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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70 views
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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6answers
110 views
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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3answers
94 views
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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1answer
37 views
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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3answers
177 views
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 ...
2
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1answer
62 views
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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2answers
86 views
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 ...
2
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3answers
164 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 ...
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3answers
190 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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1answer
83 views
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 ...
2
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1answer
200 views
Can I use a voltage divider circuit instead of a level shifter here?
I am trying to hook up an LCD module to my microcontroller, and was following this tutorial.
Notice that the three signal wires all go through a level shifter, which drops the voltage from 5V to the ...
2
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1answer
60 views
How do I measure the characteristics of a voltage divider in a QUCS simulation?
How do I measure the characteristics of a voltage divider in QUCS?
Below is what I have tried thus far, using Qucs 0.0.15 on Ubuntu 10.04
I want to measure how the voltage at the center of a ...
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2answers
88 views
How can I get 17 VDC from 25 VDC with current may up to 10 A?
I'm new in electronic and electrical circuits, so maybe my question will be naive.
I have an electrical transformer that gets 220VAC as an input and gives 25VAC as an output, and can produce 20amp ...
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1answer
95 views
Why do my 3 custom voltage pulses stop working as soon as I plug in the A1362 Hall-Effect sensor?
Why does the Vout pin in the diagram below receive 8 volts with Vcc = 0 volts, but becomes 2 volts when Vcc=5 volts. If switch SW9 is closed, circuit theory says Vout should always stay at 15 volts ...
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1answer
158 views
Opamp topology without a stable voltage reference
I have an opamp configured as a constant current sink like this:
As you can see, the reference voltage for the SENSE pin is set by the voltage divider on the left. This requires a stable voltage on ...
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0answers
47 views
What should the values of resistors R1-R6 be in order to get desired voltage pulse specified in Allegro A1362's data sheet?
I am trying to program sensitivity and offset of the A1362 Hall-Effect Sensor
by sending the following voltage pulses
VpH - Voltage High - 27 Volts
VpM - Voltage Mid - 15 Volts
VpL - Voltage Low - 3 ...
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3answers
103 views
Driving three LEDs in series with different Vf at 700mA
Given LED1: Vf = 3VDC for 700mA ---- and ---- LED2: Vf = 4VDC for 700mA
If I put LED1 + LED1 + LED2 (in series) and apply 10VDC across them, will I have 700mA flowing through them?
4
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2answers
155 views
Pull-down resistor value for FSR's voltage divider circuit connected to Arduino
I am working on a project which includes two FSRs (force sensitive resistors) connected to an Arduino Uno. I have each FSR setup as in http://www.instructables.com/id/FSR-Tutorial/?ALLSTEPS, but each ...
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1answer
322 views
how to reduce 24v to 0- 2.5v through a pot
I have a 24v dc supply and I need to give a heater a 0-2.5v variable input. I have a very limited understanding on electronics but I've read here about voltage dividers. I used a 10k pot (and the 2 ...
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1answer
95 views
Arduino Pro Micro: how to access A1
I have an Arduino ProMicro 5V 16MHz board from sparkfun.
I have a 3Cell LiPo powering the entire thing (via the relevant regulator bringing it down to 5V). This is part of a TriCopter. I tap the 12V ...
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3answers
154 views
Reduce and clip voltage of a 5Mhz ultrasonic signal from +-50V to 0-3.3 V
I know there are a lot of posts similar to this one but some differences make it worth posting it.
I’m working on a project where I have a 5MHz AC signal with the largest amplitude of +-50V. It’s an ...
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1answer
156 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 ...
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2answers
590 views
Negative Voltage Level Shifting to an ADC
I am currently building a project that uses an AD595 analog devices chip to linearize the output of the Thermocouple sensor to 10mv/deg C. This output is to be connected to the ADC input of a Zigbee ...
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1answer
120 views
How do I calculate the voltage at these locations?
I'm wondering how to calculate the voltage on the following charts (series circuit and parallel circuit). I'm interested in the math process involved, not the answer.
I'm mostly confused about how ...
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2answers
116 views
Measuring forklift battery's voltage
I'm trying to measure a fork's lift battery by an ADC.
The problem that the output voltage isn't predictable and not constant, so that I can make a constant voltag divider.
What I have measure is it ...
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1answer
125 views
Designing a PoE Circuit
I'm going to buy a PoE injector kit, and I will supply it with an AC voltage, and with ethernet cable, and at the other end I will design a seperator circuit, but however most PoE injectors just give ...
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3answers
160 views
Connecting 3.3 and 5 V devices
The requirements are different from similar questions I've found here.
TXB/TXS are expensive for my needs.
Sparkfun's logic shifter is bi-directional, while I need two uni-directional conversions, ...
2
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2answers
131 views
Increase resolution of voltage divider
I have a lead-acid battery on which I am using a voltage divider to measure the remaining charge.
Its my understanding that an example battery could discharge from 100-0% over say 10.5V - 12V.
...
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1answer
210 views
Combine voltage divider with shunt for solar monitor
I have a basic 12V solar panel system set up with a basic (non-PPT) charge controller(anode/cathode for Panels-Battery-Output). I would like to monitor/control the system with an arduino-based ...
7
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4answers
385 views
Zero or low-current voltage divider for switch identification
Is it possible to design a voltage divider circuit with switches that uses zero current, or very low current? Would it work to use a transistor to connect/disconnect the end of resistor string from ...
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2answers
156 views
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3answers
303 views
Choosing a transistor and resistor for PIC input pin protection from Car Power
Further to my previous question,
Using a PIC to perform switch on and timed shutdowns in automotive environment
I've been pointed at zener diodes and voltage dividers, but I'm now confused by the ...
6
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1answer
484 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 ...
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1answer
131 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). ...
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4answers
231 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
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2answers
97 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 ...
6
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2answers
129 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 ...
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1answer
235 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)
...
3
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2answers
671 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:
...
5
votes
3answers
1k 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
214 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 ...
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1answer
245 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
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2answers
342 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
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1answer
241 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 ...
4
votes
3answers
346 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 ...
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3answers
485 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 ...
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1answer
208 views
Ripple factor detection and measurement
How to measure ripple factor automatically for a pulsating dc output(0-300 v)?
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2answers
254 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 ...
6
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4answers
1k 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
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2answers
174 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 ...
