Questions tagged [voltage-divider]

A voltage divider is a circuit that produces an output voltage that is proportional to the input voltage. One typical configuration consists of a pair of resistors in series from the input voltage to ground, with the output voltage taken from the junction of the resistors. As an example two equal valued resistors will give an output voltage 50% of the input.

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21 views

Calculating resistor values for STEF01 overvoltage protection

EDIT : I was making a mistake and there isn't an issue in the data sheet (see answer below). Keeping here for reference to others. The STEF01 is an electronic fuse by ST with features such as soft ...
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Using a voltage divider and an N-channel MOSFET to switch an Arduino input pin from a EL2008 Beckhoff digital output module

I need to switch an Arduino input pin (0-5 V, max current is 40 mA) from an EL2008 Beckhoff digital output module (+24 V HIGH, 0V LOW, max output current of 0.5 A) using the circuit depicted below. I ...
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77 views

Noisy voltage divider question

I have a simple (yet probably stupid question, since my knowledge of analog circtuits is very limited) about voltage dividers. The final goal is to measure AC current for a mains load; to that end, a ...
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121 views

Capacitive voltage divider frequency response and cut-off frequency

I'm working on designing a guitar pedal based on the topology of an old tube amplifier I own. Between the amplification stages I found an inter-stage filter that I cannot understand in the frequency ...
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67 views

How does the voltage at the R4(1) point become 3.78V?

How to calculate the voltage between R4 & R3? I got that due to the two 10k resistors there's a voltage divider happening which causes the point between R1 & R2 to be at 2.5V. But then doesn't ...
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118 views

Circuit Analysis Schematics Conventions in Voltage Divider

I have searched high and low for a diagram similar to this in order to help me understand what little I do know (in an intro college electronics course) but I cannot find anyway to understand this. So ...
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Placement of MOSFETs in switchable voltage divider for voltage measurements

In my battery powered application I am using a switchable voltage divider to not drain the battery. I have seen switchable voltage deviders in two versions: MOSFET at the bottom MOSFET in the middle ...
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TPS61090 LBI Pin-->frequency compensating capacitor for voltage divider?

I was reverse-engineering some PCB to gain knowledge how to apply a TPS61090 Boost Converter (see my schematics attached, sorry for the unusual "arrangement" of the components). Input VBAT ...
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84 views

What is the highest practical value for DC voltage divider

I am using a high side load MOSFET switching circuit as a low current voltage divider. I am trying to minimize the current from the battery V1. How do I determine what is the highest practical value ...
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71 views

Voltage divider circuit load resistance?

For a test on circuits that I just completed, a question asked about a voltage divider circuit (see below.) However, we were told to assume that the load had no resistance and was parallel with the ...
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Measuring battery with low power requirement

I am trying to create a low power device, which would work off a LIR2450 or similar coin cell battery. athe device has long periods of sleep with short periods when it performs operation (e.g. reading ...
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Voltage Divider returns incorrect voltage reading

I have created a simple voltage divider circuit as shown below: Using the simulator, I can see that the voltage measures in at 0.838935V, which is expected. However, when constructing this circuit in ...
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How to modifiy DC2259A evaluation board to access Vref2 on LTC6811-1 IC? For the purpose of powering external thermistors

I am using a DC2259A Evaluation Board, to monitor battery cell voltages and am hoping to drive external thermistor circuits for the purpose of measuring battery cell temperatures from Vref2 on the ...
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107 views

I have a 5 volt converter but I also need 3.3 volts, what should I do?

Goal is to get 5V and 3.3 V output by the use of a buck/boost converter. Important is to use a converter instead of an LDO for heat reasons. I want to draw minimum above 0.8A, preferably 1-1.2A at the ...
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How to improve the accuracy of measured ADC voltage in a circuit connected to Vcc

The question is based on the following setup. As depicted there is an IC to measure the real value of the 3.3V supply voltage accurately. The measured value of the 3.3V source is transferred via SPI ...
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61 views

Switching between three output voltage settings on a switching regulator

I am currently in the process of designing a load control circuit based on a switching voltage regulator. The assumption is that the regulator would provide three different voltage settings based on ...
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76 views

How to make sure that my compensated attenuator would work for certain pulse widths?

I have an input (one-shot) pulse that has to be attenuated by 1/2 (half). The input pulse would be of variable width in between 1us and 100ms and would have a variable amplitude: one voltage level ...
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226 views

How to properly voltage divide an AC/differential signals

What is the proper resistor configuration for voltage dividing an AC or differential source? For simplicity sake assume i would want to reduce a 5v pk-pk perfect sine wave to half 2.5v pk-pk @ 5kHz. ...
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Voltage and Current Stability in a Voltage Divider

simulate this circuit – Schematic created using CircuitLab The voltage divider is used in many circuits such as biasing the base of a transistor, etc. Why is the voltage in the circuit on the ...
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54 views

How are equations (transfer functions) and the uncertainties for sensors found?

Does anyone have a good: book / link / resource which describes from the ground up how to find an equation / transfer function and the accompanying uncertainties for sensors? I am looking for ...
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How to divide 24VAC to 24VDC for use with GPIO

I'm working on a project to gather metrics from my HVAC. I need to detect the presence or absence of 24vAC on two different wires (Y/yellow/cooler, W/white/heater) relative to common - either of which ...
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LTSPICE MOSFET based Voltage Divider SImulation and Real Circuit Results Do Not Match

I am trying to build a very low current voltage divider. I picked high load design using NMOS and PMOS in LTSPICE. In LTSPICE current in R4 is almost zero (nA) when Vin is zero, but in a real circuit ...
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100 views

Understanding L-Pad attenuator

I'm not understanding the concept of L-Pad attenuator other than seeing it as another ordinary voltage divider to attenuate a voltage. Electronics-Tutorials: L-pad Attenuator gives the following ...
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85 views

How to calculate measurement error in a voltage divider?

I'm trying to calculate the measurement uncertainty of the voltage represented by the ADC in +/- V or % of a voltage measured across R2 of a voltage divider. What would be the general way to tackle ...
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38 views

MicroUSB to MCU interface with logical level conversion

I'm trying to interface a micro USB port to a microcontroller but I'm not sure about something. The micro USB port will be connected to a computer with a simple USB cable and that will give me a 5V ...
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What is going on with this piece of equipment?

I am working to automate a machine to come back on after a power flicker. There are three things it needs to do when it starts up: power up, restart function A, and restart function B. Power up ...
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134 views

Filter w/ seemingly higher output voltage than input?

I'm working on a simple LC filter as part of an AM radio project. I was intending to use a ferrite antenna (modeled roughly by the voltage source in series w/ inductor which is then connected to a ...
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146 views

Using a voltage divider versus step-down voltage regulator for i2c pull-up

I have a device (NXQ1TXH5) that I want to run at 5V. I am also interfacing this device with a Raspberry Pi4 for i2c communication. As the title says, I want to pull up SDA/SCL to 3V3, as required by ...
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Is MOSFET Drain Source resistance always affected by Drain Source Current? Is there an IC which is not?

Im trying to measure the voltage of a variable resistor in a voltage divider setup, where the current for the voltage divider is sourced and sunk through a pair of MOSFETS. I assumed that Rdson (drain ...
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My game controller's charging port broke. Now I'm trying to make it run on replaceable batteries, but I'm having some problems

The controller needs 3.7 volts and 250 mAh. I have Kirkland Signature AA batteries. Each are 1.5 volts. Not sure the mAh or whatever that is. How could I raise the voltage from 3 (2 AA batteries) to 3....
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62 views

Voltage divider in combination with pull-down resistor

I am working on a project using the Attiny13 and a simple push button. Since I power the whole circuit with a 3.7V 18650 battery, I have to use a voltage divider to make it safe for the Attiny ...
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Using a diode-connected MOSFETs as a voltage divider

I have read that it is possible to use a diode-connected MOSFET as a small-signal resistor with a resistance of 1/gm (ignoring channel length modulation.) Also, the equation for gm is as follows: ...
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Why is my LM386 reducing voltage and not amplifying it?

LM386 datasheet. I'm working with an 8-bit, R2R-ladder DAC that is connected to the LM386 that is then connected to an 8ohm/3W speaker. The output of the DAC is connected to pin 3 of the amplifier, ...
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134 views

Faulty circuit or faulty opamp?

I want to control voltage on the motor (R1) by microcontroller output (Vin). The problem is that maximum output of the microcontroller is only 2V, while I want voltages on motor up to 12 V. So I ...
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123 views

Voltage Divider to Power LED

I want to construct a voltage divider according to this schematic. I want to set the R1, R2, and R3 voltages to power a LED with a forward voltage of 3,5V and a forward current of 25mA. How should I ...
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Understanding battery voltage detection circuit

I am looking for some battery voltage monitoring circuit and came across this one (I don't have reference now, will add once I get it.) It uses complementary MOSFET pair DMC2400UV to enable the ...
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Voltage Drop/Sag - Current Limited Source

I'm tinkering with the idea of adding a display for gear position on my motorcycle. It already has a gear position sensor that connects a different resistor in series to ground, depending on the gear ...
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546 views

Voltage shift via op amp circuit

I can't figure out a valid circuit for the following conditions: I have an input signal varying from 0 V to 3 V. My ADC's voltage reference is 2.048 V. I only care about the input voltage starting ...
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94 views

Potentiometer partial range usage

I have a 100k ohms potentiometer. My problem is that I have a control stick that goes from left to right representing a very small angle - corresponding to 618 ohms of the potentiometer's range. So ...
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120 views

Voltage drop through a resistor compared to a Zener diode

A variant of this question has been asked a few times, but not received a response. Usually, we get an analogy with water pressure, or gravity, or a version of Ohm's law; not the actual cause-effect ...
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86 views

How to find input impedance for this op amp?

The simulation gives an output voltage of 1.427V and Av of 10. Based on the equation Av= -R2/Ri, Ri should be 7kΩ. However, when I calculate the total impedance using R3+(R1//R4), the impedance is ...
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Why does my voltage (reduced with a voltage divider) drop to zero when connected to a 6V DC motor?

I have the following setup with a voltage divider that steps-down a voltage from 7V to around 6V, so I can plug it into a DC motor. simulate this circuit – Schematic created using CircuitLab ...
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43 views

HVDC measurement in Arduino Uno

I have made a voltage divider with two trim pots set at 900k and 14k with a source voltage of 300V DC. I am supposed to get 4.5V at the center, which I do get and checked by a standard multimeter. Now ...
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56 views

Multiple isolated DC-DC converters in series - ground reference question

I have a question concerning multiple isolated DC-DC converters in series and ground references. I need to measure 48 volts from the input of the first DC-DC converter via a voltage divider, and also ...
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Using many resistors to scale down AC voltage

I've heard it's common practice to use many resistors in series within a voltage divider to scale down an AC voltage for both power dissipation and capacitance considerations (using 10, 100MOhm ...
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Do I need a 48V switch for a voltage divider circuit?

I need to use a rocker switch to turn on a MOSFET. I wanted to use a MOSFET to control when the current flows because I don't want to use a large switch to handle a large amount of current. This is a ...
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79 views

Using voltage divider with appropriate resistor calculations to give +/-1V signal a 1.65V level shift

simulate this circuit – Schematic created using CircuitLab I am trying to use this circuit to level shift V2 which is +/-1v to 0.65 to 2.65V, pretty much adding a 1.65v offset, and I have V1 a 3....
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62 views

Passive Attenuator + Level shift simulation slightly off from hand calculations not sure where mistake is

I am trying to take a +/- 3.5V signal and shift it into the 0.65V to 2.65V range for input into an ADC with common mode of 1.65V. I have calculated the attached circuit by hand but when I simulate it ...
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49 views

Passive Attenuator + Voltage divider to level shift input signal without violating KCL

I have a 7vpp voltage input signal centered at 0V, so +/-3.5V. I wish to turn this into a 2Vpp signal centered at 1.65V, so 0.65V to 2.65V. To start with I have a passive attenuator to give an ...
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239 views

Why is my op amp railing?

So I have a LM358 Dual opamp. I only care about the first op amp, the second I just have set to put out 12V to keep it from floating. The the first is reading in feedback from a 1k potentiometer from ...

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