# 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 that is 50% of the input voltage.

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### When would I use a voltage regulator vs a voltage divider?

When would you use a voltage regulator vs a resistor voltage divider? Are there any uses for which a resistor divider is particularly bad?
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### How to choose value of resistor in voltage divider?

I understand that the output voltage is determined by the ratio between the two resistor values, and that if the both resistors are same then output voltage will be exactly same for all; but what's ...
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### Measure Lithium ion battery voltage (thus remaining capacity)

What I am working with: I am running my self-made Arduino board (in the sense that I use the Arduino bootloader and code editor) at 3.3V, and powered from a Lithium ion battery, which is USB-charged ...
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### Low current battery monitoring

I want to run a micro-controller from a 1S lipo through a 3V linear regulator. I need to measure the battery voltage however. The problem with using a voltage divider is that it would drain the ...
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### Is it safe to use a voltage divider for Arduino and DC motor controller?

I have ordered a Dual H-Bridge 12A continuous (30A peak) Polulu motor driver shield for my upcoming (first time ever, a 1.2m long tank made of wood) robot project. I was thinking about how to supply ...
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### Combined ADC scaling and offset with variable input voltage ranges

I am trying to create a circuit which will allow me to scale and offset a voltage (be it AC or DC) to within the range of the Arduino ADC. The voltage could be anything between + and - 250V, but I ...
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### Sensing AC high voltage to microcontroller

I'd like to sense if I have AC 220V 50HZ available, and convert it to some logical level. I made such circuit, will it work? I use C1 as a resistor. Any recommendations what can be improved? ...
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### 3V power rail from 5V

I've mistakenly ordered some 3V PIC18 L F14K22 instead of the 5V 18F14K22. 3V output is fine for the designed circuit but I need to make a 3V power rail from the available 5V rail. Since only a ...
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### Choosing Voltage Divider Resistor For LDR

I have a 2Mohm dark resistance LDR and i'm wondering what would be the best choice for the fixed resistor. If I made it too large then it would be very insensitive and if I made it too small then it ...
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### Why Did My NPN/PNP Voltage Regulator Experiment Explode?

I have been looking at ways to derive low voltage rails from a higher voltage and current supply, which in practical terms is about 53-0-53V from a linear power supply (toroidal, bridge rectifier and ...
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### Basic voltage divider issue in my amateur circuit XBee

Once again I need your help in my project. I have a 4,5v powered circuit. I put a voltage divider with 2 resistors in series to reduce my initial voltage of 4.5 V to 3.4 V (to feed an XBee module). ...
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### Which is the correct voltage reference for a single supply instrumentation amplifier?

I'm working on using the TI INA333 in a single 3v supply configuration. I need to create a "mid supply" (half V+) for the REF pin. I have thought of 3 ways to do this: Voltage divider with ...
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### MOSFET as a voltage controlled resistor

This question might be too localized, but I try. Is it possible to replace a variable resistor by a MOSFET, under conditions shown in the following schematic? If yes, can someone propose a MOSFET ...
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### Circuit for a coarse and fine setting potentiometer?

I've tried to find a circuit for a coarse and fine adjustment (two potentiometers) voltage divider, but I don't understand it and/or they don't have a linear response. Problem: I want to have an ...
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### Is voltage divider applicable on circuits where there is no ground?

For the circuit below, if the bottom terminal is -Vin and not grounded, is applying voltage divider possible at all? If this is the case, what would the equation be? I never heard of a voltage ...
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### PIC - How to skirt around low maximum ADC input impedance?

Reading a 9V battery on a PIC is nothing new. The most simple and straightforward way is with a voltage divider. I'd like to keep the divider resistances cranked up into the hundreds of kohms so I'm ...
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### Can we explain the differential pair in terms of resistances?

It has always been a big challenge for me to find the most general ideas behind great circuit solutions that can be illustrated by simple electrical concepts... and even by non-electrical analogies ...
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### How to determine resistor value for given voltages

I'm not sure how to solve the following problem (I'm not asking or complete solutions, just for a hint on where to start!). I'm asked to find the values for R1, R2 and R3. I know it is a voltage ...
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### Low power battery voltage monitor

I would like to measure the battery usage of my ESP32 device. As my device runs in deep sleep mode 99% of the time, it's important that the battery monitoring circuit does not add too much to the ...
10k views

### Negative Voltage Level Shifting to an ADC

I am currently building a project that uses an AD595 analog devices chip to linearize the output of the Thermocouple sensor to 10mv/deg C. This output is to be connected to the ADC input of a Zigbee ...
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1 vote
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### How to measure line voltage (220V) with an arduino?

I'm a Electrical Engineering student and I want to sense and sample the voltage signal coming from a wall socket (110V - 220V). I came up with the following circuit using a voltage divider with high ...
1 vote
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### Impedance to voltage range

I'm trying to get a voltage in a range from a potentiometer. The potentiometer theorically varies between 22k and 40k (R1 in the shematic) but I'm unsure as I currently don't have it in my hands. I ...
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### Powering Arduino from a voltage divider

I'm making a voltmeter for the college senior project, and the problem is that voltage divider should equally split 17V into two 9V(nominal value of the batteries. As of now, an actual voltage is 8.5V ...
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### Finding Node Voltage

I need to find node voltage at A. This seems like a trivial question, but when I set up the resistive voltage divider equations they are not equal to each other. Am I doing something wrong? My ...
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### How make a dual +-12V supply from a 24V SMPS

I'm trying to power a home-made load cell transmitter using a 24V single SMPS. I need to make +12, 0 and -12 Volts that are capable of 50mA. I wish to power multiple channels of opamps and bridges. I ...
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### Is this clamping voltage divider for a high-impedance input a good, robust design?

I have an AC input as follows: Can range from ±10V to at least ±500V continuously. Runs from roughly 1 Hz to 1 kHz. Needs > 100 kΩ of impedance on it, otherwise its amplitude changes. May ...
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### Which one is better as voltage divider: resistive, capacitive , low pass filter,...?

There are different types of voltage attenuators for AC signals ( a short explanation is here). The most well known is a resistive one. Others like capacitive, inductive or low pass filters are ...
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### Divider and lowpass combined

I am using the following circuit for two purposes: As a voltage divider, to reduce DC sensor output to a range suitable for my ADC. As a lowpass filter, to remove high frequency noise from the signal....
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### How does the electricity "know" the ratio of the resistance in a voltage divider?

I'm having a hard time conceptualizing what/how things are working in a voltage divider setup. I've read a couple other questions/explanations where the answerer has said to "not think about it in ...
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### How can I rearrange the voltage divider formula for R2?

Can I please have a step by step explanation as to how I can rearrange the voltage divider formula to find R2. I dont understand how I end up with R2 = R1 x Vout/Vin - Vout.
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### What is the voltage drop across the 10 ohm resistor?

What is the voltage drop (V1) across the 10 ohm resistor? Can I use voltage division to get V1? Like V1 = (20 V x 10 Ω) / (10 Ω + 4 Ω) But when I use nodal analysis and mesh analysis I get a different ...
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### Measuring Battery Voltage from Microcontroller using ADC

I am currently using a PIC16f1826 to try and measure the voltage of the 3.7v battery that is powering said microcontroller. From my understanding, the ADC can measure from 0v up to the reference ...
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### 5V 4-pin Noctua A4X10 on Raspberry Pi

I want to connect a NOCTUA NF-A4X10 5V PWM 4-pin fan to a Raspberry Pi 3B. The below is the circuit I'm planning to use. (EDIT: Flyback diode (such as a 1N4001) is not needed since Noctua already ...
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### What is the purpose of the three part circuit?

I'm studying for my final on introduction to circuits and came across a question about this circuit: The question is: Identify and describe the three parts of the circuit used for a measurement ...
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### Unstable readings in photoresistor matrix with Arduino, OK with Ohmmeter - what's wrong?

I'm working on a photoresistor array with my arduino, and I'm having a little trouble getting stable readings. I'm driving 7 rows one at a time with Arduino's ...
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### Questions on Operational Amplifiers

What I've learned so far from Navy school is that operational amplifiers are used as a substitute for transistor amplifiers and they contain three main circuits: the differential amplifier, common ...
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### How to reduce 24V to 0- 2.5V through a pot?

I have a 24V DC supply and I need to give a heater a 0-2.5V variable input. I have a very limited understanding on electronics but I've read here about voltage dividers. I used a 10k pot (and the 2 ...
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I am working on putting together an Arduino board that would read signals sent between two modules in a car. The signals are sent as 8V square waves. An example of a message sent this way would be a ...
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### voltage divider -- for detecting higher voltage in ADC

I am working on a BLDC sensorless motor. I need to detect BEMF Zero-cross event. My Motor is working on 24 Volt power. Now I need to detect the back E.M.F. As refered in this application note. My ...
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### Multiple Staged BJT Amplifier

Here is shown the design of simple multi-staged amplifier. simulate this circuit – Schematic created using CircuitLab I tried to put together all three NPN transistor configurations and this ...
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Say you were wanting to measure a signal with a higher voltage than the ADC could handle. Is there some best practice or commonly used circuitry that goes beyond a simple voltage divider to protect ...
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### Multiple voltage dividers

So I have this circuit. I've been trying to figure out Vout. I couldn't find a specific formula for this situation. Can anyone help me figure out the formula? Thank you.
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I'm new to electronics. So basically I already understand Ohm's law and the math behind why this is the case. What I don't get is the idea behind it. Shouldn't the greater the load resistance be, the ...
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### Calculate resistors value in voltage divider

I have the following voltage divider circuit with a potentiomenter, and I need to find the value of the resistors. simulate this circuit – Schematic created using CircuitLab How can I find the ...
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### Voltage Divider vs. Resistor in Series

What is the difference between having a voltage divider vs just using a resistor in series. So for example, I have an input voltage with 12V, and two resistors in a voltage divider, R1=10k, and R2=...
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### LTspice fails at a simple two-resistor voltage divider. How can I fix it?

During some simulations, I noticed some oddities and narrowed it down to the following problem: This is is simple voltage divider using two resistors. The four traces show: supply voltage current ...
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### Output impedance of voltage divider?

When connecting a 10S LiPo (42V) to my ADC via a voltage divider, I began wondering how to calculate the output impedance of the divider. simulate this circuit – Schematic created using ...
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### Does the value of a resistor matter when doing voltage division to cut it into a half?

I have a 7.4V (8.4V when fully charged) battery that is connected to an Arduino and I need to monitor the battery. To do so, I need to plug the battery into an analog pin. However, that pin only ...
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### Zero or low-current voltage divider for switch identification

Is it possible to design a voltage divider circuit with switches that uses zero current, or very low current? Would it work to use a transistor to connect/disconnect the end of resistor string from ...
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