Questions tagged [signal]

A signal is a stream of information in the form of a varying quantity. Usually in electronics, signals can be in the form of voltages, currents, or radiated electromagnetic fields.

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54 views

What does measuring voltage do to the current or signal of a pin?

I have a problematic digital signal which starts working when I measure the voltage between the pin and ground. What's the effect of a voltmeter on a pin (or to rest of the circuit) when you measure ...
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2answers
60 views

How to convert sensor signal to temperature from the data available from the datasheet?

I have a Pyrometer datasheet showing signal percentage (0 to 100%) with the corresponding respective temperatures (from 0 to 200 °C) and current values (from 0 to 20 mA) in the whole measuring range. ...
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2answers
111 views

Simple 200 feet “Morse Code” Tranceiver [on hold]

TLDR: I'm trying to create a simple 200 feet range "morse code transmitter" (which is legal according to the FCC), which is really just an AM transmitter that can transmit a single frequency tone (...
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1answer
35 views

Detecting signal / amplitude from 2 wire DC speaker

I want to create a circuit that replaces a 2 wire speaker in an existing electronic device. I want the device to be able to trigger an output when the amplitude of the signal that would regularly ...
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1answer
79 views

If I look at a signal in its frequency domain, are there some guidelines by which I can tell how that signal looks in the time domain?

I was studying the Laplace transform and the Fourier transform, and I can't figure out if there is some intuitive way of finding out how a signal looks in the time domain if we know its frequency ...
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1answer
69 views

Tech help with story: Will my radio signal be blocked by a mountain? [closed]

Hoping I can get some help with a technology question for my novel. My protagonist is being pursued, and they have put a tracker in his arm he cannot remove, lest it blow up and kill him. Pretty ...
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1answer
83 views

What to do with ground wire?

I have a few I/p transducers(which work on 4-20mA loop current) and I have made a single cable for all of them, they each have posititive, negative and Ground wires. The controller I have for these I/...
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3answers
174 views

Voltage propagation along a wire

Let's say you have a wire connected to a device that you can switch between high-voltage and ground voltage. The wire is not connected to anything on the other end. You're observing the voltage in two ...
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1answer
90 views

Arduino not outputting square wave with 50% duty cycle

I’m currently using an Arduino and my main goal is to output 2 signals from 2 digital pins. Pin 1 (D7) would output a 1 kHz signal with a 50% duty cycle and pin 2 (D8) would output half of pin 1's ...
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2answers
109 views

Yagi antenna without amplifier, would it work?

I'm in a big hurry to make a 4g (LTE) Yagi antenna (I have the schematics), but i currently don't have an adapter for it. Instead i'll use just the end connection of my coaxial cable (Bending the ...
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0answers
22 views

Combined 25V/OPEN and 25V/0V Input circuit

I am designing a board for digital inputs in which I will be receiving 2 types of inputs, 25VDC/OPEN and 25VDC/0V, 10 inputs each. The input signals have different specs but is it OK to design same ...
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2answers
48 views

Switch multiple contacts in parallel from a single 24V DDC output

I have a DDC (direct digital control) with a 24V digital output and I need to control around 100 external circuits, each having their own input. The switching distance between DDC and remote panel ...
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1answer
45 views

USB bus Differential signals and Pin swapping

USB 1.0 and 2.0 has D+ and D- two differential pins. My understanding is that differential signals are symmetrical so any of the two lines carries an inverted signal of the other line. But in the ...
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0answers
35 views

What is the function of CLKREQ and PEWAKE when those are used in PCIE?

I could understand The CLKREQ# signal is used by the L1 PM Substates mechanism. And PEWAKE signal is used to wake up the ROOT COMPLEX(RC) during the sleep mode. And these two signals are bidirectional ...
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1answer
23 views

Data Lines on VME64 Bus

I am learning about the VME64 bus. It has only 16-bits of data bus on its P1 connector while no data pins on P2 connector. Does it means that VME64 is actually a 16-bit bus?
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1answer
31 views

Pins for VME64 Bus arbitration

I have a board that has VME64 core implemented in it and this board communicates with other boards via VME64 bus. All boards share the same backplane motherboard which has J1, J2 connectors on it. If ...
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1answer
22 views

Bare minimum pins for VME64 Bus

I have a board on which core for VME64 bus is implemented and it communicates with other boards on VME64 bus using only 1 connector (P1, 5 rows, 32 pins on each row, total 160 pins) instead of 2 ...
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1answer
51 views

How to see Signal frequency and Sampling frequency on the frequency spectrum

If I have a 100 Hz periodic analog signal and let us say it is band limited to 1kHz and I sample it at 3 kHz. If I want to see its frequency spectrum then how to differentiate between the signal ...
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4answers
180 views

Question about differential signals as input of an operational amplifier

I'm studying the circuits which are used to implement operational amplifiers. For example, I've studied the two stages amplifier (in which the first stage is a differential amplifier with differential ...
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1answer
36 views

Connecting balanced low impedance output with unbalanced high impedance input

I want to send the signal form my audio interface to the guitar pedal effect. I'll use interface's line out balanced output and plan to plug it in to the effect pedal which has high impedance ...
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2answers
33 views

Practical examples to determinism and periodicity of analog signals?

What I understand from deterministic signal is that we can define it as a function. Same thing is valid for a periodic signal. But periodicity and determinism are are treated as independent categories ...
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3answers
437 views

Don't individual signal sources affect each other when using a summing amplifier?

I am studying the book Electric Circuits by Nilsson & Riedel. There I learned about "summing amplifiers" and how to derive equations by applying KCL at inverting input of the op amp. I see that ...
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3answers
129 views

How to split audio signal into 3 separate channels?

I have been working with the following circuit: to build a audio mixer where you can take multiple line inputs, cd players, computer, phone, synthesizers, etc... and mix them together to a single ...
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1answer
39 views

Baxandall tone circuit passes signal through but does not alter its tone

I added an Baxandall active tone circuit to an existing overdrive circuit and I'm having an issue. The signal passes through the circuit/opamp and out to my volume control but the bass and treble ...
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4answers
108 views

Where does return current flow for a differential signal?

As far as I understand, return current flows the "negative" channel for a differential signal connection. Only if it is not balanced well, there might be unwanted return current in reference GND or ...
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1answer
41 views

Ondulatory routing in Raspberry Pi [duplicate]

I bought a Raspberry Pi and I noticed some of the routings are not straight lines but instead they make a funny ondulatory shape (see picture at the right and bottom of the processor). I'm not sure ...
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1answer
47 views

Use SR 830 lock-in amplifier to detect the second harmonic component with respect to an external reference [closed]

I have a sine wave external reference at frequency f0, which is connected to BNC REF IN. The response signal is fed into input BNC A/I, I want to detect the second harmonic component in the input ...
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2answers
80 views

What is used as a rotary join in Lidar system? [closed]

I want to transfer data between a rotary platform mounting an antenna and a PC, so I can scan for a signal at 360 degrees. I could use a slip ring but there is a loss in signal. I want to transmit ...
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1answer
50 views

Find the total gain from the following Signal Flow Graph

The signal flow graph for a system is given in the figure. Find resultant gain.
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1answer
59 views

Help with wiring OEM LED turn signals that has 2 voltage inputs

The term AFS is used in the 2nd diagram to help differentiate between the bulb type turn signals vs the led type. I'm trying to swap my headlights(without-AFS) to a higher trim version(AFS) on my ...
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1answer
31 views

How do we interpret frequency from fft command in matlab?

How do we interpret frequency from fft command in matlab? When I apply fft to a sampled function(@ Fs) and I get peaks at some values in the fft array. How do I know what frequency in Hertz does it ...
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3answers
57 views

Frequency/amplitude modulation and SNR

I read (for instance here) that FM modulation is less affected by noise than AM modulation. But I don't understand conceptually the reason for that: why is the SNR with frequency modulation higher ...
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1answer
61 views

Envelope detector for AM signals

How or what are the constraints for deciding factors of envelope detector for AM As far as I know that charging time of capacitor should be below 20T where T is periodic time of carrier and ...
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2answers
473 views

Square wave to sawtooth wave using two BJT

I have two circuits that are supposed to be square wave to sawtooth wave converters: Both circuits receive a positive square wave as their input and generate a positive sawtooth as their output. Do ...
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3answers
60 views

VCO circuit Analysis

can you help me with the basic comprehension of this Voltage Controlled Oscillator scheme (it was used in a PLL)? I do not understand why there are two varactors instead of one, and the role of the ...
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1answer
43 views

How to measure RSSI of bluetooth devices on PC

I'm a student in highschool doing research for a science project. I want to measure the RSSI of bluetooth devices on my Windows PC. I've searched on the internet for around 3 days but found no success....
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1answer
32 views

Minimum Shift Keying

"Overall frequency excursion del-f in MSK is minimum frequency spacing between symbols 0 and 1 that allows their FSK representation to be coherently orthogonal". What is meant by being coherently ...
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0answers
55 views

Phase, Frequency and Laplace transform

I have a doubt on the relationship between phase and frequency. We know that the definition of angular frequency is: ω(t) = d(\$phi\$(t) / dt, where \$phi\$(t) is the istantaneous phase of our ...
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0answers
21 views

Foster - Seeley FM Demodulator Explanation

Consider this Foster Seeley Demodulator If I have correctly understood, its basic working principle is the fact that at the secondary coils (L2) of the Balun there will be two signals equal and ...
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1answer
62 views

PLL (Phase Locked Loop)

I find a bit of confusion on the web about the use of the PLL. Sometimes I read that, given a certain input signal, it is used to generate a signal whose frequency is N times that od the input one, ...
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3answers
41 views

How to make a differential measurement using two single-ended circuits that are high-z isolated?

Consider this system: There is an AC source that is differential w.r.t to ground. To measure this signal, I setup a diff-buffer and then feed the output to an ADC which measures the differential ...
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2answers
65 views

Double Balanced Mixer

Consider this double balanced mixer: Its output contains only the frequencies generated by the product of those of LO and RF signals, where LO is supposed to be a large signal (which switches ON and ...
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2answers
52 views

Powering condenser mic while getting the signal

http://www.afrotechmods.com/groovy/amplifier_tutorial/amplifier_tutorial.htm Look at the extreme left part of the circuit above seem to power the mic by 9v through a 5k Ohm resistor that powers the ...
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1answer
60 views

Filter Design (Low Pass Prototype Method)

In the Low Pass Prototype Method for filter design, after choosing the order N and the tolerance of the filter according to the design specifications, we have to look at some tables with the ...
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0answers
39 views

Old motor with unknown pulse generator signal

I have been building a new controller unit for a ~20 years old gate opener because it was never reliable, and eventually stopped working entirely. So far, I have got everything working except from ...
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1answer
92 views

How can I vertically shift the voltage of a zero-centered signal such that I can read it with the Teensy 3.2's internal ADC? [duplicate]

I have a sinusoidal signal with a frequency of 100 kHz. It's zero centered with a peak-to-peak of around 3V (i.e. from -1.5V to +1.5V). I want to be able to read the peak-to-peak voltage with one of ...
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1answer
57 views

Can the FTDI Tx and Rx tension level be different that it's VCC?

I'm building my own FT232RL to convert a UART signal to USB. The source of power will be the USB 5V, but for reasons of the circuit i already have it would be easier to let more of the circuit keep ...
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1answer
39 views

Rat Race (Hybrid 180°) Scattering Matrix

why the S matrix of a rat race is the following one? Which is the reasoning for determining it?
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2answers
117 views

Sawtooth signal

I'm trying to create a sawtooth signal using low cost pasive and active components. This will allow me to compare it to an analog signal to output a PWM signal. My sawtooth signal have to be at least ...
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3answers
727 views

Do I need to maintain source of a signal till it reaches the destination?

If I send a signal through a wire having delay of 10ms, then should I need to maintain the source of the signal till it reaches the destination or can I change after, say, 2ms and send the next signal....