The voltage-measurement tag has no wiki summary.
4
votes
2answers
115 views
subtract two AC voltages with instrumentation amps
I'm implementing the so-called "3 omega technique", where a thin metal line is excited with a sine current. The metal has a high TCR which causes a 3rd harmonic oscillation, and I need to measure the ...
0
votes
0answers
47 views
adjustable battery indicator
I've got a simple circuit powered by one 18650 LIon battery.
Now i want to light up a LED when the battery voltage drops under a specified value (e.g. 3,4V)
I know it would be easy with a ...
1
vote
3answers
85 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 ...
3
votes
2answers
131 views
ADC for measuring 0-5V but connected to 3.3V device
I have a BeagleBone (BB) and want to connect the analog output of a motor controller to it. The motor controller creates an output in the range of -4V to +4V and the BB anlog inputs only accept ...
2
votes
3answers
143 views
How do I calculate the input voltage based on an ADC reading?
+UB is a 12V power supply. I have to find the voltage on U_KL30.
I take this U_KL30 as an input at PortA<1> of my MC9S08DZ60 and use an ADC to get a ...
2
votes
5answers
108 views
Flow of current in a simple inverting amplifier circuit
I am considering a simple circuit like the one below. Let us say that the voltage source suddenly turns on (from 0V to 1V), then current will through through the resistor R1, correct? But assuming ...
2
votes
1answer
169 views
Why does my PSU die everytime I test with multimeter
I've set up my PSU to use as a "lab power supply", I'm trying to obtain 12 Volts at 14 amps. I have the red, orange, yellow, black wires separated, and connected the green wire to ground to keep the ...
-1
votes
1answer
71 views
Battery Monitoring IC for 24V 480Ahr SLA
I'm building a battery monitoring system for a large automotive application. Is there any IC tuned to measure a Lead-Acid battery pack's voltage, current and state of charge? The closest I got was ...
1
vote
1answer
93 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 ...
1
vote
3answers
92 views
Embedded system-current draw logging
I have an embedded application that wakes up every 15 minutes and performs some specific function for a period of two minutes.
I need to log the current consumption of this specific function on the ...
1
vote
0answers
84 views
Need help with generating a bi-phasic current
I'm trying to generate a symmetric biphasic current pulse using a Grass S88 Stimulator.
Here's a diagram:
SG is a signal generator with two outputs, S1 and S2, which are generating a periodic ...
0
votes
2answers
323 views
Measuring external voltage on Arduino
I have a Logitech Steering wheel which I would like to interface to an Arduino whilst using it on a Playstation. My aim in the have the inputs from the gas and brake pedals light up a bar graph to ...
1
vote
1answer
236 views
Lipo battery monitor for 1s-6s packs
I want to be able to output lipo battery voltage to a display the remaining juice in the battery much like a fuel gauge. It has to work for 1s to 6s batteries and it would be ideal to work using an ...
2
votes
1answer
838 views
Measure 12V 35Ah battery level in arduino
I am building an arduino device controlling a solar power system. I am a beginner and would like to know what kind of part I would need to connect to the board to acheive this.
-2
votes
1answer
164 views
How can I build a voltmeter / logger? [closed]
I want to build a device whose primary function is a voltmeter without a display. Instead of having a display I want it to interface with a smart phone via bluetooth to read the voltage. Optionally I ...
2
votes
2answers
121 views
AA cell for low power embedded system -Debugging help needed
I am using AA LI cells for an embedded system project.This is a low power embedded project with various modules consuming current in pulses.
Recently one of the prototype board stopped working. ...
4
votes
2answers
225 views
Floating voltage measurements
Is there a very cheap way to measure several voltage differences of 0.1V to 10V (to ~1% accuracy at 10Hz, say), where each pair of measurement terminals may be tens of volts away from the ground of ...
-1
votes
1answer
52 views
Wrong voltage sent to output
Using miniLab1008, I am trying to send 10V to my D/A OUT0 but it sends only 5V and when I send 5V, I get 2.5V. I am using the universal library example VOut01.c
Is this a board problem? However using ...
1
vote
1answer
536 views
Measuring Arduino internal voltage reference with respect to Vcc
How do I read the internal reference voltages of the Arduino (Ardino Mega, ATmega2560, specifically the 2.56v reference) with respect to the input voltage?
I'm trying to measure the remaining battery ...
4
votes
2answers
508 views
How can I measure battery voltage with my MCU?
I am currently using the PIC24FJ128GA010 and I am planning to use Input/Output port to connect my 4.2 V LiPo battery and to check if the voltage value doesn't go below 3.7 V.
I am thinking to ...
2
votes
1answer
198 views
Trying to understand prescaling voltage for ADC with least error
I'm teaching myself EE while designing a 12V DC battery monitor. I'm using a pair of Hall-effect sensors to track charge & load current and looking for the best way to measure the voltage. [An ...
1
vote
2answers
274 views
How can I convert the current from a fan to the microphone headset input on an iphone?
I am working on creating an anemometer (or wind meter) for the iPhone. I am a programmer and know exactly how I could do this on the software side of things, but I am a complete noob when it comes to ...
6
votes
2answers
435 views
Arduino has an input value in disconnected pin
I'm new to arduino. Maybe is an elemental question...
If I load this program:
...
-3
votes
1answer
146 views
Delta Sigma ADC
I need to measure an magnitude of an AC signal with a constant frequency. The problem is offset of the AC signal varies. What I am thinking is filtering the signal and than using Delta Sigma ADC to ...
4
votes
1answer
847 views
Switching a 3 phase pump using a solid state relay
I made a remote (GSM) controlled module for a 3 phase pump close to my friends house. The pump should run at night, and walking the 1km to the switch while they are sleeping is the problem.
The ...
2
votes
2answers
371 views
XBee and PIR sensor
I've ordered XBee wireless transceiver and PIR (motion, here is link) sensor.
When I enable DIO0 digital input port on XBee with "ATD0 3" command it becomes high. I measure it with volmeter and get ...
0
votes
1answer
153 views
Good digital multimeter [closed]
I need a good multimeter which measures volts, amps, resistance, capacitance and inductance. Does anybody know where I can get one? Also, I have one with milliamps, but can only measure up to 200 ...
1
vote
2answers
150 views
Simple Voltage Calculation
Could you please help me about calculating the voltage on the 100 ohm resistor. I know the result is 0.708 V but how could I calculate it, is there an easy way for that?.
3
votes
3answers
203 views
Sensing signal on a power line from high side
I have a circuit design as above. I'm trying to sense the voltage difference accross the \$ 0.1 \Omega \$ resistor. I physically connected the sensory circuit to the low side of the AC line, and saw ...
2
votes
4answers
2k views
Wrong multimeter readings measuring 12V lead acid battery
I just got my first multimeter and when I measured a 12V 1.2ah lead-acid battery I get AC 28.8V and DC 13.4V. Is this normal?
In addition I tested an AA 1.5V battery and I got 2.9V (AC setting 200) ...
1
vote
3answers
421 views
LM317 Ground Problems
I have a LM317 setup as a 3.3V regulator. I am getting 12V input from an Agilent Technologies E3631A Variable DC Power Supply. On this same board I also have a LM7805 regulating to 5V. All of my ...
5
votes
3answers
549 views
Instrumentation Amplifier - how to use it correctly
I am trying to perform some measurements based on a special technique used to detect corrosion in rebars of concrete bloc. The idea is to measure the potential difference between an electrode and the ...
3
votes
2answers
246 views
How do I sense sinusoidal voltage/current on a resistor?
I have an experimental circuit like below:
My aim is to measure maximum or effective value the current on the load.
The current sensor is a simple \$ 0.1 \Omega \$, \$5W\$ resistor.
I filtered ...
4
votes
1answer
7k views
What is the voltage range of a standard headphone jack from a phone?
I want to connect the output from the audio jack of an iPhone to an Arduino.
What voltage range can I expect to see on the audio lines from the iPhone? I assume that turning the volume up on the ...
1
vote
1answer
234 views
What' the low voltage displayed by a voltmeter when only one of its probes is connected?
Recently I was toying with a digital multimeter and observed the following. The multimeter was set to measuring AC voltage with the upper limit of 750 volts. It has two probes which I will call "red" ...
1
vote
1answer
417 views
How can i measure voltages on each phases of a 3 phase system, Using a microcontoller?
How can i measure voltages on each phases of a 3 phase system. The measurement is to be processed by a microcontroller.
Is there any special chips available, or do i need to use the ordinary ...
3
votes
1answer
322 views
What is the difference between a crest reading volt meter and a peak reading volt meter?
We are measuring pulse DC voltage up to 35K on Tinker & Rasor high voltage holiday meters for checking the thickness of coating applications.
I would like to check our units each time they go ...
3
votes
3answers
161 views
wirewound adjustable resistor. Something I missed?
I am by no means an expert on electronics, but I thought that I had a fairly good grasp of the basics. That is, until 10 minutes ago.
1 picture ~ 1000 words, so here is what I have:
The yellow wire ...
3
votes
1answer
230 views
AC Power measureless using MCU, calculations problems
I'm done from the hardware design sensing the current & the voltage levels using my MCU (AVR) & some circuitry
Beside I wrote the firmware to handle the ADC data & so on
But I'm, ...
2
votes
3answers
1k views
Measuring a soundcard output voltage
I have been experimenting with a Soundcard Oscilloscope and I am having some problems understanding what's going on! I have attached a screenshot of my digital scope setup. My hardware setup is ...
3
votes
3answers
5k views
AC current sensor
What would be a simple circuit to monitor a 120 volt line current?
Connecting an Arduino to the circuit would allow one to detect when the attached device has shut down, for example a washer, dryer; ...
3
votes
2answers
2k views
How does a voltmeter work?
Let's say I've got a circuit with a two-pole Thévenin equivalent that has DC voltage difference U and out-resistance Ro. What does the voltmeter do? I suppose it has an internal, very large resistance ...
1
vote
2answers
1k views
When measuring AC via an ADC, is it bad to have common ground?
I've got a circuit that looks like this:
My input is low voltage AC at low current and I want to measure this with an ADC at 3.3V (eventually, haven't got there yet).
Is this safe/correct? It ...
3
votes
2answers
181 views
How stable are digital multimeters' parameters?
I live in a region where standard mains voltage is 220 volts. Recently I tried to measure it using a digital multimeter. The multimeter specs say that it has maximum error of 1,2 percent of the ...
1
vote
1answer
101 views
What is the best way to remove the non-rejected portion of a common-mode voltage and any bias voltages from a differential voltage measurement?
I am using a high-common mode differential amplifier (AD629) to measure several DC 10 to 15 voltages stacked together. Since the AD629 is not the cheapest amplifier in the world (though not as ...
2
votes
2answers
1k views
How to convert voltage into digital signals?
How do I convert voltage into digital signals or pulses? For some reason I have to get voltage readings of the battery connected to the UPS of the computer systems.
For that purpose I am designing a ...
1
vote
1answer
138 views
Voltage/current conversion
I have a device which uses 4.5 watts @ 18V (0.245A). The device can be powered by 12 volts, which I plan to do so.
I can I work out the current draw at 12 volts based off the above info?
4
votes
3answers
696 views
Basic 741 Op Amp Question
I am trying to build a basic 2 input summing amplifier using radio shacks 741 op amp. I have a feeling I damaged my IC chip through my wacky experimentation's. But lets run through the math just in ...
1
vote
3answers
470 views
Measuring voltage across a resistor using a micro controller
I want to measure voltage across a resistor using the ADC of a PIC micro controller. But my problem is that both ends of the resistor are above GND and may be above 5V. But the difference is always ...
3
votes
2answers
1k views
Can I Test Bug Zapper's Voltage With Multimeter?
I have The Executioner bug zapper:
Although it uses 2 AA 1.5v batteries, it also has voltage multiplier like Cockcroft–Walton generator i guess and would like to know if it is safe and would make ...
