the Arduino, the max reference voltage which is represented by 1023 changes. I observed this by measuring the voltage from the Aref pin each time. Is there any internal function ...
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### 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 ...
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