# 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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### 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 ...
249 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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### 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 ...
147 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?
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### 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 ...
759 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 ...
161 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 ...
205 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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### 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 ...
1k 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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### 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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### 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 ...
171 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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### 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, ...
189 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. ...
299 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 ...
562 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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### Voltage divider ambiguity

considering the following circuit : ...
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### 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 ...
707 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 ...
152 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). ...
264 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 ...
104 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 ...
148 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 ...
280 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) ...
1k 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: ...
3k 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 ...
237 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 ...
281 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 ...
410 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 ...
272 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 ...
415 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 ...
600 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 ...
276 views

### Ripple factor detection and measurement

How to measure ripple factor automatically for a pulsating dc output(0-300 v)?
354 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 ...
2k 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 ...
193 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 ...
1k 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 ...
2k views

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 ...
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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 ...
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### 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 ...
352 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 + ...
374 views

### Whats up with my photoresistors! (Wonky readings, non-stable, I'm missing something)

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 digitalWrite(pin,HIGH) command and ...
1k 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 ...
10k views

### 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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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 ...
232 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 ...
2k 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 ...