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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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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 ...
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?
28
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7answers
6k views

What's the purpose of these two diodes in this circuit?

What's to point of using these two diodes? Can't you just replace them with a resistor?
22
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2answers
3k views

Why do we need a voltage divider when we get the same voltage at the output as the input?

I am using a voltage divider circuit of 100 Ω and 10 kΩ resistors, and using their output for the (IRF740) transistor's input. I'm trying to figure out why do the resistors have those specific values....
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 ...
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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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 ...
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 ...
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=...
12
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3answers
1k views

Why should we need DAC ICs?

Please look at the schematic below. This is a very simple resistive adder that works fine with any standard ! (TTL,CMOS,...) or any arbitrary voltage that is fed into it. On the other hand as there is ...
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 ...
10
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1answer
2k views

The voltage drops measured across very high value resistors do not add up - why is that? [duplicate]

I have a very simple series circuit which I originally built hoping to measure voltage from an Arduino, but while calibrating realized an irregularity, so stripped it down to its basic parts. ...
10
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5answers
1k views

How can I check that the voltage output from this voltage divider is 2.25V?

I was learning about voltage dividers from here, and I decided to try a test circuit with my Radioshack learning lab. With an input voltage of 4.5V and two 1000Ω resistors, I expected the voltage ...
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 ...
9
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5answers
2k views

Does this circuit problem have a solution without an Op-Amp?

I was going through the definition of a voltage follower in this site http://www.learningaboutelectronics.com/Articles/Voltage-follower And a basic problem was presented, and an op-amp voltage ...
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 ...
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 ...
8
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4answers
6k views

Low power design - switch out voltage divider using transistor?

I have a very simple voltage divider circuit for measuring the resistance of a platinum 100 Ohm resistor. I want to be able to switch out the voltage divider circuit from the power supply in order to ...
8
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2answers
893 views

dual of voltage doubler

Voltage doublers, like those close to be one stage of Cockroft-walton multipliers, are well known. They allow to double the voltage of an AC input and can be useful at the output of a transformer for ...
8
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4answers
2k views

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 ...
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 ...
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 ...
7
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5answers
6k views

Are these 2 resistors in parallel?

So I had a circuit to analyse and I needed to find the equivalent resistor and then I arrived to a confusion. Are R1 and R3 in parallel? Here is the circuit. simulate this circuit – Schematic ...
7
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2answers
7k views

Is it possible to step down 240 AC to 5 DC without transformer?

Microcontroller which is controlling mains voltage circuit requires 5 volts to operate. Is it realistic to use diode bridge followed by capacitor to straighten the ac wave and then use voltage divider ...
7
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4answers
13k views

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 ...
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 ...
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 ...
7
votes
1answer
558 views

Down-converting voltage

I'm trying to reduce the voltage of a power supply for a certain load without affecting the current the load draws. Since the op-amps I could find were not able to provide sufficient current, I added ...
7
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2answers
299 views

Setting a part's VCC slightly lower than board's supply voltage

I'm interested in using the undervoltage detection feature (in addition to the primary function) of this chip. This IC draws 6 uA (microamps), and accepts any VCC between 1.6V and 5.5V. The ...
7
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4answers
1k views

Using a digital potentiometer in a voltage divider

I'm using an MCP3008 ADC and an MCP4131-103 (10k) digital potentiometer to try and create a sort of "adjustable voltage divider." For the project, the resistance I'm measuring will vary, and I hoped ...
7
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2answers
377 views

How Do I Limit My Motor Current While Maintaining Voltage Drop Across It?

I am trying to build my knowledge of working with dc motors by using an IRF510 MOSFET to switch a motor on and off. Please refer to the schematic below to see how I hooked everything up. \$S_1\$ = ...
6
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4answers
3k views

Measuring AC voltage without a transformer using a microcontroller

As I have no practice with AC voltages, I'm asking if the following circuit is reliable for measuring AC voltages about 110Vca and 220Vca 50Hz/60Hz. I have already made it with a small transformer. ...
6
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5answers
4k views

Upper limit for resistance values in voltage divider? [duplicate]

I am measuring the voltage of a 24 V battery using the ADC from Arduino Uno. I use a voltage divider to bring the voltage below 5V (the maximum the ADC can accept). I noticed that as long as the ...
6
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1answer
3k views

Voltage divider with diode

I'm having trouble analysing this circuit and was hoping someone could help me. The circuit in question is below. I want to find the voltage drop and current across each of the parts. So far I've ...
6
votes
2answers
768 views

ADC reading 96V DC

I have a 96volt DC line, and I am trying to get it down to 3.3volts to put into an opamp, and then to put into an ADC so that I can read the voltage on the line. The 96volt line will be prone to ...
6
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4answers
8k views

Is using Zener diode with a voltage divider sensible?

I need to convert a floating 12 V voltage to more or less stable 3.3V. So I bought the appropriate Zener diode. Now, since there's such a difference in voltage, I want to make Zener's life simpler and ...
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
votes
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? ...
6
votes
4answers
3k views

Set up an array of pressure sensors

I am working with a flexiforce pressure sensor 25 lb. I have to run 6 of them in parallel and I'm using an Arduino Uno. I'm not an electrical engineer (read: I'm a computer science major) and this is ...
6
votes
2answers
150 views

What are the critical characteristics of an op-amp for buffering reference voltages?

So, let's say I have a precision voltage reference with the output fed to a voltage divider which is tapped at two places for voltages A and B. I've made sure to use precision resistors (or calibrate) ...
5
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3answers
4k views

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 ...
5
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5answers
6k views

If I'm going to use a potentiometer as an adjustable voltage divider, does the tolerance or resistance matter?

Here's what I working with. I'm researching some three terminal potentiometers for use as adjustable voltage dividers. The outer terminals are connected to 0V and 5V respectably, so as I turn the knob,...
5
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5answers
7k views

Using single resistor to receive 5v signal on the 3.3v rated pin

I have been investigating ways to safely receive 5v signal on the input pin that can only support 3.3v input signal. I came across an article that states that it's possible to only use a single 10k ...
5
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2answers
468 views

Voltage rating of low side resistor in voltage divider circuit

I'm building a front end for a data logging project where I need to measure the voltage of a solar PV string. The max voltage I want to design for is 600V. My question is: when choosing resistors R1 ...
5
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3answers
3k views

Choose the resistence with voltage divider sensor

I'm on voltage dividers circuits for reading some sensors that changes their resistance (force sentive resistor). With my tester (with input scale set on 200K ohms) I read 23 if sensor is not touched ...
5
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2answers
603 views

Increase resolution of voltage divider

I have a lead-acid battery on which I am using a voltage divider to measure the remaining charge. Its my understanding that an example battery could discharge from 100-0% over say 10.5V - 12V. ...
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 ...
5
votes
4answers
9k views

When use Voltage divider in circuit analysis

I am trying to find the voltage in R2 with voltage divider, this is the schematic: simulate this circuit – Schematic created using CircuitLab but I can't, and I don't know how to apply the ...
5
votes
2answers
537 views

Voltage Dividers

I've just started design in electronics and am a student of Electrical Engineering. The questions that I have are the following: How many resistors can be used for a voltage divider configuration? Is ...
5
votes
1answer
3k views

Can I use a voltage divider for shifing logic levels?

I'm trying to drive a 3.3V IC from an Arduino which has 5V logic pins, so I need to shift that 5V down. There's no data from the 3.3V device to the Arduino so I don't need to shift back up. Can I use ...