Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.

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.

Filter by
Sorted by
Tagged with
8
votes
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 ...
1
vote
1answer
348 views

10-bit digital representation with SPDT switches and voltage division

I'm completely new to electronics, and have been trying to come up with a way to connect 10 SPDT switches to a single analog pin on my Ardiono Mega 2560 (and off course connected to 5V and Ground). ...
2
votes
5answers
717 views

Characterizing raw op amp gain

I thought as a first exercise in op amps, even before setting up a feedback circuit, I would determine the gain of the raw op amp. I tried with an LM324 and an LM358 which should be essentially the ...
5
votes
2answers
228 views

Scaling voltage to meet two conditions at once

I am using an IC (STM6600) which, among other functions that I need, is also capable of Undervoltage Monitoring. It works like this: The IC monitors VCC in comparison to two thresholds, V_Low and ...
7
votes
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 ...
0
votes
1answer
452 views

Getting 3.3 (V) from a 5(V) rail - Emitter Follower, or something else?

I am using a Bluetooth module (RN-41 SM) that is spec'd to run at 3.3(V). I can operate this module at 5(V) however, due to another part of the circuit, I need to run the micro controller at 5(V) ...
4
votes
2answers
4k views

Voltage divider for Xbee's ADC - what resistor values?

I have an analog sensor which outputs a value in range 0-3V depending on soil moisture. The Xbee's ADC requires a value between 0 and 1.2V. I was thinking about using a simple voltage divider: ...
13
votes
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 ...
2
votes
1answer
382 views

Circuit Nodal Voltage

I have a voltage divider feeding into an op-amp voltage follower buffer circuit. I'm trying to calculate the voltage level at the non-inverting input of the op-amp vs. the source voltage. The possible ...
1
vote
1answer
709 views

Creating the proper Vref for a thermistor

I have a 10kΩ @ 25°C NTC thermistor for temperature measurement. Problem is, I only have 3.3 V on the board and the ADC inside my micro-controller has a Vref of 1.6 V. I tried to make a ...
2
votes
2answers
2k views

Measuring Power Amplifier with Sound Card

I'd like to measure the frequency response of my power amplifier, while it is connected to a loudspeaker. The power amplifier outputs at +- 50V, and I think the maximum input of the sound card is ...
0
votes
1answer
631 views

How to reduce voltage from a high speed buffer?

I am using this buffer to connect signal between 2.5 V and 5.5 V to a 3.3 V microcontroller. The problem is I will get a 5 V output and my microcontroller doesn't have 5 V tolerant inputs so I have ...
5
votes
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
votes
3answers
2k views

80's Cassette Line to Microphone Level for iPhone

This is a followup question to this one: Using an iPhone as a cassette recorder for 80's home computer I'm trying to record from an 80's home computer (a Microbee) into an iPhone. Although I ...
1
vote
1answer
710 views

Ripple factor detection and measurement

How to measure ripple factor automatically for a pulsating dc output(0-300 v)?
1
vote
2answers
1k views

Converting Headphone-Out to Mic-In Using a Potential Divider

I need to record audio with a device that only has a mic-in which is heavily amplified. I built a potential divider with R1 = 10 kOhm and R2 = 4.7 kOhm to get a factor of about 30%. I chose the ...
8
votes
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 ...
0
votes
1answer
251 views

Camera circuit with different voltage requirements on arduino

First off - i'm an EE noob, but i've muddled my way through a number of arduino projects, so have some experience there. I'm building a breakout board for a CMOS camera sensor for use with an arduino ...
3
votes
4answers
9k views

Lowering 3.3V to 3V

I am attempting to lower a 3.3V source to 3V for use with a sensor (which has a rating of 3V +/- 0.1V). Based on the other answers in here, I believe that placing two resistors in series would achieve ...
2
votes
1answer
10k views

What are the advantages and disadvantages of using signal diodes instead of resistors?

In the past to create voltage dividers or protect against back emf I have used resistors, but reading about signal diodes those situations are given as examples. I can't really comment on the inductor ...
3
votes
3answers
1k views

Current Drain on ADC

I am looking at a MCP3008 datasheet and it says that it has a maximum current drain of 150uA, and a typical current drain of 100uA. I am building a voltage divider to knock down 96V to 3V. As this ...
0
votes
1answer
115 views

Generating three voltages with a MCU

I'm going to try and generate black and white NTSC video, using a micro-controller. According to this: https://instruct1.cit.cornell.edu/courses/ee476/video/ It is possible to do it using two pins ...
1
vote
1answer
930 views

how to find minimum acceptable current through voltage divider driving transistor

I'm using a BC557 transistor to control a LED and a uC to control the transistor. The transistor itself is controlled using a voltage divider. It was suggested to me to use resistors around 100K + ...
2
votes
4answers
2k views

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 ...
8
votes
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 ...
42
votes
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 ...
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 ...
1
vote
2answers
641 views

How to divide signal level from function generator

I looked for this answer but was unsuccessful so I want to ask the experts here. I have configured an op amp in non-inverting mode (the first in a chain of 3 stages). It is for amplifying extremely ...
1
vote
2answers
10k views

Postive input ==> Positive and Negative output

I was watching some tutorials on thesignalpath.com and came across something that I didn't quite understand (even after it was explained). toddrharrison August 21, 2011 at 6:29 PM Answer ...
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 ...
2
votes
2answers
2k views

Confusion with voltage drop equation

I had never really thought of resistors causing a voltage drop, I have only used them to limit current to say an LED. Using something such as E = IR I can use a ...
13
votes
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=...
4
votes
2answers
8k views

Is this 7805-based design correct?

I found this design on internet: It is said to be a regulated power supply with variable DC output 5-15 V, 400 mA. My first question: Is this design around 7805 correct? I am asking because it doesn'...
5
votes
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,...
4
votes
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 ...
3
votes
3answers
2k views

LPC2148 ADC problem with voltage divider for battery

edit: solution found with our new board revision; outside of careless mistakes, buffering the signal with an op amp seems to have resolved the issue (as suggested by Joshua below). I am working with ...
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: ...
6
votes
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 ...
1
vote
3answers
4k views

Resistor-only solution to split 19V 3A to 3.3/5V and 12V 2A with common ground?

I need to quickly assemble a simple thing, a LED strip driver with ATTiny/Atmega. My powersource is (as always) a universal laptop brick (17-21V output @ up to 4A). So AVR would be hooked into a ...