What is Voltage divider: Definition and 91 Discussions

In electronics, a voltage divider (also known as a potential divider) is a passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). Voltage division is the result of distributing the input voltage among the components of the divider. A simple example of a voltage divider is two resistors connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them.
Resistor voltage dividers are commonly used to create reference voltages, or to reduce the magnitude of a voltage so it can be measured, and may also be used as signal attenuators at low frequencies. For direct current and relatively low frequencies, a voltage divider may be sufficiently accurate if made only of resistors; where frequency response over a wide range is required (such as in an oscilloscope probe), a voltage divider may have capacitive elements added to compensate load capacitance. In electric power transmission, a capacitive voltage divider is used for measurement of high voltage.

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  1. I

    Need a voltage divider for a capacitor source voltage

    The end goal is I need to convert a sinusoidal into a square wave using a zero crossing circuit. I have a voltage that ranges from 0 to 400vrms @70kHz from a capacitor that is part of an induction heater tank circuit. My comparator has a peak differential input of +/- 35v so I need to reduce the...
  2. altruan23

    Engineering Op amp circuit -- Did I calculate the output voltage correctly?

    can someone check, if i calculated the output voltage correct? i used virtual ground because V+-input of the op amp is 0 --> V- input is then also 0.
  3. altruan23

    Simple voltage divider -- why does this work?

    Summary:: don't understand how can we use a voltage that has been already dropped. I don't understand the voltage divider. So R1 and R2 are the same. I have 10 V in beginning, then 5V drop across R1 and then i have 5V drop across R2. But how can I use the 5V if they already dropped at R2? If...
  4. P

    Investigating the Effects of a Common Emitter Amplifier

    Summary:: Using a common emitter amplifier to pump up the input voltage, and studying the effects henceforth. Here is a circuit with 0.6V pk-pk input voltage (v_in) for the CE amplifier, 1.17 kHz frequency- For this, without C5 and R9, the AC and DC gain was -10. I was supposed to increase...
  5. K

    Buck converter will power LED's but voltage divider will not....

    Summary: Am seeking help understanding why when I take my battery (50V max 44 nominal; 15aH capacity; 12s5p) and attempt to step down the voltage that sometimes it works and sometimes not... Hi all, New to forum. Chemical engineer seeks help from electrical engineers... Thanks for reading...
  6. J

    Voltage divider rule for CMOS in 0-state and leakage current

    I use the voltage divider rule as output voltage = Voltage across R1 = 5 * ( 0.5 / (0.5 + 20) ) This comes as 0.122 V I'm not sure why they've mentioned I leakage and does 0-state have any impact on answer.
  7. B

    Unknown Instrumentation: Antenna voltage monitor?

    I have this piece of instrumentation that I am trying to model that I am not entirely sure how it functions. I am certain that it is a voltage monitor. It's basically a voltage divider (v_out = .017*v_in) enclosed in a grounded box with two holes on either side for the connections to the...
  8. OldWorldBlues

    Why Use Voltage Dividers Instead of a Single Resistor?

    Hi! I'm working on a project in which a small microcontroller with a max. analog input of 5v takes readings from multiple sensors. I would like to make this input window a bit more versatile, and turned to voltage dividers as a solution. 'Problem is, I'm having a bit of trouble understanding how...
  9. B

    How to find the relative error in the voltage reading

    Homework Statement For a circuit with 3 resistors in series (R1=1.00 kOhms, R2=2.50 kOhms, R3= 4.00 kOhms and Va=12.0 V). A voltmeter was placed across R2 and R3. Calculate the relative error in the voltage reading if the internal resistance of the voltmeter was a) 5000 ohms, b) 50 kOhms, C)...
  10. W

    Proof of Wheatstone bridge equation

    Homework Statement Prove the following equation: ## \Delta U=\frac {R_1R_4}{(R_1+R_4)^2}(\frac {\Delta R_1}{R_1}-\frac {\Delta R_2}{R_2}+\frac{\Delta R_3}{R_3}-\frac{\Delta R_4}{R_4})E## This is used in Wheatstone bridge Homework Equations [/B] U=RI The Attempt at a Solution This has...
  11. M

    Finding output voltage given two resistances and voltages

    Given two sets of load resistances and output voltages: Rload = 108 ohms - Vout = 9.6V Rload = 10 Ohms - Vout = 2.3V Find the source voltage and the output voltage when R1 and R2 are equal. When the resistance is very large, the voltage seems to be around 9.6. My assumption was that then the...
  12. F

    Calculating Voltage in a Simple Divider Circuit

    Homework Statement Not technically a homework question but part of a piece of work I am studying. I need to calculate the voltage at the node in between the 10k and 27k resistors in the following schematic. I'll call it Vo. https://www.physicsforums.com/attachments/213624 Homework Equations...
  13. F

    Do Transistors That Divide Voltage Exist?

    So I know a transistor is built to amplify or multiple an input signal using a base voltage. Are there such transistors that are analog? That is the output voltage is amplified depending on the base voltage? If so, is there analogously a transistor that divides instead of multiplies? That is...
  14. J

    Limiting amps and volts from a battery

    I have a project that involves a small motor, and the battery powering it would blow the motor in an instant without proper use of resistors. The battery I'm using is rated at 9.6 volts and 1600ma. The motor however, is rated at 3 volts and 0.3 Amps. I would like to go just under these ratings...
  15. D

    Transfer function question opamp + voltage divider

    〖 mod note: moved from technical forum, so template is missing 〗 〖 mod note: click on thumbprint image to see legible image 〗 I was wondering if anyone could provide some more insight as to how to find the current through Rc. The first picture TRANSFER1 I can find the current Ic through Rc...
  16. EddNeedsHelp

    Engineering Solving for resistor values in voltage divider circuit

    Homework Statement So I was studying an example and the picture given simply asked to setup a voltage divider for the values without solving for resistance. However... I want to know if I'm missing something or if this can even be solved: I attached the problem below. Homework Equations...
  17. Rx7man

    Voltage divider with offset

    I'm working on an Arduino project to read automotive battery voltage,.. I could use a simple resistor divider circuit, but I'd lose a lot of resolution (you aren't going to see <8V very often).. Could anyone take a look at this and tell me if it's a reasonable method?.. Channel A (Blue) is...
  18. Adeel Ahmad

    Electricity, finding voltage and resistance

    Homework Statement Design a voltage divider circuit to provide an output voltage v0 = 5V from a 12V source. The current taken from the 12V source is to be 100mA. a)Find the values of R1 and R2. b)Now suppose a load resistance of 200 ohms is connected across the output terminals (in parallel...
  19. Borek

    What is the purpose of a capacitor in a voltage divider circuit?

    I need a voltage divider to make it possible to measure voltage on the 3S LiPo battery that delivers around 11 V using a device that measures up to 4 V (approx). I can make one, no problem, just solder two resistors with resistances in the more or less 1:3 ratio (measured output is sent as a...
  20. D

    Voltage divider not working for fan

    I have a 24 volt power supply to power a 12 volt fan. Since I don't want to burn the motor out I used a voltage divider with two 1kΩ resisters to cut the voltage in half. I measured that the voltage on the divider is 12 V, so this is good. However, it won't drive the fan. When I hook the fan...
  21. Planobilly

    Questions about voltage divider circuits

    Say I had a 10VDC supply and I need around 3.3VDC at 30ma. Let's say the 3.3VDC will power a LED. V1= 10VDC R1= 82 ohms R2= 47 ohms V2= 3.64 VDC from the junction to ground I= 28.24ma...I guess I don't know what effect the LED will have on the circuit and I don't understand how to find the...
  22. W

    Solving voltage divider involving capacitors

    Homework Statement Given ZV1 = ZV2 = 100Ω, ZCCV = ZCV = 2000/j = -2000j, and VV/VC = 0.04789. I'm trying to get the given VV/VC result. Homework Equations I know that 1/ZV = 1/ZV1 + 1/ZV2 + 1/ZCV VV = ZV / (ZV + ZCCV) * VC The Attempt at a Solution 1/ZV = 1/ZV1 + 1/ZV2 + 1/ZCV = 1/100 +...
  23. F

    Voltage drop across voltage divider

    Homework Statement A voltage divider with two resistors R1 and R2 is given. The output is connected to a transistor so VB is always equal to the base emitter voltage=0.7v. Homework Equations How can i explain physicaly (wath happens to the electron flow and such) why when R1 is verry high, VB...
  24. P

    Can a Bridge Voltage Divider be Used to Calculate Voltage Gain?

    Good morning,I'm french and I need help for this exercice. It's a exercice it is an exercise on the voltage gain,and on the first scheme there are the correction of my teatcher,but I but I was wondering if we can't calculate the voltage gain with a bridge voltage divider like I did.(It's in...
  25. A

    Frequency response of "purely ohmic" voltage divider?

    I am trying to understand why/when a purely ohmic voltage divider (impedences Z1 and Z2 are both resistors) would have a delayed response for high-speed, transient changes in an input voltage? Whether the input is high-freq AC, or simply a square wave with a sharp rise or sharp drop, I've been...
  26. J

    What adapter do I need before moving to America?

    Hello, I don't know if this question is appropriate for the forum, but I didn't know where else to ask. This is my situation: I'm soon moving to America and I'm taking my Sony Vaio laptop with me. In its battery the laptop says it works with 100V-240V and 50/60Hz which means that it will be...
  27. C

    V-i characteristics for voltage divider with current source

    This is a problem from Foundations of Analog and Digital Electronic Circuits by Agarwal & Lang, I'm going through it by myself, I'm not in a course, so I'm depending on you friendly forum people for help! I really like this book but it has a lot of errors, perhaps this is another error. 1...
  28. S

    Simple Voltage-Divider: Design the voltage divider to provide 5V output

    Homework Statement The attached figure shows a simple voltage-divier connecting a dc voltage source to a variable resistive load. Design the voltage divider to provide a voltage of about 5V (+/- 10%) across the variable load. The load-current demand varies in the range of 0 to 5mA, and the...
  29. Jewish_Vulcan

    Understanding Voltage Dividers: Polarity and Voltage Reduction

    What polarity does the output of a voltage divider have?, do the resistors only decrease the original voltage?
  30. S

    Where Should the Slider Be Positioned on a Loaded Potentiometer?

    Homework Statement The problem that is that of a loaded potentiometer and the position on the slider. The question is that a 10k Ohm potentiometer is connected across a 9 volt dc supply. Across the bottom part of the POT a 5k Ohm resistive load is connected which has 3 volts developed across...
  31. F

    Drift tube ion mobility spectrometer

    Hello PF, thanks for having me here. I am working in chemistry and we are building a atmospheric pressure drift tube ion mobility spectrometer. The drift tube consists of 20 stacked stainless steel electrodes insulated by PTFE spacers connected via a resistor chain (voltage divider) to produce...
  32. O

    Voltage divider rule simple question

    Homework Statement See picture.Homework Equations i=v/R v*(r1/(r1+r2))The Attempt at a Solution My question is about the solution in the picture. According to the solution, v*8/(8+16) and v*8/(4+8) equal both respective sides of the circuit A and B. My question is, why is this true? Why...
  33. P

    Voltage divider data is a problem

    Homework Statement We did an Experiment on a voltage divider and a resistive voltage divider. we had to meassure the voltage in dependency of the resistence. we did divide every meassure by the main voltage or main resistance to fit it into one plot. For evaluation i have attached the plot on...
  34. V

    Voltage Divider vs Voltage Regulator?

    I have two questions. 1. A lot of voltage dividers are wired up like this: Is there any reason why they can't be wired up like below? 2. When should a voltage regulator be used instead of a voltage divider?
  35. S

    Voltage Divider Bias: 4 Resistors, Base/Emitter, Collector, Stabilization?

    why do we need 4 resistors?we are applying voltage across base emitter junction.Why do we need a resistor for collector side.One more thing how does the resistor across emitter provides stabilization?
  36. A

    Voltage divider circuit and the Pull-down resister.

    Am reading pull-down resister herehttp://www.doctronics.co.uk/voltage.htm. PART-1 The circuit schematic of a light sensor using a voltage divider circuit is as shown: http://www.doctronics.co.uk/images/vdiv4.gif LDR has a resistance of 500Ω, 0.5kΩ , in bright light, and 200kΩ in the...
  37. M

    Three layers of a capacitor - Voltage divider + field strength.

    Homework Statement In a plate capacitor, the plates has a area of ##100cm^2## and a distance of 3mm. The insulation between the plates is a 1mm glass plate (εr = 10), a 0.5mm thick mica plate (εr = 5) and the rest is air. The insulation layers is parallel with the capacitor plates. The...
  38. M

    Voltage divider (circuit analysis)

    How am I suppose to use voltage divider to solve for V1? The first pic is the original pic The second pic is me solving for V1,Vx, and V2 The third pic is and equivalent circuit of the first pic... I did this to reason that V1 is the voltage across the 10k ohm resistor. Therefore using...
  39. PsychonautQQ

    How does a voltage divider work with a resistor and capacitor in an RC circuit?

    Is it possible to make a voltage divider split a DC power input between a resistor and capacitor? If so, does anyone have a good way to calculate vout as a function of time? Thanks :D
  40. G

    Engineering Electrical Engineering - Circuits - FET Transistor - Voltage Divider

    Homework Statement Find the voltage gain A_{v} http://imageshack.com/a/img692/3117/qkwp.png Homework Equations The Attempt at a Solution Is this the correct small signal equivalent? http://imageshack.com/a/img203/5812/1yfe.png I'm trying to find the output impedance...
  41. PsychonautQQ

    Variable Resistors in a Voltage Divider

    My textbook says that in a voltage divider (voltage source Vin, then a resistor, then another path that leads to Vout, Resistor two, Ground, that it is a bad idea to use variable resistors for BOTH of the resistors (but it is okay if you just do one or the other). Does anybody know why?
  42. M

    Voltage Divider: Solving for V in Series Circuits

    The voltage divider technique was derived from a circuit where the resistors and battery were in series. I want to focus on the the variable V in the following formula. And I only want to focus only on circuits whose elements are all in series with one another (No current division) (VRn =...
  43. P

    Engineering How to Design a Voltage Divider Circuit for Multiple Voltages?

    Homework Statement The memory components in a personal computer require voltages of -12 V, 4 V and 12 V all with respect to a common reference terminal (you can assume this to be the ground). Design a circuit to achieve this if the total power supplied to the divider circuit is 80 W and the...
  44. K

    Engineering Intro EE - Voltage Divider Design circuit

    The link is an image with the question and circuit representation: http://i49.tinypic.com/2mmwg8l.png Here are the equations I used: V_out/V_in = R_2/(R_1 + R_2) {using the node method} R_thevenin (R_th) = R_2*R_1/(R_1+R_2) And given the conditions => 10 < R_th < 30...
  45. E

    Proving the voltage divider rule?

    What SIMPLE method would you use to prove that series circuits are voltage dividers, while the current remains constant? Also What Simple method would I have to use to confirm that parallel circuits are current dividers, while the potential difference remains constant?
  46. M

    Voltage across a load resistor in a Voltage Divider Circuit

    Homework Statement Show that V across Resistor Rkohms is: (11R) / (3.96 + 4R) V The circuit is a 5V cell in series with a 1.8k resistor. Following the 1.8k resistor are a 2.2k and Rk resistor in parallel with each other. The wires then rejoin and return to the cell.Current through the circuit...
  47. Femme_physics

    Voltage divider - Looking for a reference with respect to Vout resistnce

    In voltage divider, how high must the resistance on Vout be so that voltage divider can be used according to convention? I'm looking for official references.. If anyone can help I'd appreciate it.
  48. G

    Question about voltage divider rule in series-parallel circuits.

    Say a circuit has a 9V DC supply, a 2 ohm resistor in series with it and also a parallel combination of two 1 ohm resistors in series with it. So a simple series-parallel circuit. What I don't understand is why the voltage drop across the 2 ohm resistor isn't 6V and the voltage drop across both...
  49. L

    BJT voltage divider bias beta variation

    Homework Statement Given, β=100, Is = 6E-16 See attachment. a) Find min value of Rb such that the BJT is in active region b) For the Rb found, what is the base-collector voltage if β=200 Homework Equations The Attempt at a Solution Assuming, VCE min for active region operation...
  50. L

    What is the impact of the beta dependence on a BJT with voltage divider bias?

    For a BJT with voltage divider bias (but without emitter deneration resistor), what is the beta dependence? Ib is (Vth-Vbe)/Rth [where, Vth and Rth are thevenin equivalent of the divider) Ic = β * Ib The above is almost same as just base bias, where a resistor from base is collected...
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