Questions tagged [voltage]

Voltage, otherwise known as electrical potential difference (denoted ∆V and measured in volts) is the difference in electric potential between two points (adapted from Wikipedia). Voltage can be constant (DC) or varying (AC).

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Hysteresis measurement voltage behaviour

I am currently doing a hysteresis measurement using the below depicted measurement setup, however with different values. The odd thing is that I have different VM2 values, depending on how I connect +...
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Why are the Pololu AVR programmer and Microchip Studio showing different target voltages with the same PCB?

Yesterday I programmed a PCB (powering it using an external power supply, it's a PCB of a commercial device) with an ATMEGA2560 MCU using the Pololu AVR v2.1 programmer and the Microchip Studio ...
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What's the relation between SWG, input & output VA, cross sectional area, number of turns of an isolation transformer?

I made 3-4 transformers before and learnt a lot about transformers, I didn't have a formula so I was following heuristic approach to resort to the right SWG and right number of turns, however this ...
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Power line switches from 5 V to 3 V when I change the device

I have created the circuit board below; in principle, it works. I press a button, the corresponding "M"-port (M1, M2, M3) closes to ground and a test LED lights up - also current flows ...
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Working of this protection circuit battery

I'm going through this application note - because it is said that the MCP73833 device does not allow to charge the battery and drive the load simultaneously. Hence, they've given the below circuit in ...
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Understanding the function of Boost capacitor

I'm going through this MOSFET Driver IC - MIC5021. Since this is a high side switch, the gate voltage should be higher than the source voltage, which would be the Source voltage, Vdd. According to the ...
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Question regarding MOSFET driver

I'm going through the datasheet of this MOSFET driver IC - MIC5021 to understand the pins and the terms better. In the first page, it is mentioned as, The MIC5021 high-side MOSFET driver is designed ...
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8-channel logic level shifter: how to get 3.3 V output voltage?

When I apply 4.8 V (Arduino 5 V) to the B side of my level shifter TXB0108, I always get 1.2 V (which is the minimum) on the A side. Is it possible to get something like 3.3 V or at least 1.8 V (it's ...
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Can I use a 3.3 V / 5 V level shifter to convert between 5 V and 12 V?

I need to interface few Arduino GPIOs to a 12 V device. The direction of GPIOs is not fixed and can be programmed using a different set of control pins, so I need a bi-directional level shifter. Is it ...
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Question on Battery Charger

I need a Lithium ion battery for a project. In many places, I have searched and there seem to be 2 different voltages for the Li-ion battery. One is 3.7V and one is 4.2V. In someplaces, it is said ...
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What is the name of this specific method used to solve for the step response of a circuit?

I'm entering the third year of a degree in Electrical Engineering and we're just now getting to the step/transient response of circuits. My professor is enamored with a particular method for solving ...
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RTD - convert measured voltage to temperature

I have a 3-wire RTD connected to a Wheatstone bridge and then to a INA. The Vout from the INA is then connected to a ADC. How can I convert the measured voltage from the ADC to the respective ...
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Bridge rectifier speed

I pulled an old computer power supply apart and salvaged a bunch of parts. One of them is a GBU806 bridge rectifier. Wanting to learn about these things and play with my new toys, I hooked up a signal ...
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Understanding battery charger terminology

I've a few questions regarding this charge management controller IC. On page 11, section 3.0, they mention Charge Status Outputs (STAT1, STAT2) and Timer Enable and in section 4.3, page 14, they ...
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Is P90NF03L 3.3V logic level MOSFET?

So I want to control my 12V (up to 10A) load through a 3.3V logic level MOSFET. I have purchased the P90NF03L MOSFET but I don't trust my datasheet reading skills so could someone please confirm that ...
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Can ESP32 node MCU read 5V input?

So I've got a YFS201 sensor which I was using with a Arduino Nano. Now I am employing a ESP32 Node MCU which uses 3.3V logic. I'll be powering the ESP32 with 5V through the Vin pin. I'll be powering ...
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How to find the input injection current of this device? [duplicate]

In this device, no information is given regarding the maximum input injection current. How to find the maximum input injection current from this datasheet? I'd like to know the current for the device'...
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Does the orientation of the Ethernet magnetics matter?

I've this Ethernet magnetics transformer connected between the PHY and the Connector? Does the orientation of the magnetics with respect to the PHY matter? Meaning, should the common mode choke inside ...
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Reading voltage on flyback diode's anode

So I have this motor driver that I've already asked a couple dozen questions about that I have finally got around to building. Here's the final schematic that I'm using: It uses only N channel ...
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Forward voltage of LED

Somehow LEDs with a lower forward voltage than the source with a 100 Ω resistor tend to blow up every time the switch is turned on. How can I understand forward voltage better?
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Protection current

How to find the maximum injection current that the internal (clamping) diode can withstand? It is not mentioned in this datasheet
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ESD problem and how to solve

We have a problem with contact discharge of 3kV on a housing part. The PCB with the PHY are installed in an aluminum lower part with plastic upper part (dimensions approx. 80x80x80mm). The contact ...
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How does a capacitor double the transformer output?

I recently got a transformer with a ratio of 10/1 and fed 40 VAC into it. I got the ~350 VAC on the secondary which was expected. When I connected a 1000 V, 1 μF AC capacitor to the secondary its ...
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H-bridge - MOSFET driver

I am trying to implement an H-bridge with the MIC5021 for the high side of both legs and an MIC5020 for the low side of both legs. I have used the MIC5020 in other designs and it seems to be working ...
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Appliances from Saudi Arabia in Europe? [closed]

I got my hands on a Xbox Series S on my trip to Saudi Arabia and now that I am going back home I came to a sudden realization that electricity is in a different configuration to the one in my home ...
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Why does this TP4056 module give more than 4.2 V at the output? [closed]

I have two TP4056 modules and the cut-off voltage is too high. It is around 5 V. Why is this happening?
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1 answer
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How do I connect the negative wire to three systems at different voltages?

I have a system with three major components: throttle motor (powered by 48 V battery) steering motor (powered by 12 V battery) Arduino (powered by 12 V battery) The 48 V, 12 V, and 12 V batteries ...
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Can a 125 V, 2 A cable handle 230 V? [closed]

I did not realize and bought a T5 LED grow light tube from the US, and I live in the EU. I now have an issue with how to connect it correctly. I have 8 LED tubes (10 W each - 80 W total), connector ...
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Measuring voltage across a rheostat

I want to measure the voltage across a rheostat. For this purpose I connected a voltmeter in parallel to it, but even on turning on the circuit there was no deflection in the voltmeter whatsoever. ...
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1 answer
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How can an analog multimeter have a combined mV and µA scale?

Looking at analog multimeters on Amazon I came across several that have one switch position that appears combined for the lowest V and µA settings. I've used various analog multimeters over many years ...
2 votes
3 answers
103 views

Can we connect multiple devices to the mains with just 1 cable?

The project: An Arduino DIY Relay-controlled aquarium with a water pump, a heater, and a light bulb. All 3 have the exact same wires according to the EU standards: 1 "hot" brown wire and a ...
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Buck converter output voltage

I'm using this MIC23150-4YMT-TR with fixed output voltage. On the PCB, I tested the output & found that it is 2.6V and not 1.2V. I checked it on 3 PCBs and all show the same result Schematics:
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Did my PWM controller blow my DC motor capacitor?

I'm building a circuit to control the speed of an air compressor motor. Even though the compressor motor is not supposed to run at lower speeds, I've seen itdone without doing much harm. To control ...
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4 answers
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Convert 3.3 V PWM to 5 V PWM

My Raspberry Pi 3b generates a 3.3 V PWM signal, but I need 5 V PWM for my motor driver. Is there any chance to solve this problem?
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4 votes
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How to generate -5 V from +5 V and GND?

I have an Arduino providing +5 V and GND. I have a component that requires +5 V, common GND, and -5 V connections. Is it possible to generate -5 V? If not, what input voltage do I need? I am driving a ...
1 vote
6 answers
468 views

Voltage of AA rechargeable batteries suddenly drops

I am having problems with rechargeable AA Ni-MH batteries. We are using 6 AA Ni-MH rechargeable batteries to power our device, but after about an hour of usage suddenly one of the batteries' voltage ...
11 votes
4 answers
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Is it a problem to use a capacitor at or near its rated DC voltage?

Are there important points to consider in typical or special applications when capacitors operate with applied voltage close to their rated DC voltage? Such as: 15 V on a 16 V-rated capacitor, 24 V ...
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Designing a digital display [duplicate]

I was working on a design question (this is not homework, just personal practice). So I have a temperature sensor with a non-linear response, and ideally I would like to design a digital display ...
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1 answer
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How to find the differential equation of the current i₁?

I am trying to find the differential equation of this circuit: I tried to use KVL at the left mesh which gave me \$E=R\cdot i+V_c\$ From \$V_c\$ I can calculate \$i_1\$, but then I didn't know how to ...
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2 answers
138 views

NPN transistor not emitting anticipated voltage [closed]

I have 12 V connected to the collector of an NPN transistor. I have a pin of an ESP8255 (which emits 3.3 V) connected to the base. I'm trying to power a 7-segment display with it, but the emitter ...
2 votes
3 answers
669 views

What lead of a voltmeter is subtracted from the other to get the voltage?

As far as I understand, voltage is a difference of potential energy between two points, and that current flows from the negative to the positive pole of a battery in a circuit. Thus, according to ...
2 votes
2 answers
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How can one vary the resistance of a circuit using a microcontroller? [closed]

I am trying to have a microcontroller light up a few LED's, all LED's have a forward voltage of about 3V. The issue is that my power supply(which in this mock-up is 9V) will push too much voltage if ...
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1 answer
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Three-phase, 480 V, 200 A supply, 480 V, 30 A load/charger compatible? [closed]

I have a 480 V, 30 A charger for a large JLG/lift. The power cord for the unit says it is only rated for 30 A. Could I still use this unit with my 480 V, 200 A source/disconnect? Would I need a ...
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1 vote
1 answer
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How to power an embedded board using capacitors and solar panels?

I am working on a battery-less system. The system has the following energy pipeline: Solar panels -> DC-DC boost converter -> capacitor -> microcontroller. Here the solar energy is harvested ...
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2 answers
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Maintaining voltage on PCB track

Suppose there is a really long track (not infinite) running over a 2-layer PCB with the bottom plane being the ground plane (just to complete the reverse path of the current). Now, on one end, 5V is ...
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4 answers
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Why does a smaller capacitance equate to a larger voltage drop physically?

I was hoping someone could explain practically/physically why a smaller capacitance has a larger voltage drop than a higher capacitance. The equation is V=Q/C, so based on that it's very easy to see, ...
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Analog multimeter reading DC voltage unprecisely

How do we fix and/or calibrate an analog multimeter reading DC voltage rather inaccurately? 24 V is read 26 V 12 V is read 13 V 1.25 V is read 1.5 V It worked normally three years ago. It was left ...
2 votes
2 answers
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Lithium-ion batteries lose capacity over their lifetime, but what about 100% voltage?

Over the lifetime of a Lithium-ion battery (charge cycles), does the maximum voltage that the battery can be charged to decrease, or does it remain the same, and only the capacitance decreases (...
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Can this work as a dark-activated light circuit?

I am fairly new to electronics and have been tasked with the question of describing the behaviour of this circuit. I can see that the LED is supposed to switch on when it is dark, but I am struggling ...
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Is someone able to explain this potential divider circuit in detail?

This schematic is part of a practical that we will later solder on to a PCB. It is a potential divider, but I have never seen one like this. There are multiple test points on the circuit to measure ...

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