Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [negative]

130 questions
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How do you visualize negative Frequency in Time domain ?

In the field of Digital signal processing I have seen people using words Complex signals and Negative frequencies. For eg. in FFT Spectrum. Does it really have significant meaning in the time domain or is just a part of the mathematical…
rahulb
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How to supply a negative voltage from a simple battery or psu?

I am using an op amp (741). I need to supply its pin 4 with -5 volts using a power supply unit from a computer or from a simple battery. How am I going to do that?
Neigyl Noval
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Why is the negative contact in a battery bay always the side with some sort of spring?

Is this just purely convention, or is there some kind of technical reason behind it?
wwaawaw
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Op amp analysis: when are the "negative feedback rules" applicable?

When we build op amp circuits that use negative feedback, like so: ... we can analyze the circuit very easily, by assuming that $$v^- = v^+$$ due to negative feedback (when also assuming the op amp is ideal, of course). Besides the obvious…
exscape
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8
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Using two regulators to create new ground: How do I calculate needed power?

I'm thinking of using two regulators to create a ±5 V power supply. I'd use a 10 V regulator and a 5 V regulator and use the 5 V regulator's output as ground for the circuit and 10 V regulator's ground as the -5 V. Something like this: What's…
AndrejaKo
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What happens if I apply a negative voltage across a Zener?

I have the following circuit (just the input portion of a larger circuit): The 6V is coming from a wall wart or other 6 V source. The Schottky diode (UPS120) is there to guard against the input voltage coming in at the wrong polarity. The output…
tcrosley
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Converting/scaling a voltage range ([0v - 5v] to [-5v - +5v])

Can anyone explain how one would convert one voltage range to another? I'm going to need to convert a range of 0 to +5 volts into a range of -5 to +5 volts. How would this be accomplished? Thanks!
Greg
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Negative Voltage

I understand that negative voltage is relative to ground so -5v means 5v below ground, But, if in my case ground is earth, does that mean that -5v will draw 5v from a device. What will happen if I plug a 5v LED into -5v? If I Had this: …
Sasha
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Can I use an op-amp to supply itself a negative voltage?

For my project, I am using an LM324. According to the datasheet, its power supply can either be +/- 16V or 0-32V (max). The output will range from -3V to +3V (or there abouts), so I realise I'm going to need a positive and negative voltage supply.…
Tom
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What kind of circuit is it (negative voltage generating)?

What is the name/type of this negative voltage-generating circuit?
user79839
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Generate +/- voltage outputs using two boost converters?

I am working on a project to power some audio equipment that requires +/- 15V DC. Output current load is about 250mA, maximum. I am wondering if there’s any reason I couldn’t create this using two switching boost converters and a DC wall wart, as…
seagull48
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Measurement of negative DC voltage

I want to measure -30Vdc up to 0Vdc using a microcontroller. I'm basically measuring a voltage source with an output current of upto 2A. I need to bring the voltage up onto a scale of 0V to 5V so that I can use the ADC of my microcontroller. I…
MavenMerkel
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What's the point of a "flipped" opamp power supply (going from -9V to GND)?

I was looking at the attached schematic and realized that all opamps and transistors are "flipped" in respect to their power pins. I realize that this is only another way of writing the same thing with +9V on the positive rail and GND on the…
user35474
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Okay to have both negative and positive grounded equipment at same site(location)?

We have a radio comms site with multiple equipment. Originally the site was set up with a positive ground at the rectifiers. We have some new equipment that is powered from the rectifier shelf, that will not work well with a positive ground. We were…
user32763
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How to limit negative voltage on uC input pin

I'm trying to design a pulse induction metal detector to increase my EE skills a little bit. I started to sketch out the transmitting stage, which is just a MOSFET that switches current through a search coil and limits the back-emf for further…
sled
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