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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29
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4answers
32k views

When would I use a voltage regulator vs 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?
13
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3answers
16k views

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 ...
42
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5answers
78k views

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 ...
13
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3answers
15k views

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 ...
6
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2answers
7k views

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 ...
6
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3answers
17k views

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? ...
3
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2answers
4k views

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 ...
2
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2answers
1k views

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 ...
2
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1answer
808 views

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). ...
2
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2answers
1k views

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 ...
7
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3answers
5k views

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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4answers
4k views

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 ...
0
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4answers
827 views

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 ...
12
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4answers
2k views

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 ...
18
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2answers
56k views

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 ...
8
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6answers
3k views

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 ...
2
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3answers
4k views

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....
8
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8answers
3k views

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 ...
1
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2answers
420 views

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 ...
10
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3answers
12k views

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 ...
3
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1answer
14k views

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.
2
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3answers
11k views

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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3answers
1k views

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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2answers
8k 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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2answers
498 views

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 ...
0
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2answers
660 views

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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3answers
1k views

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 ...
16
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7answers
5k views

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 ...
13
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5answers
9k views

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=...
7
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6answers
2k views

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 ...
4
votes
1answer
5k views

How does the input circuit on this oscilloscope manage to accept such a large range of voltages?

I recently bought this ($45!) oscilloscope: http://www.gabotronics.com/development-boards/xmega-xprotolab.htm. Looking at its schematic, I see the circuitry for one of the two analog input channels: ...
8
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1answer
4k views

op-amps: where to split the rail?

I have been experimenting with op-amp audio amplifiers powered from a 9V battery. I am just wondering how I should go about splitting the voltage from the battery, as I have found 2 ways of doing this ...
4
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2answers
11k views

What is the voltage divider rule?

Can anyone explain what the voltage divider rule is? How has the author of this book used it for analyzing the Voltage Divider Bias circuit for transistors? And can anyone explain how the two ...
4
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2answers
3k views

How to measure AC voltage without a voltage divider using microcontroller

I have to measure AC voltage of the mains supply 180-220 VAC through a microcontroller. I have been wondering how to measure it without using a voltage divider. Since the resistance may wear out with ...
3
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3answers
8k views

Arduino Uno reading analog 24v DC signal

Disclaimer: Please be gentle - I'm a newbie with electronics. Overview I have a proprietary 24v DC analog sensor signal that I'm trying to interface with using a Arduino based microcontroller. The ...
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4answers
10k views

How to connect Raspberry Pi to House Alarm Serial Bus (DSC Keybus)

I have a DSC 1864 House Alarm and I want to connect up my Raspberry Pi's GPIO to the Keybus (a serial data communication protocol used by the alarm). I would say my knowledge of electronics is novice ...
1
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2answers
476 views

Output impedance of Op Amp with Voltage Divider?

I'm trying to figure out the output impedance of this op Amp circuit and I keep getting infinity. I'm not sure if the steps I'm doing are wrong. The reason I ignore everything besides the voltage ...
8
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2answers
6k views

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 ...
5
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4answers
1k views

Do voltage dividers waste battery?

I am attempting to make a battery powered alarm clock with an Arduino, and I would appreciate some help on the circuitry part. I am very inexperienced with electrical engineering. I am using a ...
4
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2answers
299 views

Ideal Op-amp Question with complicated feedback resistance

The question has been asked before here: Help with ideal op-amp problem I don't understand why we simply can't reduce \$R_2\$, \$R_3\$ and \$R_4\$ into one single feedback resistance: $$R_f=R_4+R_2 \...
3
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3answers
330 views

Oscillation in Voltage Rectifier / Scaling Circuit

I am working on creating a circuit that will scale +/- 12v input to a unipolar 3.3v centered around 1.65v, in order to scale the kind of CV used in modular synthesis systems to work with the ADCs on ...
2
votes
4answers
5k views

converting 3.3v to 1.2v

I have a electrical problem that I hope to get some help with. Let me first start of by saying that I'm quite a noob in this field (I'm a IT guy), but I hope to learn something. The problem I have is ...
2
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3answers
14k views

Is voltage divider output affected by load resistance?

Very basic question. Assume a voltage divider where both divider resistors are equal value, i.e. 100K. If 48v is the applied voltage, it's easy to see that we'll measure 24v across the "load resistor"....
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1answer
2k views

Use BBB analog inputs with 0..5V or 0..10V

I plan to use the BeagleBone Black analog inputs for sampling of analog data. But there are some major problems for this: BBB allows a maximum of 1.8 V analog input voltage while I have 5 V or 10 V ...
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2answers
6k views

How are the resistor values R1 and R2 calculated for a transistor amplifier that has a voltage divider bias

Good day friends I am trying to analyse the working of transistor amplifiers with a prime goal of designing a good audio amplifier that does not produce much distortion in the output. I am ...
1
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4answers
2k views

Why is it necessary to use a voltage divider to bias the base voltage in a common emitter amplifier?

I have seen different common emitter amplifier designs with either a voltage divider or a simple resistor between the battery and the base. What would make us choose a voltage divider over a simple ...
1
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1answer
316 views

Why is the voltage across collector and emitter pushing itself to 0.7 volts?

I designed a single stage transistor amplifier as shown in this schematic: I constructed this on a breadboard and applied the DC bias voltage to check the biasing conditions. Prior to this, I made ...
0
votes
4answers
168 views

Arduino: read different voltage values in a range from -12 to +12V

I would like to trigger different functions in Arduino related to the following voltage values: -12V, 0V, 6V, 9V, 12V (the range is from -12V to +12V). According to the value of the voltage read (-...
0
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1answer
120 views

How to find the equivalent resistances for each filter so that the cutoff frequencies can be found?

Hello i am having trouble for this following circuit. (Top circuit in diagram1) The problem i am having is finding how to calculate the cutoff frequencies for the highpass filter and lowpass filter. ...
0
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3answers
420 views

Simple Capacitor Charging Question

Right, I have a very simple circuit that I aim to use as a delay circuit, everything was going fine until I started to over think it all and now I have totally confused myself and it is slightly ...