Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [log]

For questions about logarithms (log axes such as on Bode plots, log scaling, etc.). Use "log-amplifier" for log amplifiers instead, and do not use for logging data. Consider also using "math" and/or a related plotting tag such as "bode-plot", if applicable.

For questions about logarithms (log axes such as on Bode plots, log scaling, etc.). Use for log amplifiers instead, and do not use for logging data. Consider also using and/or a related plotting tag such as , if applicable.

13 questions
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How can you turn perceived brightness (log scale) into a linear analog output using an LDR?

This question is not about how to make illuminance (in lux) a linear function of voltage! It's about linearly representing the human perception of brightness, which itself scales logarithmic to the unit lux and is not equal to lux. TL;DR: How can…
Niklas E.
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6
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3 answers

Log - Log Graph: Minor Increments Between Decades: 8 instead of 10 with spacing non-monotonically decreasing

Inolux uses (in its datasheet template for each of its LEDs) a log-log scale to depict the Relative Luminous Intensity, but it's not depicted in a manner that I've witnessed before. For example, IN-P32TRRRGB: From the datasheet: There are 8…
kando
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4
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2 answers

Can I compress the dynamic range of ns pulses to better fit ADC range using log amp or mixer?

I have an experiment in which the signal I want to measure is a 1 ns pulse that occurs somewhere around 0-100 ns after a trigger. I want to digitize the pulses to extract the time they occurred and the amplitude. The problem is the amplitude of the…
argentum2f
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3
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2 answers

How do you convert dBm to Vrms?

I'm trying to convert dBm to Vrms. The formula for dBm is \$ dBm = 10 * log(P1 / P0) \$ where P0 = 1mW so \$ +13dBm = 20mW \$ If I convert this to a voltage using the formula \$ P = Vrms^2/R \$ where R = 50 ohm, I find that \$ Vrms^2 = 20mW *…
timsweeney7
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3
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4 answers

Why does my diode log amplifier in LTspice not match theory?

I am trying to learn about analog multipliers, and I'm trying to implement one using a log-antilog design. I am currently having some difficulties with the log part because simulating an ideal amplifier gives results that are consistently about 0.4…
Paolo Celati
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2
votes
3 answers

Valid or invalid logarithm operation?

Is the following operation valid or invalid? The question is to calculate receiver gain and this is one of the steps I got confused. The receiver sensitivity is given -45dBm and transmitted power is 70dBm. 70dBm - (-45dBm) = 115dB. So, 70dBm + 45dBm…
eldenlord9394
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1
vote
2 answers

Potentiometer on max. resistance at lowest setting (off)

first question ever here: I'm struggling with a 10K log potentiometer in an EQ. When at lowest CCW setting it's the same value as on full CW pos. Is this typical when a pot goes bad or is that fixable? update: Thanks for the advice! I'll change the…
jackaudioslave
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0
votes
1 answer

How to calculate the 3dB frequency from an oscilloscope using Logarithmic sweep?

How do I calculate the 3 dB frequency from an oscilloscope reading using a logarithmic sweep? I made the mistake to use logarithmic instead of a linear sweep and now my data doesn't hold for the formula…
User626
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0
votes
1 answer

Logging and retrieving large bursts of sensor data from an Arduino

I was wondering, if I put an Arduino with a few sensors on let's say a water rocket to track acceleration and height and what not, how would I save this data? I'm assuming that I want to have a high resolution in my data, so let's say I take a…
Christopher
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0
votes
4 answers

Values between log scales in a graph

I have a LED voltage vs current graph. The forward current is represented in a log scale. Suppose my value is 120mA. Where should I place my point and what would be my forward voltage with respect to the below graph? Like, should I split the box…
user220456
0
votes
2 answers

Plotting a bode gain plot with the slope in Excel

I am not an expert in Excel, and therefore, I want to know if there is a way of including the slope (dB/decade) in a bode gain plot in Excel or any free software (that allows to first input the frequencies and corresponding gain in dB, and then…
William
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0
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2 answers

I don't know whether HD44780 LCD is correctly initialized in Proteus

I'm trying to control an HD44780-based LCD in Proteus with 4-bit interface. The problem is that the simulation log gives me a series of messages, which I think means that I'm not sending the commands for initialization correctly. The initialization…
vram
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1 answer

Understanding log-log axes

In below picture there are two graphs representing the function \$H(s) = s-z_1\$ (assume \$z_1=2\$ is a constant). The left graph has \$\omega\$ on x axis and \$\|H(j\omega)\|\$ on y axis. The right graph has \$\log\dfrac{\omega}{\|z_1\|}\$ on x…
AgentS
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