Questions tagged [negative-voltage]

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3 answers
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Biasing a low AC voltage for input to an ADS1115 ADC

I have an AC signal from a position sensor that changes between -200 mV and 200 mV, something like 400mV peak-to-peak. I have ordered an ADS1115 breadboard and I use an STM32 microcontroller. I'm not ...
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1 answer
55 views

Use GND as V- in voltage regulator

For a circuit sensor, I need +15 V/GND/-15 V. My supply voltage is a single +5 V rail from a standard switching PSU. I looked at different voltage regulators and found, besides others, the ITA series ...
2 votes
1 answer
46 views

Negative voltage from a positive LDO

I came across this design which generates +1.5V and 1.5V from https://simple-circuit.com/arduino-ac-current-measurement-current-transformer/) My question is: with the same DC/DC isolated transformer, ...
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-1 votes
1 answer
51 views

Using 12V output as ground in 24V power supply to form +/-12V rails

I have a power supply which outputs both +12V and +24V, Here's a photo: Can I use the +12V as ground in my circuit to have a -12V(from 0V)/+12V(from 24V) output? The load on the -12V output will be ~...
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1 vote
1 answer
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Positive and negative voltage level shifter + inverter

I am looking for a level shifter/inverter that not only changes the high-state to another voltage but also generates a negative low-state voltage. The output of Inverter 1 is fixed to (0V … 600 mV), ...
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1 answer
62 views

How to get negative voltage on PWM signal

I'm researching EV charging stations. Looking at the SAE J1772 communication protocol, I see that there is a +12 to -12 volt 1 kHz PWM signal on the control pilot, which indicates the charging station'...
0 votes
0 answers
37 views

Using negative supply rail instead of ground in SMPS IC

I'm working on a solar power inverter I noticed that all PWM ICs using negative 12 rail as a gnd... As an example a PWM IC SG3524 which is used to convert batteries voltage to high dc bus voltage used ...
0 votes
1 answer
73 views

low voltage cutoff for negative voltages

I've been trying to design a simple low voltage cut-off circuit for my dual supply +-9V circuit. The positive side works as intended with the LM431 and a PMOS, but the negative side not so much. The ...
0 votes
1 answer
58 views

Positive and negative voltage readings across a rig simulating bearing contact, supplied with a DC source

I recently ran a few experiments to simulate the effects of shaft voltages on motor bearings through using a simplified experimental rig. The rig simulates bearing contact. I applied a DC source ...
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1 answer
56 views

Powering nixie tube from negative voltage?

I've built a photomultiplier tube supply; it takes +100VDC from a boost converter, which then goes through an inverting (in the sense of postive->negative rather than DC->AC) charge pump to give ...
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0 answers
43 views

Using NMOSFET for driving negative voltage

I want to use NMOSFEts for driving negative voltage. Is it possible to use it?
1 vote
1 answer
101 views

Philips PE1535 bench power supply - reason for design choice?

Just a little question about the Philips power supply PE1535. Link to original manual : http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Philips/PE1535%20-%20PE1545.pdf Why the negative power supply ...
1 vote
0 answers
90 views

How to safely read +-5V with an Arduino

I have a -5V +5V binary signal coming from a CNC controller that I want to read with an Arduino. This is the way I have it setup: The resistors are actually 10K. The left voltage source would be the ...
1 vote
1 answer
87 views

Does the negative voltage regulator emit noise into ground

I am designing an inverting voltage regulator using a LT3758 controller to generate -15 V from a 12 V / 5 V input. This is a non-isolated regulator. My biggest concern implementing the design is if ...
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0 votes
1 answer
108 views

Contrast voltage for display from PWM with negative rail

I want to control the contrast of this display using a well-filtered PWM output. They recommend a potentiometer between Vdd and Vee (negative built-in rail): With my MCU I can generate a filtered PWM ...
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1 vote
4 answers
397 views

If you source a negative voltage from a power supply, should the current be negative also?

I am clear that negative currents are simply currents that flow in the opposite direction. I am unsure as to how to apply this information to the real world. (relating to positive and negative leads) ...
-1 votes
2 answers
54 views

DC to DC converter connection [closed]

I am fairly new to electronics and I started to have some doubts. I am going to use a DC to DC converter R1SE-0505/H2-R (5V to 5V) to have an isolated power supply for the audio components. I have ...
0 votes
1 answer
114 views

Negative voltage value for AD620 amplifier

I am using AD620 to amplify the signal of a pressure sensor, and a negative supply voltage must be added to V- pin. should the negative voltage value be the same as the positive supply voltage? or any ...
0 votes
2 answers
49 views

OP2177 opamp with single supply

Does anyone know if I can use "OP2177" with a single supply without a negative voltage on V- ?
11 votes
5 answers
2k views

Is it OK to create a negative rail just by dividing voltage with resistors?

I want to build some circuits to learn about op-amps, and so I would like to set up a negative rail. Are there any problems in creating a negative rail by using an 18 V bench supply and then simply ...
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1 vote
2 answers
198 views

Improve the response of this circuit

I designed this circuit (shown below) to level shift an input PWM (10 kHz 5% duty) signal (from microcontroller, 0/+3V3) to 0 and -12V. When the input PWM is HIGH (+3V3) the output is at 0V while when ...
0 votes
1 answer
145 views

PWM level shift

I have a 10 kHz PWM (0V (LOW) to 3V3 (HIGH)) which I wish to level shift as following; when PWM is high (3V3) the output should be 0V while when PWM is low (0V) the output should be -12V. Ideally this ...
2 votes
2 answers
2k 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 ...
1 vote
2 answers
127 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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0 votes
1 answer
78 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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1 vote
1 answer
44 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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1 vote
1 answer
121 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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0 votes
1 answer
107 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. ...
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0 votes
1 answer
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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 ...
0 votes
3 answers
943 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 ...
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2 votes
1 answer
459 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 ...
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0 votes
1 answer
56 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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6 votes
5 answers
1k 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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0 answers
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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. ...
0 votes
1 answer
135 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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0 votes
1 answer
135 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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0 votes
2 answers
93 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 ...
0 votes
2 answers
803 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 ...
1 vote
1 answer
115 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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0 votes
1 answer
244 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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3 votes
0 answers
47 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 ...
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0 votes
1 answer
369 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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3 votes
2 answers
1k 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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1 vote
1 answer
159 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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0 votes
1 answer
119 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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1 answer
92 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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2 answers
52 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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0 votes
1 answer
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'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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0 answers
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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 ...
1 vote
1 answer
241 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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