# Tagged Questions

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 resisors 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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### low resistance material used for sensing

I'm researching conductive fabric with a surface resistivity <0.5Ω/m2 (unstretched). I've used a voltage divider setup to connect with an ADC pin of microcontroller (ATMega/Arduino board). ...
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### Voltage divider circuit pnp transistor

From the above circuit I wanted to know If the switch is in position 2, will the 100kΩ resistor be parallelt to the resistor R? Is the power dissipated by the transistor equal to Vce*IC
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I have a TMP36 connected to an analog pin of an Atmega328p-pu on a breadboard (with Arduino bootloader), everything is powered w/+5V from an Arduino Uno R3 (which is used as a programmer). The ...
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### Constant Sum Voltage Divider With Thermistor/Temp Sensor

I need a circuit with a thermistor/temp sensor that will essentially emulate a pot. In other words, I need a voltage divider that varies with the resistance of the thermistor/sensor, but keeps the ...
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### How would i go about finding Rl when rl is r3

How would i go about finding Rl :/ I'm so lost iv looked for examples and all they have done is confuse me
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### Measure 0-10V using Arduino

A thermocouple amplifier outputs a voltage range of 1.2V to 8.8V for the temperature range -260C till 1380C when using a K-type ...
257 views

### voltage divider circuit for dc motor

I would like to run a 6V dc motor using a 9v battery supply. The motor specification states that current is 150mA at 6V which I calculate to be a resistance of 40 ohms (when I measure the resistance ...
371 views

### Why should we need DAC ICs?

Please look at the schematic below. This is a very simple resistive adder that works fine with any standard ! (TTL,CMOS,...) or any arbitrary voltage that is fed into it. On the other hand as there is ...
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### Schottky diodes for voltage conversion

I recently bought a DE0 FPGA board with GPIO headers. The schematics shows that some of them are protected with BAT54S Schottky diodes. Does it mean that if I input 5v logic level they will be ...
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### How to voltage divide down a single ended analog signal? [duplicate]

I have a 0-5V Single ended analog signal coming into an A/D pin on my microcontroller. The Micro pin can tolerate only 0-3.3V analog signal. What can I do? Can I just add a simple voltage divider ...
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### Run a 5VDC 0.2A fan from a 24VDC 3.75A power supply - Help Needed

I am working on a project that is using a 24VDC 3.75A power supply and would like to have a small fan (5V 0.2A) to cool the amplifier and switching circuits within an enclosure. Could someone help ...
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### How do I simplify this circuit to find resistor voltage?

In my circuits class, I am presented with the following exercise. simulate this circuit – Schematic created using CircuitLab The problem is to find the voltage across resistors A and B. ...
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### How do I provide 7 volts from a 12 volt source?

I want to power a GHI Panda II single board computer that has a GHI FEZ Connect shield attached for Ethernet access. GHI Documentation specifies 6.5 V to 7.5 V input for the Panda and shield that can ...
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### What are the advantages of using a voltage divider?

If you had a circuit hooked up like this: simulate this circuit – Schematic created using CircuitLab it would be using a voltage divider, as Vin(R2/(R1+R2)) is the voltage divider rule. ...
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### Which one is better as voltage divider: resistive, capacitive , low pass filter,…?

There are different types of voltage attenuators for AC signals ( a short explanation is here). The most well known is a resistive one. Others like capacitive, inductive or low pass filters are ...
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### What resistor values to use in a voltage divider?

I understand that the output voltage is determined by the ratio between the two resistor values, and that two 1 kΩ resistors will output the same voltage as two 1 MΩ resistors (correct me if ...
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### Which is the correct voltage reference for a single supply instrumentation amplifier?

I'm working on using the TI INA333 in a single 3v supply configuration. I need to create a "mid supply" (half V+) for the REF pin. I have thought of 3 ways to do this: Voltage divider with ...
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### inverting op-amp circuit

Why is -Vout equal to the voltage going through Rf? here is a link to a site which explains the inverting amplifier circuit but I couldn't understand why this is.
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### 3V power rail from 5V

I've mistakenly ordered some 3V PIC18 L F14K22 instead of the 5V 18F14K22. 3V output is fine for the designed circuit but I need to make a 3V power rail from the available 5V rail. Since only a ...
112 views

### replace buttons in voltage-divider with mosfets

I have this voltage divider (each press of a button generates a different voltage) I want to be able to enable the buttons with a +5V signal. I tried to replace the buttons with 2N7000 n-channel ...
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### Voltage Divider Variation

Well, we all know that in a voltage Divider circuit like this, Output voltage is: (R2xV1)/(R1+R2) Can someone tell me how do you go about finding voltage in this? I want to find out voltage ...
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### Using/Charging a backup battery in a 12VDC circuit

EDIT: I've revised the circuit in response to comments from Andy aka. I have also updated my questions to make it more clear what I am asking. I'm leaving the top paragraphs for completeness' sake. ...
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### Voltage Divider Question

Hi I was building a Voltage divider for supplying a fixed voltage to a load, now if the device is a motor, which practically has some resistance, then is it true that the voltage it gets will be ...
210 views

### 7-segment output: 4-6V, LCD input: 3-5V. How to convert?

Problem: I am thinking of using a chip that gives out 4-6V on 7-segment output pins but the LCD only wants 3-5V input, so I need to convert somehow. The display is a TN type, drawing virtually no ...
164 views

### Effect of a transistor on a voltage divider? (or vice versa)

I'm learning about transistors and am trying to make a basic circuit that uses a photoresistor as a sensor to turn an LED on and off depending on light conditions (the 150kOhm resistor is where the ...
490 views

### How to connect Raspberry Pi to House Alarm Serial Bus (DSC Keybus)

I have a DSC 1864 House Alarm and I want to connect up my Raspberry Pi's GPIO to the Keybus (a serial data communication protocol used by the alarm). I would say my knowledge of electronics is novice ...
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### 230V AC / 460V DC Optocoupler using Led and Voltage Divider

I am building a primitive optocoupler to sense if a bulb has blown/if current is flowing. It receives either 230VAC or 230VDC (rectified..) as supply. I have calculated and built a voltage divider as ...
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### Limiting the input current with voltage divider

I would like to measure two signals with a microcontroller ADC: 0 to 5V, 5MHz -36 to +36V 100Hz simulate this circuit – Schematic created using CircuitLab I want to draw as small ...
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### Choosing values of resistive divider, versus pullup resistor value

I have a slight Catch-22 with my circuit portion shown below. The ADM6320 is, among other things, an undervoltage detector with factory threshold of 2.93 V (thus Reset output pin toggles when VCC ...
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### Diode causing voltage drop

I'm planning to wire a sensor (MQ-7 - Carbon Monoxide sensor) into my Arduino and this sensor requires a voltage of 5V during 90 seconds and then a voltage of 1.4V during 60 seconds. The schematic I ...
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### How to power a voltage divider with 2.1V

I have a 3.3V circuit with an ADC chip that reads values between 0V and 2.1V, that means anything above 2.1V will return 2047. If I use a voltage divider with the Vcc power supply, I would lose a lot ...
187 views

### Using an Op-amp as comparator

I have a dual op-amp that I want to use as a comparator: Vin should be compared to Vref (1/2 VCC). This is the circuit that I am using (as I have a dual op-amp, I am using a voltage follower on the ...
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### Voltage Divider not functioning as expected

I've set up a voltage divider to take a 5V signal down to 3.3V. I'm using resistors with values of 6.8 kΩ and 3.78 kΩ. When I use a 5V source straight from a wall wart, the voltage divider works ...
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### How should I choose the resistors in a voltage divider?

I would like to measure tree signals by using a ucontroller. the signals are between -5V to 5V 0V to 2V -20V to 20V The frequency of the signals are between 1MHz and 5MHz. The ADC range is ...
124 views

### Auto-ranging A/D conversion?

I often find the Arduino 10-bit A/Ds lacking in resolution for my needs. I much prefer auto-ranging voltmeters. Can I play the same game? Can I divide my target voltage range into segments to ...
158 views

### Generating a 10 volt rail from a High Voltage Supply with unknown Ground Potential

I have a sticky situation where my power supply is coming from a charged capacitor with 200 volts across it. Because of the way it was charged, I can't guarantee that the negative side of the cap is ...
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### Help with this “Make” tutorial

I'm a software guy and am dabbling a bit with arduino recently. I don't understand many things when it comes to taking a circuit board schematic and doing it in real life. For instance, at this ...
2k views

### MOSFET as a voltage controlled resistor

This question might be too localized, but I try. Is it possible to replace a variable resistor by a MOSFET, under conditions shown in the following schematic? If yes, can someone propose a MOSFET ...
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### Voltage Controlled Attenuator

I'm trying to create a DC voltage attenuator which linearly scales the loss relative to an applied control voltage "Vc". In other words, K = Vout/Vin is a linear function of Vc. Vin is guaranteed to ...
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### Switch transistor with a low voltage and current

I'm designing a circuit that will use a combination of switches and resistors to allow a microcontroller to identify which switch was pressed based on the voltage read and perform a switch-specific ...
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### Measure current on a constant current source

I need to measure current on a constant current source(LM317), because I am using a 3v3 chip I also need a voltage divider to read it. Will this circuit work Or will it wreak havoc trying to increase ...
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### Replicate thermistor behavior for second sensor

I'm working with an R/C electric motor that has a 10K thermistor sensor built into it, which is connected to a speed control that has basic thermal protection. I would like to build a secondary sensor ...
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### When use Voltage divider in circuit analysis

I am trying to find the voltage in R2 with voltage divider, this is the schematic: simulate this circuit – Schematic created using CircuitLab but I can't, and I don't know how to apply ...
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### Finding values of LRC circuit when frequency is given

I am trying to solve the following question. The original question is: The given impedances of the series LRC circuit are established at an angular frequency of 2000 rad/s. Calculate the ...
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### easiest way to detect a switch change using an arduino

I have a pinball machine thats an old electro mechanical type. I want to add LED's and do some fancy programming on an Arduino to animate the lights according to the score value of whatever target ...
701 views

### Low current battery monitoring

I want to run a micro-controller from a 1S lipo through a 3V linear regulator. I need to measure the battery voltage however. The problem with using a voltage divider is that it would drain the ...
394 views

### Improving absolute precision of ADC to balance battery voltage

I plan to use a relatively high-end microcontroller (Piccolo TMS320F28035, 12-bit resolution, +/- 4LSB offset, +/- 60 LSB gain) to measure voltage across stacked battery cells and control associated ...
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### Taking the limit of voltage division equation

I'm required to take the limit of the voltage division equation(internal voltmeter resistance included as Rm) when Rm goes to infinity to show that the limit equals to the basic voltage division ...