Questions tagged [negative-voltage]

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2answers
120 views

How to get negative voltage?

There's a bunch of posts about this, but they're all for very specific scenarios. I'm a newbit, and some components, like op amps, require both a positive, and negative voltage. But how do you get ...
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2answers
49 views

Trying to understand negative voltage generation with capacitors and diodes

I want to generate a negative voltage from a possitive rail. To do so, I'm reading this article. Here is the schematics it is depicting, assument the input step is +10V: I understand that when the ...
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1answer
22 views

Vestax PMC-07 Mixer PSU

I'm trying to fix a Vestax PMC-07 Mixer and I'm puzzled by the schematics. It is fed by a single +12V wall-wart switching adapter through a DC Jack. Can this configuration really produce a negative ...
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1answer
36 views

How can i generate a negative potential/current and alternate the pin-input between positive and negative potential/current using an arduino uno?

My goal is to make the barmagnet rotate by activating two coils and use both forces at the same time with an Arduino Uno. One coil should have a positive potential or current to attract the negative ...
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1answer
72 views

Virtual ground concept in electronic circuit

This is my current sense circuit that I connect to Arduino in order to measure how much current a load draws. As you can see at the bottom of the image there is a -5 V voltage source connected to the ...
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1answer
100 views

Is there any way to have a diode that have very small resistance from reverse path?

I'm trying to find a way so I will always have close to 0V at the measurement point (above the diode), when I have 0V as input. ...
0
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1answer
63 views

How to adjust/vary a negative voltage

I'm in the process of building a bench top power supply, based on an ATX PSU. I have nearly finished the build and have a unit which can supply +3.3 V, +5 V, +12 V and a variable voltage between +0.8 ...
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3answers
69 views

What is the problem with connecting a negative voltage to an op amp's negative lead while the possitive one is grounded?

I'm reading a manual on op. amps that presents the following schematics: And says: [Context: Vin goes from -0.1V to -1V] When Vcc is powered down while there is a negative voltage on the input ...
2
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1answer
253 views

Discrete negative voltage regulator oscillating under load

I'm trying to save a few volts voltage drop and use a discrete voltage regulator, having a feedback doesn't really matter because the current draw is very low. In the diagram below, if I remove C2 ...
0
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1answer
33 views

Using a switch detect IC with negative voltage

I am designing a circuit where a negative voltage signal can have multiple levels, eg -12, -8, -6 depending on the circuit state. I am looking at several switch detect ICs such as TI's TIC12400 that ...
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4answers
577 views

How do you calculate negative and postive voltages in a grounded circuit?

This may be a vintage question, I'm not sure. I am self-studying electronics using some old books and came upon the problem below from "Basic Electronics" by RCA Institutes, 1965. The book ...
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0answers
33 views

How does this -ve power supply work?

This data sheet (linked from the product page of Rapid p/n 61-6211) covers an adapter for LVDS displays, that can provide various different voltages. This includes a 'VGL' signal that is set at -6.8V. ...
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1answer
78 views

Pulling down positive voltage to limit negative voltage current

Below circuit is the negative rail of a dual tracking power supply. How do I detect voltage drop on Node1 and pull down Node2 to limit the current without using an op-amp? Edit: I just want to define ...
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1answer
56 views

Problem with a tracking LM337 stability

I'm building a dual rail tracking power supply, for the negative supply because the current is not going to exceed ~200 mA I decided to use LM337 both for simplicity and stability of the circuit (so I ...
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2answers
48 views

4BIT DAC has negative voltage at op amp output

My school task was to simulate a 4BIT DAC converter in multisim. Im supposed to simulate the circuit when the switches are on/off and measure the output on the op amp. I think the circuit works fine ...
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2answers
173 views

Modifying SMPS power supply to produce a negative voltage

In SMPS power supply that uses a single transistor to generate the switching signal ( no control IC), which component must be modified so the output voltage could be negative? I tried to reverse the ...
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1answer
62 views

-30V power supply for HTS6520

Story Received a Philips HTS6520 for free however the subwoofer (and remote) is missing, no cables at all, so unable to use it because the sub also provides the power (read on to see what I have done)....
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1answer
94 views

How is the -3.3VA voltage in this circuit generated

I understand the +3.3VA, but I don't kown how the -3.3VA generated?
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0answers
32 views

Dividing negative voltage source with three cables - What should one do with GND?

I have a sensor with an output between (-10 V, +10 V) and three analog out cables: Sensor(+), Sensor(-) and Sensor(GND). I want to scale down the signal to (-2 V, +2 V) and feed it into an ADC. I ...
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0answers
36 views

Switching load with changing polarity

From a bespoke board I'm receiving 18vdc that I need to switch. This 18vdc will usually be +18vdc but at times can be -18vdc. The load is .35A. The polarity is being changed via a H-Bridge and ...
0
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1answer
114 views

Inverting boost converter by using MC33063A/MC34063A: Where does the IC get ground connection?

I want to design an inverting boost circuit by using MC33063A. I want to generate -5.75V from a +5V supply. My question is, how does the IC connect itself to the ground? The 4th pin is the ground pin ...
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2answers
975 views

Does 7905 needs minimum load current?

In the 7905 negative voltage regulator datasheet, it didn't mention that it needs a minimum load current to operate. The 7905 that I have is outputting -7 V but adding a ~2 mA load causes the voltage ...
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1answer
87 views

Can a transistor send negative voltages when used as a switch?

I have used relays as a switch in order to turn on and off things. This is how I do it: My IC is my integrated circuit call it arduino. With a small current I am able to turn on and off things and I ...
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1answer
42 views

Some doubs regarding AC/negative voltages in an audio signal

I know that audio signals are AC signals (negative/positive voltage). Assume a typical Fuzz (guitar pedal) effect circuit below. It seems signals stay between 0 and 9 V (9V is the power/battery ...
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1answer
75 views

Two power supplies with different current in series

Does the schematic in the picture work with these powersupplies from China? Both are rated with 5V but one with 20 amperes and the other with 2 amperes. https://www.aliexpress.com/item/33042313383....
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2answers
45 views

Problem with wide voltage range CC sinking

I want to sink ~10 mA of constant current at wide range of voltages even lower voltages like 10 mV, below circuit suggested to me in one of my older questions: simulate this circuit – Schematic ...
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1answer
119 views

'Inverted' voltage follower with an opamp

I'm trying to figure out how I can achieve an 'inverted' voltage follower. That is if I'm feeding 1V I output -1V, if I feed 2V, -2V etc. I'm only going for positive tension to negative, I have +15 ...
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0answers
52 views

What voltage range will I need for my multiplexers?

I'm trying to make a Fuzz guitar pedal effect (for a guitarist in the bands I play in), and I found this one: The Fuzz of 1000 Faces Made by Randy Randofo. Below is the circuit from that site: I ...
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1answer
84 views

Power Circuit to Subtract a Voltage by a Known Amount

Using a charge-pump it's possible to add voltages together (i.e. source 10V + PWM 5V = 15V, ignoring diode drops) simulate this circuit – Schematic created using CircuitLab Surely there must ...
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1answer
63 views

DIY op-amp power supply

I purchased a DIY op-amp kit from eBay. The parts arrived in a baggy, I soldered it all together, but have no idea how to wire the power supply? I am hoping to use 9V batteries, and realize I might ...
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1answer
77 views

Advice on generating a negative supply rail (-5V) in an embedded, mixed signal design

I'm designing a board that can take an input DC supply of between +8 and +36V DC (+12V nominally) and needs rails of +5V, +3.3V, +2.5V and +1.8V. My current design uses a step-down regulator (LMR23625)...
0
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1answer
61 views

BJT - finding Ic with two opposite voltages connected to base

Here's a question from my homework: Find \$ I_C \$ and \$ V_{CE} \$ for the circuits below, assuming \$ |V_{BE}| = 0.7V \$ and \$ \beta = 100 \$. I understand circuit (a), but for (b), I don'...
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2answers
291 views

Logic Level Converter for Negative Voltages

Here is logic level converter mostly used for converting signals between 3.3V and 5V. (Other positive levels such as 1.8V are also possible). What if I want to convert from 3.3V to -5V logic (negative!...
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1answer
65 views

Positive-negative voltage from dual supply

I'm trying to build a low cost hifi (Hiraga Le Monstre) but I have two old computer PSUs at hand so I tried to use it as power source. The Monstre needs +12V and -12V, computer PSUs have both, but the ...
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4answers
190 views

Stepping up from 12vdc to 100vdc/-100vdc

I am looking to power a phone ringer circuit that requires +100 V DC and a -100 V DC. I have found a circuit here but this converts it to 120 V DC with a transformer. Is it possible to get +/-100 V DC ...
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1answer
137 views

Is it possible to make a ±3.3 power supply from 9V battery?

I am trying to make a little audio amplifier with a ±3.3V power supply I and would like to power it with a 9V battery. Is there a solution to this? simulate this circuit – Schematic created ...
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2answers
404 views

Negative voltage from multi-tap transformer

If we have a multi-tap transformer like this: Is it possible to use two of the taps to generate negative voltage and use other taps for positive voltage?
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1answer
53 views

Constant Offset Floating Supply

What circuits can be used to provide a voltage supply capable of sinking around 1A of current that will always float 10ish volts below a given supply, that could be from 12 to 200 volts? I have ...
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1answer
77 views

How to generate positive and negative power supplies from a single supply with high current driving capability?

I am trying to build a 1553 military standard bus transceiver (analog front end) and I am required to use a single power supply of 3.3 V. To be able to receive, my comparators need supplies of +/- 3.3-...
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0answers
45 views

Generating high current negative supplies

I'm trying to generate a high current negative supply (30A, -2V). This is to be a negative symmetric supply along with a (30A, +2V) rail, with an actively driven ground which I need to be system ...
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3answers
158 views

Non-inverting amplifier with negative supply rail

simulate this circuit – Schematic created using CircuitLab The formula Vout = Vin * (1 + R2 / R1) is not valid for this case? because for example I'm feeding ...
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1answer
70 views

Creating an low current negative voltage

Good evening, This is my first post on this forum, so if I'm doing something wrong don't hesitate to tell me. Now to my question; I need 2aa batteries or an LiPo battery(3v-3v7) to be boosted to 5v(...
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1answer
195 views

Increasing output current of the inverting voltage doubler charge pump circuit, implemented with MAX1720

I have a +3.3V voltage rail available. And I want to generate a pair of negative and positive symmetrical supplies out of it. The magnitude of the output voltages must be less than 7V and should be ...
3
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1answer
1k views

Generating negative voltage rail using P7805 DC-DC converter

I need to create a negative voltage rail (from positive supply rail), say -5V to keep a P-MOS transistor in ON-state even when the voltage on its [S] source is 0V. So I found this schematic in an ...
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4answers
3k views

How to make a simple negative power supply

I want to experiment with amplifiers but I need a negative power voltage source. I looked for some circuits but as far as I found they either are not simple & reliable or require an IC. Is there ...
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2answers
85 views

Splitting plane for negative power supply

I used op-amp for my project and supplied with +12 and -12 volts. My PCB will have 4 layers which are TOP (signal layer), POWER (internal plane), GROUND (internal plane), BOTTOM (signal layer). When I ...
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0answers
79 views

Bipolar transistors that only connect via base to emitter

I am trying to understand how to use this configuration of the LTC2992 power measure IC and the only part I am confused with so far is the two transistors which I have circled. What I know so far ...
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2answers
325 views

Negative Voltage Output From Capacitor

Circuit Link I am very confused about negative voltage in capacitor, it can even light a led as you can see in the circuit. My questions are; 1-Why capacitor gives ~-2 V in its negative terminal ...
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1answer
138 views

LM2776 gets damaged after some time

It is almost the reference design from the DS. The only differences are those quite large inductances I had to add to remove the noise. The neg voltage is used to power RR OPamps feeding the ADC the ...
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1answer
131 views

Inverting negative voltage back to positive with LM324

To be able to measure the value with an Arduino Nano I want to convert the negative rail voltage to positive. I tried to build a simple inverting amplifier with unity gain using LM324. The supply is +/...