# Tagged Questions

Act of measuring voltage

56 views

### safe way to reduce 200V to ~20 volts?

I am totally clueless when it comes to circuitry, but am trying to build a grid charger for my old hybrid car, using an online DIY write-up. This charges the battery at a constant current (350-600ma ...
58 views

### Can I guess 5/3-wire RS-232 pins from voltages?

Objective: interface to an HPLC pump via the RS-232 interface described in the manual. Communication protocol is well described. Pinout is not described at all. Can I guess the pinout based on ...
48 views

### If I connected a voltimeter between a galvanically insulated phase and ground, what voltage value would it show?

I got asked that question and got me to doubt. If I had two phases L1 and L2 and N, all galvanically isolated using an isolation transformer, and I were to measure L1 vs ground, what voltage would the ...
33 views

### Thesis Theoretical Section [closed]

I am starting my bsc thesis preparation (hope I am saying it right) and I am wondering what should I include on the theoretical part. MY main experimental subject was the examination of the voltage ...
38 views

### Will massage electrodes work for eeg?

Have anyone tried to use massage electrodes for eeg? I believe as they conduct high charges probably using inexpensive metals they are not suitable for measuring tiny voltage changes but I'm not sure.
155 views

### led circuit - a challenge of designing a circuit with 192 LEDs in

I have been faced with a challenge of designing the circuitry for an LED light. This light will have 96 LEDs in Cyan with a max Vf of 3.7V and another 96 LEDs in red with a Vf of 2.6V. There is to ...
57 views

### Check if an analog voltage is 0 [duplicate]

Is is possible to check if an analog voltage is zero (or very close)? If it helps, the input to this circuit will be the output this differential amplifier:
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### How to measure the voltage drop between 2 points separated by a long distance?

In the project I am working on today, I need to measure the voltage drop between a portable probe and a fixed reference. The big challenge is these 2 elements could be distant from each other of up to ...
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### What are all the reasons that transformers are considered safer? [duplicate]

I am making a circuit for measuring AC mains voltage and current and I want to avoid using a transformer because it introduces distortions. But everyone says that the circuit will be considered unsafe ...
118 views

### AC voltage measurement with a microcontroller

I want to build a circuit that will eventually calculate power, power factor and thd for a light switch or a wall outlet. But I'm having some problems with the voltage measurement circuit. ...
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### Converting Watlow 0-24V controller output to 0-10V for a NI fieldpoint data acq

In order to record the temperature in a vacuum chamber, I have a watlow PM9C1FA-AAAAAAA that outputs a 0-24V signal from a type K thermocouple. The data acquisition system that it is connected to is ...
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### How to use supply voltage for a small circuit from a huge variable power supply?

I have a 300 watt solar panel whose voltage and current need to be monitored by installing a device there. There is no source of power supply that I can use for this monitoring device but the solar ...
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### Significance of Negative reference voltage in DAC0808 Chip

In DAC0808, positive reference voltage is used to set the maximum output current through that chip and the value of the output current can be changed by appropriately setting the bits. Normally, in ...
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### Using an arduino to read a 5050 LED signal

I have a project right now where I have access to a header to control standard 12v 5050 LED strips. What I'm trying to do is read that signal with an Arduino, and then use the values to control other ...
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### Effect of Positive and Negative voltage supply in LM741 opamp

At first,i created a simple schematic of non-inverting amplifier using LM741 having a gain of 2. The supplied a.c voltage at non-inverting input is 1V having frequency of 50 Hz. And i get the result ...
187 views

### Measure high voltages with a multimeter

My multimeter is rated to 600V. How can I readily (and safely) use it to measure higher voltages?
117 views

### Using op amp to measure battery voltage

I have a question regarding the usage of op amp to measure battery voltage. I know there are battery gauge IC's dedicated for that, but I'm trying to do this to both understand the op amps better and ...
18 views

### Signal offset using FRDM-KL25Z

I am developing a voltmeter using FRDM-KL25Z and I needed a voltage divider with a 1.65V offset, and here is the circuit I am using: Does the offset work well? Is there any other (easy) way to do ...
280 views

### The potentiometer used in electronics is not a measuring instrument. Why it is called a meter?

Why this kind of variable resistor is called a "meter", when it is not a measuring instrument? I have seen another instrument of same name. In our school physics lab, there was a big rectangular, ...
121 views

### How to combine LED and voltage divider

I want to detect the presence of a 8.4V voltage source from an Arduino, so I'm using a voltage divider to step it down to a voltage safe for the Arduino to read with an digital pin. However, for when ...
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So i got a multimeter from a friend for free. This is the one: Multimeter Info In the manual of the multimeter it says that the lowest resolution of DC Voltage is 0.1 mV. does that mean that i can ...
65 views

### Multiple voltage measurement

I have to measure voltage for about 100 different channels in one object and the problems is space for equipment (100 transducers would require lots of space) and price of transducers. Is there a way ...
47 views

### If there's no current through a battery, can it supply a voltage drop across a resistor?

simulate this circuit – Schematic created using CircuitLab I've solved for all of the currents in the circuit (I used an equivalent resistance for the middle two resistors) and the current ...
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### How do I calculate voltage using the complete diode method?

Doing extra examples for a electronics class, came across a section uses the Complete Diode Model (We haven't covered it in class in much detail, only the definition). The question is: Determine the ...
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### What happens if I put my DC voltage source AFTER the diode instead of before?

I have a homework question on diodes, in which I have to calculate the Voltages across the diodes. All the questions I have encountered thus far have had the DC source BEFORE the diode. This one has ...
109 views

### ADC for low signal (microvolts)

I am a newbie to electronics I have a sensor that can provide a range of [400 microvolts - 5 Volts] I want to transform this signal into Digital so that i can read it on computer, I'm seeking a ...
81 views

### How can I calibrate my sound card based oscilloscope?

I'm using Soundcard Oscilloscope software that presents as below You'll notice that the display has a grid, and in the example is set for 100mV/div. Since it's using the sound card integral to my ...
61 views

### For sensing continuous Voltage and deamplifier circuit? [closed]

Basically, OpAmp is used for the purpose of the amplifying the voltage in the circuit and in the circuit below, i supplied 10v and it is deamplified to 1A. The ratio of attenuation is 0.1. The circuit ...
58 views

### Measuring battery voltage fluctuations and spikes in an analog wall mounted clock when the second hand ticks

As the title suggests, my goal is to be able to pickup minute voltage fluctuations of an AA battery cell of the wall-mounted clock, each time the second hand ticks. My first intuition would be to ac-...
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### Is it practical to measure an unknown capacitance by measuring its impedance?

I've recently seen some fourth year engineering projects at my school (University of Waterloo) and one that I found interesting was this novel pressure sensor that uses nano silver separated by a di-...
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### Ungenerated Voltage across the DMM and random spikes across the Oscilloscope

I am working with piezoelectric material known as PZT-P-43 MY PZT datasheet (please look at the red outlined). So far I have been trying to find the Energy that is being delivered to my 100uF ...
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### Non-rectified Voltage output across the capacitor

So I am testing my PZT Piezoelectric material's Voltage output across a Capacitor of 1000uF after converting AC to DC using an Oscilloscope. Oscilloscope model: Gwinstek GDS-2102. The diagram is my ...
57 views

### KVL not satisfied during simple diode series

A power diode in the reverse biased position is connected in series to a 2.5Mohm resistor. The voltage source is connected in series to these two components and is set at 10V dc. The voltage across ...
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### Piezoelectric Voltage and current measurement across a 3.3kohm resistor.

I am testing a PZT 43 material with tapping sequence. The measurement of the material is: 10mm in length and 0.8CM in diameter. I am tapping the material with a plastic and holding it down with a ...
51 views

### Efficiently sense volage DC/AC?

In our current design we are sensing 50 Vdc input voltage through a microcontroller by using resistor divider network, caps for filtering high frequency noises,diodes for protection. The problem here ...
282 views

### Voltmeter measuring electromotive force of a battery

It is known that connecting a voltmeter directly to the terminals(without any other load) of a battery will show you the value of the battery's EMF.However,I don't really undrerstand how this happens....
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### Voltage level when connectiong two power sources [closed]

I've experienced the following situation the other day. When connected to this smart powers charger (never seen one of those), the battery voltage dropped. Made me wonder about two questions. 1. ...
5k views

### Multimeter exploded during ACV measurment - What did I do wrong?

simulate this circuit – Schematic created using CircuitLab A DT-830B meter. I bought a new transformer, and I was trying to measure the output voltage. I plugged the probes on 'VΩmA' (not 10 ...
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### Differential measurements with high voltage oscilloscope probes

This interesting post about differential measurements with a scope has raised a few questions in my mind. I have read about true differential scope probes and they seem to be very expensive. Would ...
98 views

### How to measure a BC-547 transistor's details?

I am new in electronics. What I am trying to do is measuring everything of BC-547 transistor's details from a basic circuit design practically. I want to measure as example: collector-emitter voltage,...
117 views

### How does vacuum tube heating (heater voltage) affect tube performance/sound?

I have replaced a 12AX7 tube with ECC85 in my guitar amp. Seems to work great and sound great. The part that is questioning me is whether the sound is being at its best because it takes a good 20-30 ...
60 views

### Battery voltage isolated monitoring on Microcontroller

Is it safe to directly measure high capacity battery (100 Ah to 300 Ah) voltage with Microcontroller's Analog to Digital Converter (ADC)? Would it be enough to use just a simple voltage divider to do ...
197 views

### Battery voltage select and ADC measurement (OpAmp + uC)

I need to measure battery voltage which supplies my electronics. Vbat supplies buck-boost DC/DC converter then goes to uC and other ICs (3,3V). I want to use 3x2 goldpins in conjunction with OpAmp to ...
110 views

### Can I measure if current is on or off in cable with 24v DC (in a cheap way)

I have a number of valves that control the heating in rooms in our house. The valves have a pin on top which opens or closes the valve. The position of the pin is controlled by a regulator that sits ...
51 views

### what is the base temperature when using ppm/c

I am not sure If I have phrased the question right but if not please correct me I want to know when Accuracy Parts per Million mentioned in the datasheet of voltage reference they say for example 5 ...
65 views

### VGA levels, why are they wrong?

I read everywhere on the Internet that voltage levels in the color components of a VGA cable should go from 0 V (dark channel) to 0.7 V (maximum brightness for that channel). However I tried to ...
153 views

### Correct way to measure a wall wart voltage [duplicate]

I got a full drawer of second hand wall warts which I'm planning to use for powering arduino projects (mostly 5V "pro mini" or "nano"). I'm using a voltmeter to check that they are still working, ...
240 views

### Is voltage measurement of a battery done in series?

This might be a stupid question but I can't find an explanation. Voltage measurement is done in parallel. But when we measure the voltage of a stand alone voltage source, say a battery, it looks like ...
113 views

### Measurement of negative DC voltage

I want to measure -30Vdc up to 0Vdc using a microcontroller. I'm basically measuring a voltage source with an output current of upto 2A. I need to bring the voltage up onto a scale of 0V to 5V so ...
62 views

### Measure Voltage (Divide) on a current source

I need to use a constant current source 20mA, the current flows through multiple diodes and resistors which are in series. The resistor value can vary from 0 to 1.6k and also a possibility of Open. ...