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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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Isolated voltage sensing

I'm in the process of building a battery powered, uC controlled power supply. I'm using a bluepill basically and an xl4016 buck converter module. To my assumption I can just tap in his regulation pot ...
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Why is a voltage divider used when reading analog sensors?

So when reading sensors (ping sensors/light/pressure/etc...) I notice they always use a voltage divider with resistors before running the input into the ADC input of a microcontroller. Why can't we ...
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Issue having 4-20 mA interface with ADS1115

I need to make a 4x 4-20mA measuring circuit with ads1115 (VDD = 5V) 4 channel 16bit ADC I set ads1115 PGA to 4.096 gain and set circuit as below. once I set this 32000 ADC levels--> 4.096V--> 0....
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77 views

1M Ohm Thermistor Circuit voltage drops not adding up

The circuit is wired as follows ...
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1answer
64 views

What is function of the resistor in series with bypass capacitor in npn transistor amplifier?

I am new to electronics and recently I was learning about npn transistor as an amplifier. I tried to build one in ltspice XVII. This is my circuit diagram: but the output was not as expected as ...
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2answers
122 views

Are there special rules for voltage division of a high speed clock?

High speed signals require special care in PCB layout to prevent high speed effects like ringing and overshoot. This obviously applies to clock signals as well. Provided that one has a high voltage ...
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1answer
70 views

Why not use the same size resistors for each stage in a Kevin-Varley divider?

I was thinking of building myself a Kevin-Varley divider as described for example in this article about a mini metrology lab in the March 1996 issue of Electronis Now by Conrad R. Hoffman. The normal ...
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34 views

Drive 433Mhz emitter and Attiny with two coin cells

I would like to detect when the postman put mail in my box, so I was thinking about a simple attiny with tilt sensor (which would wake up the attiny) and a 433 MHz emitter: The problem is that one ...
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Why is the source voltage 1/4 of the supply voltage applied to the drain in a voltage-divider JFET circuit?

According to a Junction Field Effect Transistor (JFET) article in ElectronicsTutorial, the voltage across the source resistance is equal to 1/4 the supply voltage applied to the drain/gate for a class ...
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Solving the MOSFET, using KVL?

The question is Find VD and ID? The FET has Vth = 1.0 V and k(w/l)= 1.0 mA/V2 and λ = 0, VDD = 5 V. My question is can I use KVL like this Vdd - R1 ID - R2 ID - R3 ID =0 rearranging for ID = 11/5? ...
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63 views

Voltage divider to drop volume of one speaker by 1.5dB

I have a a balanced stereo audio source, being fed into a headphone amplifier. Both source and amplifier are connected via a pair of 3-pin XLR cables, one for each channel. The amplifier then outputs ...
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Would a voltage divider work to lower the output voltage in this case for this open collector chip?

I want to interface the output Vo of this chip to a trigger input of a DAQ device. Here below is the chip which is open collector output so There will be a resistor between Vcc and Vo: And the specs ...
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71 views

BJT AC Analysis using r_e model

This is a picture of a Common Emitter Voltage Divider bias and it is been modelled using a CCCS and a diode resistance using the r_e model. Now my doubt is that I get problem in finding the input ...
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924 views

Ways to power an Arduino from 24 VDC

I want to power an Arduino (Wemos D1 Mini) with 5 or 3.3 V from my garage door opener, which has 24 VDC available. As far as I understand, this can be solved in the following ways: Step down buck ...
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1answer
52 views

Voltage divider Vout not powering ESP8266 [duplicate]

I have an input voltage of 12V from my power supply and i need 6V to feed into the ESP8622. I was giving it all the 12V but the wifi module becomes increasingly hot with time and so i decided to have ...
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3answers
49 views

Loading effects of a signal source

I'm reading "The Art of Electronics" (3rd edition) by Paul Horowitz and Winfield Hill. In the 2nd chapter on BJT (page No. 79, section Emitter follower). The author says: ".. In general, the ...
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1answer
93 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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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
156 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
133 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
213 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
66 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
44 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
63 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
83 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
52 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
70 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
226 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
57 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
90 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 ...
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1answer
74 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
127 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
41 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
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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 ...
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3answers
123 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
38 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 ...
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1answer
37 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
416 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
46 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
179 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
47 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
156 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
53 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 ...
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1answer
98 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 ...
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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
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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
54 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
134 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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65 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
40 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 ...