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

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Combine two signals of different frequencies in a test setup

I have a device that is powered from a current source. The current source supplies 10A at 60Hz - the magnitude is roughly 5-10VPP. I would like to inject another signal on top of that to simulate ...
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1answer
52 views

Digital light organ

I am trying to make a circuit that takes an audio signal from an MP3 player and converts the signal into digital signals based on frequency. Audio In is the is the signal from the audio jack of an ...
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2answers
53 views

Looking for OP-Amp with good rail to rail performance, 5V to 0V [closed]

There are thousands of OP-Amps on Farnell's website, so I thought asking the stack-exchange community might be a good idea. I am looking for an OP-Amp for use in my project. I currently have an ...
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0answers
45 views

Ground Plane, Bypass Capacitors and Differential Pairs

I've placed a KSZ9031MNX Ethernet PHY on my board, and am now trying to get power routed to it. The digital side will merely be annoying to do, I think, but I'm at a complete loss on the analog side. ...
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1answer
61 views

How does digital patch memory work on an analog synthesizer?

Not an electrical engineer, but kicking around ideas for a polyphonic analog synth with digital memory, a simplified/modernized update of an older all-analog design. I've riffled through some of the ...
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1answer
143 views

What is the simplest analog circuit for integer addition modular 2?

This probably is a rudimentary question. I would like to have a simple analog (switch) circuit for addition modular 2, or \$a_1+a_2+\cdots +a_n \$ (mod 2). Certainly, digital transistors can ...
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2answers
91 views

Help understanding PIR amplifier analog circuit

I found a PIR amplifier circuit and would like to understand better how/why it works. The purpose is mostly to learn more about analog electronics. I found the following circuit here: PIR motion ...
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1answer
49 views

Bluetooth Module with Analog Input

I'm building a wearable Bluetooth device. When a button is pressed on the device, it sends a signal to the user's smartphone and consequently an app on said phone. I'm an app developer with no ...
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0answers
83 views

Should my external analog input be isolated?

I want to build a device that samples analog signals from various measurement instruments via their analog outputs. The instruments have their own power supply, and all devices are powered from the ...
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3answers
83 views

Transistor resistance for switching analog signals

I would like to use two transistor to switch on/off two paths to an ADC input so that only one path is active at a time. Is this a bad practice? I'm aware of analog switches but don't know if ...
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4answers
713 views

Is the only way to drive a speaker with a positive and negative rail?

I want to create a simple sinusoidal oscillator (Wien-bridge with soft limiting), connected to a high gain amplifier. I don't have much experience with audio, but I'm guessing a speaker needs a ...
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3answers
82 views

1:1 and flyback transformer at low frequency and high temperature

I am designing a circuit in that I need 1:1 and fly-back transformers at low frequency (0-100kHz) and high temperature. Can anyone help me with these? I am looking for voltage being handled around ...
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0answers
72 views

Digital Latch Circuit with Unknown Outputs

Introduction I am a student currently enrolled in a digital course course. I'm actually an analog kind of individual so I (like most other analog people) have a hard time understanding logic. ...
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0answers
45 views

How to bias a MOSFET folded cascode transistor using a cascode current mirror?

In the given picture how the folded cascode present at the output is biased. The method used by the author is direct voltage source biasing, but I wish to use a cascode current mirror but facing a ...
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3answers
86 views

Voltage range shifter from 0V to 3V to -/+1.5V

I'm trying design from scratch (discrete components and opamps) a circuit that could linearly translate from 0V to 3V range to -1.5V to +1.5V. Can someone provide suggestions and designs of how to do ...
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0answers
57 views

State Variable Filter analysis

I'm in the process of making my own adaptation of the classic State Variable Filter (SVF) in the analog domain. Reading up on this article. I discovered that they use superposition to get the ...
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2answers
96 views

MOSFET behavior with small load resistor

I'm trying to understand the behavior of a MOSFET I got at radioshack (Fairchild IRF510). I have the circuit set up in the way recommended by the datasheet: The specifications suggest that it ...
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1answer
82 views

Analog temperature sensor with 100mV per 1 degree Fahrenheit

My devices only measure analog precision to the nearest 100mV. Most temperature sensors I can find only do 10mV per degree precision. Currently I'm using the LM34. Is there such a thing as an analog ...
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3answers
164 views

How to know whether the bandpass filter is stable

I am designing a bandpass filter using MFB. However, I do not know whether my filter is stable or not. Can anyone give me some criteria or methods to evaluate the stability of the filter design?(still ...
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1answer
40 views

Three-level analog output (Ground, 2.5V and 5V) - DAC good enough?

I'm planning to replace the thermostat of my evaporative cooler with a Raspberry Pi plus some control (see Wiring a 24-volt Swamp (Evaporative) Cooler for Control With Relays). Signaling from the ...
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5answers
151 views

How electrical signals converted into Digital (binary 1 0)

I already ask this question in yahoo and in Microsoft........they say that : did I mean to say how to convert analog signals to digital signals.....and they suggest me the theory of AD converter So, ...
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1answer
214 views

Reducing Undershoot and Overshoot in a custom voltage regulator?

I'm trying to build a voltage regulator that takes in a reference voltage and an unregulated voltage (to power the components, and this voltage is always greater than the reference voltage) and ...
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2answers
126 views

How can I add three AC signals?

I have three light sensors which outputs appropriate AC currents with respect to light intensities. I only have one pin left for my ADC IC that I have on my board so I can't sample three sensors using ...
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2answers
68 views

Why does the “top” transistor in a cascode not set the current?

This has been bothering me for some time. Why is it that the overdrive voltage of the bottom transistor in a cascode controls the DC current, and not the Vgs of the top transistor? Similarly, in an ...
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3answers
447 views

Understanding a circuit for reading current passing through human bodies

I found on Instructables this circuit that is used to detect when two conductive pads are touched at the same time by a person (or, in that particular example, a chain of people). Used in ...
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43 views

How to find bias so that OP amp output range is max?

I have a question about (d): I just know that the maximum output may be \$V_{BP2}+|V_{ov7}|\$ and that the minimum may be \$V_{BN2}-V_{ov9}\$. Can anyone help me? By the way, I want to check the ...
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1answer
62 views

Field programmable analog array

I know and use FPGAs quite a lot between my microcontroller and external interfaces and learned to value the flexibility of this setup. Now I am wondering whether such a thing exists for the analogue ...
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2answers
65 views

In logic levels, why are both the driver and receiver needed?

Here is what my textbook has to say about logic levels: The mapping of a continuous variable onto a discrete binary variable is done by defining logic levels. [...] The first gate is called the ...
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1answer
73 views

replacing DIP switch with Analog Switch

In order to minimize the number of components for measuring different types of signals(Resistance, Voltage, Current, ETC), I have designed circuit using DIP switch which the user can turn on and off ...
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4answers
630 views

How are positive and negative feedback of opamps so different? How to analyse a circuit where both are present?

In an opamp, feedback on the positive input places it in saturation mode and the output is of the same sign as V+ - V-; feedback on the negative input places it in "regulator mode" and ideally Vout is ...
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1answer
71 views

High-gain feedback amplifier design using ADA4004

I am trying to design a feedback amplifier with ADA4004. My desired gain is about 42dB@2kHz. Is it possible to design a stable amplifier with such gain using ADA4004? The ADA4004`s GBP is 12MHz. The ...
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2answers
66 views

Need an extra pin to control my driver board

I've been searching for a way to add an extra pin to a driver board. The MCU board that i'm using only has 8 pins on the left side and i'm already using all of them. 2 are for powering the driver and ...
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6answers
1k views

Is a square wave still considered DC?

Say I have a logic-level square wave, where 0V is "low" and 5V is "high". I'm pulsing this at a constant 60Hz, 50% duty cycle. My intuition says that since the voltage never goes negative, it's a DC ...
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67 views

Utility of Field Programmable Analog Arrays

The only FPAA-related question I can find is THIS, but it doesn't really introduce me to the area. The concept seems like a nifty thing to have as part of an analog toolkit. I can't necessarily ...
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1answer
113 views

Can I set thresholds for 74HC14N (6 NOT gates)? and use as schmitt trigger

I'm trying to convert sine-like wave from IR sensor(quadrature wheel encoder) into square one. Can I make it with 74HC14N(set some fancy RC configuration) or should I use op-amp configuration to be ...
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1answer
43 views

dark current of PIN photodidoe

I am now learning about the dark current of PIN photodiode and wonder that if no reversed bias voltage is applied to the photodiode, whether the dark current is 0 or not? If not, how small it would ...
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1answer
75 views

See if signal is amplified without an oscilloscope

I'm an electronics newbie, but I've had some experience with oscilloscopes in college lab. However, I need to design and wire a simple circuit that can read values from an electret mic. Since the ...
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2answers
126 views

Designing a voltage follower that can provide up to 5A of current to a load

I'm trying to dabble in analog circuit design, but I honestly am a complete newcomer in this area as my strengths are in CS. Sorry if this question sounds stupid, but can anyone help me with designing ...
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137 views

Reading sound with BeagleBone Black

I have a BeagleBone Black and I need to compare sound on two different microphones. BeagleBone Black does not have audio input, and I believe the audio cape only has a mono microphone input. Is it ...
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2answers
309 views

How to design a 4th/6th/8th passive low pass filter?

I am trying to design a 4th/6th/8th passive low pass filter. The filter is used after a DAC to generate a fixed frequency sine wave. The DAC will export a square wave at 1kHz. So the pass band of the ...
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1answer
19 views

ADuC812 needs DAC value written twice. Is that normal/common?

A while ago I had a project that involved Analog Devices ADuC812 microconverter. Amongst assorted on-board hardware, the device had two very helpful DAC converters, that could source 0-5V on their ...
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3answers
49 views

Low power Analog signal Isolation

In my project, the current budget is very tight. With less than 1mA, I have to isolate sensor's signal voltage and be able to measure it with ADC on the other side of the isolation barrier. What I ...
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39 views

Low voltage inverter for low voltage AC

What would be the proper method of making a low (4.2) voltage inverter to get something like a 4.2V AC current?
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5answers
207 views

Can I see an analog signal with changeable frequency on oscilloscope?

I have a sinusoidal signal with changeable frequency (which implies that it is not periodic). I wonder is it possible to see it on oscilloscope? Does it show non-periodic signals? As it is apparent my ...
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1answer
92 views

Isolate two Arduino analog inputs

I have a stereo VU meter. (Audio in on Arduino pins A0 and A1 and GND to common GND also 32ohm resistors going to GND on A0 and A1 to simulate coming speakers) Now my problem is software architecture ...
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2answers
82 views

Multiplexing signals of two wires of a BNC cable and transmitting over a single wire

Background: I have a normal CCTV camera (650 TVL) . It requires a BNC cable in order to feed video signal from camera to DVR. Problem The problem is I have only a single copper wire from CCTV to DVR. ...
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2answers
87 views

Coil-less AC-DC line regulator

I'm trying to fix an AC-DC line regulator that I have build and doesn't work as expected. I'm trying to convert AC 220V mains to DC 5V 10mA without a transformer. To do this I'm using an 1uF 250VAC ...
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1answer
96 views

Put a DAC at the output of FPGA

I have designed a circuit by System Generator to implement on FPGA. The output signal is a sinusoidal with changeable frequency. I need to read the output signal by oscilloscope. I should put a DAC at ...
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3answers
156 views

What is the name of this circuit in English?

I hope that this is the right place to ask this question. English isn't my first language. So here is my question. If you are familiar with analog circuits you know about power amplifier. Here is ...
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1answer
54 views

simple directional audio capturing

In my project I use electret mic + opamp to capture audio, which is later used for speech recognition on a remote site. This works well when operates in a silent environment, but not when there is ...