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# Questions tagged [negative-voltage]

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### DC-DC converter to make variable output +/-70V from 5V input

This is a SEPIC DC-DC architecture from Texas Instruments to make a variable output from +/-5V to +/-70V. Iwould like to understand the principle of how the negative voltage is being made from the ...
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0 votes
1 answer
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### Delay in discharging of the capacitor for sequencing purpose

Our aim is to sequence 2 different power supplies i.e. 5 V and -48 V. On sequence is first "5 V is generated" and then "-48 V is generated" with 120 ms delay. Off sequence is first ...
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### Multiplexing Solar Cells with a Common Positive

I am trying to switch between 6 pixels of a Perovskite Solar cell that exist on a single slide. I hope this would allow me to measure their voltage and current with one four-wire measurement ...
1 vote
3 answers
78 views

### More current draw from a power supply based on a voltage divider

I've built a circuit that needs a power supply that can provide -12V, 5V and 12V. I've built the circuit below as a proof of concept, being aware that I might need to build something that allows for ...
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### Generate 200MHz Phase-Shifted Voltage Sine Waves

I'm looking into a way to construct a circuit that can generate ~200MHz negative voltage sine waves (8 channels), where there is 11 degrees of phase offset between the channels (0 deg, 11 deg, 22 deg, ...
1 vote
1 answer
34 views

### How do the switches and level translator work in the LMC7660 Switched Capacitor Voltage Converter [closed]

This is the block diagram of Texas Instruments LMC7660: Here 4 switches are used S1 to S4. The diagram shows source connection of only two transistors S1 and S2, and leaves out the S3 and S4 switch. ...
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34 views

### STM32L432KC used for negative voltage?

My TIA circuit's opamp needs a negative supply in order to get a output with a 2V dc bias and ac signal that the stm adc can sample. This is needed since the opamp needs a ~3V difference between input ...
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1 answer
64 views

### TIA needs negative voltage supply

My TIA (figure 1) needs due to its op amp at least a negative voltage supply. There is needed a 3V difference (datasheet op amp). But how can I create this negative supply, I have a 12V dc power ...
5 votes
4 answers
469 views

### Ground in differential opamp situation

I have a setup like such in the provided schematic. The idea is that I do have a -2.5 to 2.5V signal which I'd like to convert to a signal between 0 and 5V. How should I connect my opamp? Should the ...
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### Protecting negative power rail

I don't trust my power supply and want to protect my circuitry from over(under)-voltage, but cannot find a clear path of going forward with negative power rail. LDO which I use (LT3094) is rated for ...
1 vote
0 answers
72 views

### Is it possible to use an Efuse for protection with negative voltage?

Following to this question, is it possible to use an efuse with a negative voltage power, to eliminate the need of the required big heatsinks?
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1 vote
2 answers
100 views

### Isolated negative Vdg on MOSFET

This is probably crazy, but: What would happen if I apply a negative voltage between the drain and the gate of a MOSFET (or positive from gate to drain), assuming that this voltage comes from an ...
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### High negative voltage cut-off for op-amp from dual-rail power supply

In the picture I have a circuit that prevents reverse polarity and cuts the voltage with respect to the Zener diode (15 V) as a voltage reference for positive voltage output. How do I apply the same ...
1 vote
2 answers
159 views

### Voltage comparator approach

I am building a self biased tube amp. It has an adjustable negative bias of about -32 to -67 Vdc for various tubes. The power supply side has some bult in safeties to make sure there's always a ...
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4 votes
3 answers
980 views

### How does this negative voltage rail work?

Rod Elliot has a dual bench power supply project on his web site (project 223, see schematic below). I'm trying to understand his method for adding a low voltage negative rail without using an ...
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1 answer
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### Which MCU ADC configuration works best for bipolar input measurement [closed]

The jumper pads can be set to configure the input pins connected to an MCU. Which configuration would work best to enable reading negative voltages?
1 vote
1 answer
105 views

### Is negative voltage going to cause trouble?

I'm trying to design a circuit that will allow me to set and reset an SR-latch with a single input. My idea is that when the input is driven high, the latch immediately resets, and if it persists for ...
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2 votes
2 answers
633 views

### µA723 output Zener diode: why is it as high as 6.2 V?

The µA723 voltage regulator has a 6.2 V Zener diode on its output. I am trying to understand why the Zener voltage is as high as 6.2 V. (LM723 or LM723C are more or less equivalent parts, raising ...
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2 votes
6 answers
2k views

### How come negative power supply has negative voltage only

So I have seen power supplies that produce e.g. -48V DC (used e.g. in telecom but probably not only). For sure, that power supply is floating and in no way is negative terminal connected to earth. So, ...
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0 answers
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### LT1054 wrong output

I'm using a LT1054 to generate a negative voltage to power my OpAmp's. I used the circuit described in figure TA03 of the datasheet. My Vin is 15 V and my R1 and R2 are 20k and 220k respectively. With ...
2 votes
4 answers
484 views

### Summing Amplifier Supply Voltage

Consider the case that I have a standard inverting summing amplifier with two inputs: 0.5V DC and 1V DC. Therefore, the output of the amplifier should be -1.5V related to GND. However, If I connect ...
1 vote
1 answer
108 views

### How to obtain negative voltage for op-amp?

How to setup negative -10 V for an op-amp to be designed on a PCB? I read that -10 V can be obtained from a power supply by connecting positive to ground and negative of the supply to the node where ...
1 vote
1 answer
275 views

### Using a DCDC buck converter for negative supply

I am still fairly new to DC/DC converters and was wondering how to generate negative output supply with a positive input supply. I don't know what the general requirements and limitations are but here'...
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3 votes
1 answer
2k views

### Op-amp dual supply methods

To power an op-amp with a dual supply (+Vcc and -Vcc) you can use two power supplies connected in series. I would like to find an alternative and less expensive way to do this as (in my project) the ...
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1 vote
1 answer
133 views

### Creating -5V supply from a AC/DC adapter

I want to use a Friwo FOX12-XM 5.9V adapter from RS with a -5V LDO to create a -5V supply which I draw as follows: Would this be fine and is the adapter isolated?
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1 vote
2 answers
265 views

### What is the most used bi-polar output SMPS topology in gate driver isolation?

I have some questions concerning this schematic: What is the topology used here? I am guessing flyback without feedback circuitry. Why is the TPS40211 utilized here? Is it to provide more current? ...
4 votes
3 answers
3k views

### How to generate -5 V from +5 V and GND?

I have an Arduino providing +5 V and GND. I have a component that requires +5 V, common GND, and -5 V connections. Is it possible to generate -5 V? If not, what input voltage do I need? I am driving a ...
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2 votes
2 answers
368 views

### Is it possible to use one voltage source for an op-amp?

This is a typical to op-amp for a non-inverting amplifier. I have tried to google this before I asked this question. Unfortunately, all circuit diagrams seem to require two voltage sources. In real ...
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2 answers
162 views

### ±50 V from two 50 V DC-DC boost converters

I am having trouble building a power supply for my car audio amplifier board. The board needs a ±50 V, 250 W RMS PSU, which is why I bought two switch-mode power supplies, each 50 V, to connect them ...
3 votes
4 answers
2k views

### How can I supply −5 V to an op-amp?

This is the circuit that I intend to implement on a breadboard. I only have an ESP32 microcontroller, so I can supply the +5 V, but I have no idea how to supply the −5 V. If I change Vee to 0 V (GND ...
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0 votes
3 answers
363 views

### 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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0 votes
1 answer
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### 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 ...
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2 votes
1 answer
936 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
160 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
1k views

### 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
394 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'...
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50 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
219 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
67 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 ...
0 votes
1 answer
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### 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
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### Using NMOSFET for driving negative voltage

I want to use NMOSFEts for driving negative voltage. Is it possible to use it?
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1 vote
1 answer
217 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 ...
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0 answers
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### 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
229 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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1 vote
1 answer
353 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
3k 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) ...
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-1 votes
2 answers
60 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
245 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
86 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
3k 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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