Voltage divider Definition and 91 Threads

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. Q

    Create a Simple Fire Alarm with Voltage Divider and LED Circuit

    Hi everyone, I'm new to circuits, and was thinking about using a voltage divider circuit to make a very basic "fire alarm." I've attached an image of what I was thinking. The top resistor is a thermistor. I'm having trouble figuring out what this circuit will do. My...
  2. V

    Designing a Variable Gain Voltage Divider Circuit

    Homework Statement Using a 100-kOhm potentiometer and suitable external resistances, design a voltage divider circuit such that varying the wiper from end to end varies the gain over the range: a) 0 to 0.75 V/V b) 0.2 V/V to 1 V/V c) 0.1 V/V to 0.9 V/V Homework Equations Not Sure...
  3. L

    What is the concept behind varying resistance in a voltage divider circuit?

    Homework Statement Dear Members, I have attached two diagrams found in Voltage divider topic found in web , while discussing about potentiometer . My doubt is, in the first attachment( Voltage Divider.png) when the wiper( the one with arrow mark) is moved towards the top, that is towards...
  4. 7

    Voltage divider circuit and effect on current

    Hey, Im new and this is just a simple question. I want to make a voltage divider circuit to power a 3V dc motor using a 9V battery supply. However the motor draws 0.20amps when there is no load. In conjunction with the voltage divider equation V(out) = (R2 * V(in) )/ (R1+R2) , how to ensure...
  5. J

    Annoying nonlinear voltage divider

    Hello All, I'm working with a microcontroller and want to take analog measurements using its built-in ADC. However, I want to be able to measure voltages much higher than just 0-5V. My *seemingly* simple solution to this was to grab a 500k 25-turn potentiometer which I could connect up as a...
  6. T

    Is V0 the Voltage Drop Across R1 or R2 in a Voltage Divider?

    Homework Statement This is more of a theoretical question than an actual numerical problem (so mods please move if this is in the wrong place). The circuit below was copied from my book. Ultimately we are discussing the voltage divider. The book goes on to say that V0 is the voltage...
  7. L

    Why does the voltage across R1 increase when the BJT is turned ON?

    I am trying to design a 3 Resistor voltage divider. The center resistor is shorted out using a transistor depending on the input voltage. If Vin is <1, then center resistor is not shorted. If Vin is >1 then center resistor is shorted by the BJT, so only the top and bottom resistor will act...
  8. A

    Voltage Divider - Understanding Two Circuits

    Very silly doubt...If say I had a voltage divider circuit with 2 equal Resistance say R applied between 1.V=5v and ground 2.V=5V and V=-5V Whats the answers and what the difference? I guess the answer for the 1 Q will be (5/2)... Please explain the second ...Thank you
  9. L

    Unexplained voltage loss in a simple voltage divider

    hey guys, I am currently trying to implement a voltage divider to step down from 9V DC for a digital output. I am using two resistors, 3.3M ohm & 2.7M ohm in series. When I measure the voltage across both of them using a multimeter I get 9.5V Across the 3.3M ohm resistor I get 2.2V...
  10. N

    How Can You Design a Voltage Divider for Varying Internal Resistance?

    Homework Statement You want to build a voltage divider for a product that uses as it's source a 12v battery and a non-zero internal resistance. You want to have an output voltage between 4 and 5 volts. The internal resistance varies from 5 ohms when fully charged to 100 ohms when the battery...
  11. K

    Voltage divider in transformers?

    i never heard of such a thing but what could be the circuit analysis to this? http://i.imgur.com/Zd6qn.jpg what is V1 and V2? what could make V1 and V2 not equal?
  12. M

    Engineering Why Do I Get a Negative Value for R2 in My Voltage Divider Circuit?

    Homework Statement Hello, can someone please help me create the following curcuit? Id like to know the steps so i can to solve this. I don't seem to be getting the correct answer its very frustrating because it seems so simple. please advise...
  13. D

    Measuring Voltage Divider Output with Real Voltmeters

    Homework Statement How do you measure the output of a voltage divider with real voltmeters that have effective resistances Homework Equations The Attempt at a Solution I know that for an ideal voltmeter (one with infinite resistance), the voltage divider is R2/(R1+R2), but I...
  14. T

    How Is Voltage Divided in a Circuit with 3k and 4k Resistors?

    Homework Statement Calculate the current i and the voltage appearing at X and Y Homework Equations None. The Attempt at a Solution I found I to be 0.002A and Vy = 2V, but I am having trouble with Vx Attempt: I tried getting the current that goes through the 3k and 4k...
  15. E

    Designing a Voltage Divider Circuit with a Trim Pot

    Homework Statement I need to make a circuit with a Potentiometer as a voltage divider. There is a 9V voltage source. Two resistors(in blue on the picture). The first blue line, is a 3k Ohm resistor. The second after the Turn Pot is a 1k ohm resistor. The red lines are red wire. The black line...
  16. jegues

    Voltage divider with added resistance

    Homework Statement See figure. Homework Equations N/A. The Attempt at a Solution First I did KVL in the large loop and the small loop so, KVL_{large}: i_2R_1 + (i_1+i_2)R_2 - V_s = 0 KVL_{small}: i_1R_m - i_2R_1 = 0 Using KVL of the small loop one can say the following...
  17. J

    Calculating Voltage Change in a Voltage Divider Circuit

    Homework Statement Consider the following voltage divider circuit with these values: R1= 10.0 kΩ, R3= 15.0 kΩ, E1= 13.0 V. What is the percent change in Vx when we connect a load resistor Rx = 10 R3? http://a.imageshack.us/img25/1546/circuity.th.png Homework Equations V1 = E * R3...
  18. J

    Voltage Divider: Calculating Output Voltage

    [b]1. Homework Statement A voltage divider consists of two 56kohms resistors and a 15V source. Calculate the unloaded output voltage taken across one of the 56kohm resistors. What will the output voltage be if a load resistor of 1.0Mohms is connected across the output?
  19. L

    Understanding Voltage Divider Equation in Op Amp Circuits

    Homework Statement This is not a HW question. I was watching a lecture on youtube - http://www.youtube.com/watch?v=ke3SL_R92ys&NR=1 At 9mins into the lecture, there is a voltage divider equation. (screen shot attached) In the calculation of voltage at the +ve input of an op amp, the equation...
  20. J

    Dealing with Input Offset Voltages in Op-Amp Circuits

    Hi first time poster. I'm a little stuck, through trial and error on Mentor graphics I was able to create the attached circuit. Using +&- 9V supply rails I managed to output -10mV, which I required. Now I have come round to try and work it out by hand I'm struggling to remember how! I know that...
  21. K

    Archived How to Calculate Voltage Across R3 in a Voltage Divider Circuit?

    Homework Statement I'm looking at a larger circuit, but part of the problem is clearly an application of a voltage divider. The input voltage goes through a resistor (let's call it R1, it's value is 3kohms) and then it hits a node at which point it can go through R2 or R3 (12 and 6kohms...
  22. T

    Solve Voltage Divider Problem with Vg=210V, R1=15.5kOhm, R2=66kOhm, RL=157.5kOhm

    This is the problem. Given that Vg is 210 V, R1 is 15.5 kOhm, R2 is 66 kOhm and RL is 157.5 kOhm, find the voltage "v0" (Hint: Use the voltage divider concept.) My attempt at the problem was to combine R1 and R2 through series and use RL as R2 in the voltage divider formula. The answer...
  23. T

    Calculating Output Voltage in Complex Voltage Divider

    Homework Statement The circuit below combines variable resistors R1 and R2 with fixed resistors to make a complex voltage divider. If the switch is closed and R1=8000ohms and R2 is 5000ohms, what is the output voltage. Homework Equations V=IR The Attempt at a Solution the...
  24. M

    Voltage divider; missing capacitor

    Homework Statement I can't seem to get a start on this. Could anyone provide a hint or something to get me started? Thanks...
  25. P

    How to Find Vout/Vin vs. Frequency in a Voltage Divider Circuit

    Homework Statement The problem deals with a circuit that has a voltage divider composed of an inductor L and a capacitor C in series connected to a node, one end is an open circuit with the output voltage and the other end is connected to a resistor R that is connected to ground. Find the...
  26. S

    Voltage Divider Bias: Removing Electrons from the Base

    In Voltage divider bias , we are not drawing any electrons from the base. Then how can the electron current pass through the base and go to the collector and reach the positive terminal. Only if You draw electrons from the base by maintaining the base at positive potential, then only the...
  27. A

    What is the ideal ratio for external resistors in voltage divider biasing?

    I want to know is there any constant or suitable ratio for external two resistors which we use for the base of the BJT in 'voltage divider biasing'? I have heard that the ratio of those two resistors should be something like 3.. but I am not sure...
  28. L

    What is the theory behind voltage dividers and current dividers?

    friends, what is the role of potential or voltage divider in a circuit? in an operational amplifier circuit, while applying inputs to non inverting input, when two resistances are connected are connected across the battery they said to form a voltage divider. if the first resistance is r3 and...
  29. B

    Voltage divider using capacitor question

    I'm calculating the size of a capacitance I need to drop a certain voltage at a certain current for a tube filament, and doing it two different ways gives two different answers. For example: Tube needs 13 volts across it at 0.725 amps current. I pretend that the tube's heater is a resistance...
  30. U

    Voltage divider and potentiometer

    This is so far I've learnt...potentiometer is a potential divider, it also functions to measure the unknown emf of a cell (Ex). Here is the image of a potential divider: And here is one of a potentiometer: The thing that confuses me here is that if you compare both images, you will see...
  31. B

    A voltage divider in terms of a conductance

    I am looking at the following application note that goes into nodal analysis of op amps: http://www.maxim-ic.com/appnotes.cfm/an_pk/1939/ and down at the bottom where they're analyzing the Wien bridge oscillator the equation at the negative input of the op-amp taken from the output in terms of...
  32. M

    Help me to Create a MATLAB program to design a custom voltage divider

    Input: The input values will be provided by the program customer or user Input voltage. The power that the customer or user of the program has a available to drive the voltage divider. Output voltage. The desired output voltage chosen by the customer. Maximum output current. The maximum...
  33. L

    Voltage Divider Circuits. Set Me Straight.

    Hello all. I wonder if anybody could clear this up for a beginner. In the circuit attached: Is V OUT 1 of a higher voltage than V OUT 2? Does the current travel at 9V, until it drops at R1? Does it drop again at R2 and give an even lower voltage to V OUT 2? Or does the presence of two...
  34. I

    Maximising sensitivity in a voltage divider

    Hi folks, Homework Statement We have a voltage divider (more specifically, a resistive divider), with V_i volts input and resistors R_1 and R_2 in series. The output voltage, V_o, is measured over R_2. R_1 is a fixed ohmic resistor; R_2 is a potentiometer. I'm looking for an algebraic...
  35. Q

    Understanding Voltage Dividers to Redrawing and Solving Ladder Networks

    Hello I have the figure below,and i do not understand the question..It says: Determine V0 by redrawing the ladder network above as a cascade of three voltage dividers...can someone explain to me what to do? thank you!
  36. N

    Voltage Divider Bias Under Load

    Hey, I'm kinda stuck in this odd question. I've tried searching on the Internet but haven't found much help. Basically, I have a voltage divider biased transistor. I can solve and find its Q-point without an external load, but I'm kinda confused how the circuit will change when there is an...
  37. russ_watters

    Voltage Divider Help: Solving 12V Power Supply Issues for Telescope

    I blew another 12V (13.5V actually) power supply running my telescope the other night. Primary power comes from a 17 a-h lead-acid battery in a power tank. I run the telescope and a dew heater from it and over the course of a night (10-12 hours), will drain the power tank completely. I keep...
  38. M

    Equation with a voltage divider

    The problem seems quite easy, and it probably is, however I'm having trouble understanding how I can put up an equation to solve this at all considering the examples in the book are like ten thousand times easier than the equation we're given here...
  39. R

    Voltage Divider Equation: TTL Circuit Analysis

    http://img153.imageshack.us/img153/9007/untitledvb8.png That is my TTL circuit. I forgot to add +5v and a circle at the top of the diagram, so pretend it's there. Do I have to use the voltage divider equation to get the value of Vout? (5v)(Rl)/ (Rl + Rc) where Rl = 1kohm, Rc = 100kohm?
  40. F

    Troubleshooting Voltage Divider Problem for Analog and Digital Circuits

    I designed a circuit that has an analog signal conditioning portion, and a digital circuit to make some measurements on the signal. The analog circuit is powered by 15V supplys, thus the output is a 0-15V square wave. The digital circuit needs a 0-5V input. I tried using a voltage divider on...
  41. D

    DC biasing using voltage divider

    how do I use a voltage divider to biasing a signal that goes from -5v to 5v so that it goes from 0 to 2.5?
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