Questions tagged [negative-voltage]

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1answer
66 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
29 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
64 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
37 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
55 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
33 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
46 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
46 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
65 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)...
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1answer
52 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)...
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2answers
65 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
60 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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2answers
68 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
107 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
96 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
58 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
44 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
125 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
51 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
83 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 ...
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1answer
932 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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3answers
1k 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 ...
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2answers
81 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
77 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
162 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
92 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
53 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 +/...
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2answers
252 views

Negative Voltage creating Sinking Terminal

For powering a RS485 circuit, I am requiring a Negative Power Source. I was thinking to split a standard power source with 0V, +6V and +12V, using the +6V as ground with LM7805, and using some LM7805|...
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1answer
114 views

Connecting negative terminal of DC power supply to negative terminal of other DC supply

I'm wiring up an electrical box that has several sensors, relays and a PLC. The PLC and relays are powered with a 24Vdc power supply. The sensors, which provide an analog input to the PLC, are powered ...
1
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1answer
95 views

how to choose a dual power supply for rail to rail amplifier?

I need +15VDC and -15VDC dual supply for rail to rail supply of op-amp. I have found buck-boost inverters used for this task. I have a doubt whether the inductor in the buck-boost inverter circuit can ...
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2answers
360 views

Negative Voltage In Capacitor When + Side Is Connected To -

Hello, i just didn't understand that why we get negative voltage(-4.7V) from capacitor's negative pole when we apply 0V to capacitor's positive pole.As i figured out, this is used in transistor flip ...
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1answer
136 views

Logic gate on negative signals

I need a logic gate to check if A or B or C is negative voltage (referenced to the ground). It does not matter if the output is positive or negative logic (as long as it is in positive voltages) Does ...
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2answers
201 views

Finding the negative feedback loop in the amplifier circuit

Today I was learning about the negative feedback in the amplifier circuits and some quick ways of discovering whether a negative or a positive feedback exist in the circuit by finding a feedback loop ...
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2answers
206 views

Negative Voltage Converter

I need to generate a negative voltage of approximately -12V from a 12V power supply. I read about ICL7660A that performs supply voltage conversions from positive to negative for an input range of +1....
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0answers
40 views

adjustable voltage controlled current source with negative values

I have a MEMS mirror which can tilt based on the input current. The current can vary between -15mA to +15mA in order to change the angle of the mirror from -15 to +15 degree. Now, I need to have an ...
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3answers
414 views

Supply current of negative rail

I'm using an LTC1983ES6-5 to provide a negative rail for both a MAX4311 and a MAX4395. LTC1983 provides up to 100 mA, but I cannot find in the other datasheets how much current is required for the ...
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0answers
70 views

Why is my signal stronger in the positive than in the negative when i use 2n3819?

simulate this circuit – Schematic created using CircuitLab In the above circuit I have created a JFET amplifier for small signal purposes. When I run tests on the circuit, i get this weird ...
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4answers
100 views

24V DC to +5V and -5V

I need to convert 24V DC to +5V and -5V to power two op-amps (opa2134) and one ATtiny85 with minimal heat generated from the circuit. What voltage regulator would you recommend ? //Digis
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3answers
597 views

ICL7660 - Cannot provide stable negative voltage for audio amplifier

I built this audio amplifier mainly with UA741, ICL7660 etc. The VCC is 5 volt from USB. But I found that the -VCC is quite unstable and this caused noise from speaker, which can hear even when music ...
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3answers
175 views

Current sensing on negative 1.1kV DC rail

I searching for a way to do high side current sensing on a -1100V DC rail. My HV is generated from the hamamatsu C9619 High voltage power supply module and it powers the hamamatsu R647P ...
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3answers
861 views

Is there truely such a thing as a negative DC voltage (with reference to earth ground)?

I understand the concept of a negative voltage. Ground is a reference point and it's easy to get a negative voltage if your ground reference is above earth ground. Does a differential power supply ...
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3answers
332 views

Do an Op-amps supply pins need to have the exact same nominal voltage?

By power supply unit should ideally output +12 and -12V, however the readings are closer to 12.2V and -11.8V. Is this likely to cause a problem, even though I only need an output range of 10V to -10V?...
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2answers
636 views

Negative Voltage Reference for Bipolar ADC

I am considering using ADS1258 - a bipolar ADC. It needs an external reference across REFP(+) and REFN(-). How do I generate precise -2.5V assuming I have +12V and -12V analog voltage rails? I can ...
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2answers
124 views

Polarity question

In a -48 volt DC power plant system how do you determine the polarity of 0v? trying to resolve an issue and not sure how to correctly identify
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3answers
2k views

Generating a Negative Voltage

In general, there are many ways for DC-DC conversion: SMPS, charge pump, linear regulators, zenner diodes, even resistive dividers. But lets say I want to create 2 voltage rails, +Vcc and -Vcc. I can ...
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2answers
225 views

How to obtain negative and positive voltage (±16V) for LM324N

I'm working with the LM324N op-amp. My project requires dual supply, ±16V. How can I produce negative and positive supply from a single supply source? Some project have been using ICL7760 to obtain -...
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4answers
2k views

Are there any single supply OP amps with negative supply voltage?

I learned that basically the only difference between a "single supply" OP amp and a dual supply one is that the former can drive much closer to the negative supply rail. Furthermore if I understand ...
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1answer
240 views

Use Raspberry Pi to power a low noise inverting amplifier with negative voltage input

I am looking to use a Raspberry Pi to power and read the current from a current-to-voltage converter. I am currently using two batteries to power the operational amplifier, as shown in the schematic ...
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3answers
145 views

LM2664 noise in the OPAMPS output signal. How to remove

I have 4 opamps powered from the LM2664. Two of them (1MHZ 1.6V R-R) are preparing the offset voltage for the pair of the OPA4141 which actually provide the signal for the ADC It works as expected ...