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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 ...

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84 views

Simple way to avoid current draw on resistor divider sense?

This is a simple, but complicated question. I measure voltage on several lines, more than 3'000. The lines can be up to 100V. I only need to measure at certain time, and would like to avoid current ...
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7answers
3k 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 ...
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2answers
139 views

What is wrong with this voltage shifter?

I need to do voltage shifting (3.3V Papilio FPGA <--> 5V RAM chip). Most of the pins are output 3.3V -> input 5V, and 3.3V qualifies as "high" to a 5V device, so I can connect them directly. The ...
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3answers
121 views

Why do designers use op-amps with fractional gains?

I often find designs like the following simulate this circuit – Schematic created using CircuitLab Where the gain is less than one (\$\ R_2/R_1 < 1\$) Why not simply use a resistive ...
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2answers
199 views

How can I isolate voltage dividers so they aren't interfered with by other parts of the circuit?

I have a small and very basic circuit that PWMs an RGB LED. It has a potentiometer to allow me to set brightness level for night time and a LDR that allows me to detect night time. I took some ...
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1answer
62 views

Invert Voltage 0-2V

I need to invert voltage from the one sensor. So the ting is that I have DC signal from sensor: 0%-100% range of 0V-2V I need: 0%-100% range of 2V-0V I have LM324 level indicator and it is showing ...
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1answer
41 views

What is the best approach to calculate the transfer function of this RC circuit?

I want to calculate the transfer function of the circuit below. I tried to calculate the equivalent impedance of each block and work my way with voltage dividers until I get to V3, but this method is ...
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1answer
44 views

Voltage Divider with low noise?

I'm working with a nano scale motion stage with high precision. To move the stage I supply Sinusoidal wave using (Agilent Keysight) function generator. This F-gen, goes as low as \$20mV_{pp}\$ in ...
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1answer
80 views

Help simply the resistor usage in this voltage summer and divider circuit

Can someone help simplify the resistor usage in this circuit? VS is a constant 5v supply. Flex is a variable voltage between 0 and 5v. The resistors above have been brute forced to achieve this ...
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1answer
44 views

Constant current circuit load and without load for voltage measurement?

How can I control the constant current block? What I need? I need to calculate voltage with constant current load (I = 100ma and after some time I need to calculate voltage without load (I = 0), for ...
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2answers
53 views

Voltage divider with pull up resistors

I'm designing a peripheral circuit between a sensor (U1) and a MCU (U2). U1 has an open-drain output pin to indicate its status. This pin will be staying at either HIGH or LOW constantly (not ...
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4answers
203 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 ...
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1answer
56 views

Lowpass Filter and Attenuator

I am designing a circuit to power a brushed DC motor. The motor will be given 24VDC, modulated with PWM. I would like to have an analog voltage sense capability for use with my Atmel ATmega328P @ 3.3 ...
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2answers
78 views

How to solve a a full wave rectifier with two diodes and a ground in the middle?

This is the problem I am trying to follow along with the solution but I don't understand what is happening, how do I handle the random ground in the middle?? is the node between d1 and d2 40Vpeek and ...
2
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1answer
67 views

Are resistor networks appropriate for voltage divider?

I need to make 9 voltage dividers in order to connect 9 resistive sensors to the analog inputs of an Arduino board. I was tempted to use a 10K resistor network to individually ground the inputs but ...
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4answers
124 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 (-...
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1answer
38 views

Optimization voltage divider measurement

How to design a voltage divider to optimize the measurement error? Intuitively I would take the same ratio $$\frac{load}{divider} = \frac{divider}{measurement}$$ As follow: the voltage is roughly ...
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2answers
36 views

Is my solution to prevent leakage between power rails correct?

I have two boards with identical comparator circuitry (shown below). I want to detect in each board when the other is plugged in. My concern (in the picture) is that when I connect the two boards if ...
2
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3answers
116 views

Can I convert 72V to 12V using potential divider?

In our automation project, we'll be using a buck converter to convert the DC voltage from 72V to 12V. This method of conversion is quite expensive!! We are converting the voltage to power the ...
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2answers
27 views

Measuring battery voltage in PV scenario with MPPT charge controller with inverter

So I'm doing a PV project with wifi enabled statistics. I'd like to see the watts coming in and out and the battery charge level, estimated battery charge and discharge time. I'm designing PCB to ...
0
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1answer
36 views

Protecting 0..10 Vdc PLC input from voltage divider failures

I'm working on an off-grid PLC based battery bank monitor and dump load controller to replace commercial units that don't work really well with our lithium ion battery bank. In addition, I plan to ...
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2answers
301 views

How can I modify a USB cable with a voltage-divider to provide 3V? [duplicate]

I want to power a small device, that normally uses 4 AA/R6 batteries arranged in 2 pairs (so the device requires about 3V DC and drains probably 100mA or less). Is it possible to cut an old USB ...
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2answers
36 views

Driving a hobby stepper motor with an industrial PLC

I am working with an industrial PLC, the Beckhoff BX9000, with 24 V digital outputs. I am looking to drive a hobby stepper motor with Polulu's 'A4988 Stepper Motor Driver Carrier', which accepts logic ...
2
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1answer
174 views

Voltage Divider Answer

I have to calculate the voltage across R5 using the voltage divider formula but the problem is the answer is V5=2.23V (Here V5 is the voltage across R5) but according to my solution, Solution: ...
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1answer
45 views

LCD contrast switcher for 8051

I'm trying to come up with a good circuit from common parts that will allow me to set predefined contrast levels to the LCD from the microcontroller. I've seen an example on the internet but its for ...
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1answer
115 views

Voltage Divider Parallel Circuit

I have to find voltage across R6 but the problem is, i get a parallel circuit in the end, when I solve the circuit i get, R2345=76.67ΩR16789=96.059ΩTo apply voltage divider formula I have to get ...
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1answer
42 views

Dynamic range of voltages for ADC input controlled by software

I'm trying to build an interface that can take the readings from level sensors and provide a small enough voltage that a 3.3V microcontroller can read. I've done this successfully using the following ...
0
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1answer
62 views

12V potentiometer

I am trying to control the power of a vacuum pump using a 10k potentiometer with 12v as its input source. I've tried wiring it (with the know facing you)with the first lead as ground, second one being ...
0
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1answer
50 views

Would a bridge rectifier allow to detect µs-scale pulses of either polarity

The incoming signal is ground-referenced and consists of short (a few µs each) pulses at >150V. The signal is at ground potential the rest of the time (the "duty cycle" is low), and is of low ...
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4answers
1k 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. ...
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1answer
50 views

Measuring input voltage with 3.3V ADC MCU

I am designing my very first DC motor driver circuit. Right at the start, I want to be able to measure the input voltage to the system. The system supposed to work with external DC power supply from ...
0
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3answers
115 views

GPIO state of MCU (AVR) with no supply voltage

In general: what state do the GPIOs of a MCU (an AVR in my case) have when there is no supply voltage and the MCU is "off". Am I right that the pins are floating as there isn't any "reference" for the ...
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1answer
57 views

Active analog attenuation with OPA2340

I wish to have active analog attenuation circuit. Following this page, I got myself some OPA2340. I use the B-side to keep the numbering somewhat intact. I go with the design on Figure 16-2 (p. 14/...
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2answers
38 views

ac voltage added to dc base line

I began to read up on transistors, which led me to this post on electronics stackexchange. At the end of the original post, the question asks "the voltage at the base would be a sine wave with the DC ...
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1answer
67 views

Not getting expected voltage at LED

I recently picked up and arduino nano kit and messed around with all the simple projects. I dont have much EE experience besides those so I have a question that might be pretty basic. I am trying to ...
0
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1answer
69 views

Using a voltage divider with buried zener voltage reference

My plan in the below circuit was to use a voltage divider from a Max6225 2.5Vref, to get 2V and 1V from it in order to use the full 16bit bipolar scale of the ADS1115s, but I'm getting strange ...
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0answers
26 views

LIS3DH ADC reading 0 ~ 30v

LIS3DH accelerometer includes 3 auxiliary ADC (ADC0 ADC1 ADC2). but ADC channels are able to read voltage 900mv to 1800mv which corresponds to (-32512 to 32512). but I would like to read voltage 0 ~ ...
4
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2answers
808 views

Simple Op-Amp setup for current sense has a strange working range

I am using a LM358D dual amplifier at the moment and my goal is to measure over-current on 2 motors. Before I'll be doing that, I made a test setup to test the equations and check the output signal of ...
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0answers
34 views

Voltage Divider for Comparator Threshold

I am trying to understand how the voltage on the negative pin of U2A of the below circuit is 1V/2.4V. From the author: "Threshold signal is 0V/5V but it changes ...
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2answers
52 views

Unable to start calculating this voltage divider

I'm trying to solve all kinds of voltage dividers for an upcomming exam, but I'm stuck in this one. I've solved it in LTSpice, but I cannot solve it on paper. LTSpice showed me, that the Ux=3V, but ...
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1answer
92 views

Deducing the value of a variable resistor in configurable voltage divider

Two variable resistors (RS & RE) and one static resistor (RC) are connected to a high impedance input analog input pin of a micro-controller. The static resistor is connected to ground and the two ...
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3answers
109 views

What is the best way to step my signal from 5V to 3V3? [duplicate]

I have some analogue signals between 0 and 5 Volts being fed from a multiplexer into another board that only accepts signals up to 3v3. What is the best way to step down the voltage? The signal ...
4
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4answers
2k views

Creating required voltage across a device using basic electrical principles [duplicate]

Let me explain what I mean by an imaginary case. Let's imagine a 10 V battery in series with two resistors equal in resistance value. The voltage in between those resistors is 5V according to the ...
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2answers
102 views

How are voltage dividers used in circuits?

I am a newbie and wanted to understand in simple terms how a voltage divider maybe used to for instance, power 2 different LEDs of different voltages if they were within a circuit. The main issue ...
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1answer
99 views

Voltage divider which will work for low and high frequency signals

I am using the below circuit (fig1) to step down the voltage, which I found on the internet. I want this circuit to be operate properly from 1 kHz to 50 MHz. When the input is a square wave. But this ...
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1answer
56 views

Inconsistent DC Input Resistance in Black Box [closed]

How It's Measured I have a circuit (can be assumed as Black Box) I want to measure the input resistance (R2) at DC. I do the common method of using a signal (V1) with a known source resistance (R1) ...
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3answers
124 views

Voltage divider as supply voltage [duplicate]

Is voltage divider is a good option for supply voltage to an IC ? I am working with a 555 timer, MAX232 ,an Inverter SN74LVC and with a 12V relay. I heard that voltage devider is not a best way to ...
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1answer
87 views

Measuring 200 volts safely

While I can measure line voltage safely, I need to write a procedure to have someone else measure the voltage. The load is pure resistive,and I want to measure the voltage across it, with a battery ...
0
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1answer
79 views

Connecting an analog temperature sensor IC to an ADC input of a microcontroller

I am trying to connect an analog temperature sensor LMT84 (http://www.ti.com/product/lmt84) to a micro controller (3.3VDC) using its ADC pin which is 1.4V tolerant (max). My Vcc is 3.3V, ADC max ...
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4answers
92 views

Voltage Dividers for a beginner (with respect to soil moisture sensors)

I've just started with electronics and want to make an analogue soil moisture sensor (with Arduino). When I looked online for an explanation of the working, every site said that it works as a voltage ...