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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how to calculate C for lm7809?

I need to use a LM7809 to reduce 12-14V to 9V , the device is using 40mA at normal state when I search google for application circuit - I got all kind of valus for Cin , Cout. use this datasheet ...
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How do I create a portable, battery-powered relay that switches in the daytime?

I have been trying to make a (hopefully very simple) circuit for this that just uses a couple resistors, diodes, and transistors that can fit on a small breadboard and be powered by a 9V battery. ...
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Project help, need a way to allow voltage flow only if certain limit

Not sure exactly how to word this but I'll give it a shot. In my project a detector will output anything from 16uV to 750mV. To succusfully trigger a Time-to-Digital converter the voltage around the ...
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Is there a difference between these two circuits?

I might not have drawn the second one right, but imagine if it was a live wire in a bathtub going through the water and the plumbing to ground instead of returning to neutral, except way more volts. ...
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Question of possible circuit

Suppose we have an alternating signal and another signal is produced in the loop which is DC. Is there a circuit which tracks down the DC signal even if it is mixed with an AC signal?(somehow removes ...
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Determining current through LED light

Not an electrical expert so please bear with me. I bought a no-name brand LED lamp that I would like to use with my 9V DC adapter as power source. The lamp uses 3 AA batteries in series. Batteries ...
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For a step down converter for 1100W appliance is a linear or SMPS transformer required [closed]

I have bought a Joule sous vide immersion circulator from USA. Want to use device in India. I need to convert AC, 240V 50Hz to 110V 60Hz. After reading the literature on the company's website it ...
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Why do these two nodes in these two circuits have different values?

In the second circuit, the diode and the resistor are in parallel, so why is the voltage at Vbq is Vr5q-Vbeq but not like the first circuit the voltage gets divided by the parallel resistance?
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finding voltage peak to peak using v(t)

My formula is v(t)=10cos(30pit). My theory is that Vmax is the 10 which means Vpp is 10V and -10V. Since the formula for v(t) = vmcos(w*t+theta)
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What's ground? Is it the point defined as 0 V of potential or voltage? If the latter, is it because we measure its voltage with respect to itself?

I have some questions regarding the definition of ground that some people use. One question leads to the other so I've organized them below. Some people say that "ground is the point/node defined ...
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Constant current limiting circuit

Can someone help me understand the working of this circuit: My questions : Please explain me how this circuit will work in its entire operation range. I am not able to understand the purpose of the ...
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Constant current LED driver using transistors

I have this circuit: I understood the operation: On power-up Q1 and Q2 are off. There is no collector current so L1 is off. If the digital control input on the left is brought high (5 V) Q1 will ...
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Can I increase DC voltage using capactiors in series and then use a voltage regulator?

I am (re)learning electronics and I am currently playing around with "simple circuit" to practice a bit. For testing, I am doing a simple circuit that could have 2 different input voltage (...
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cjmcu-3221 i2c problem - doesn't show on search

I have big problem and strange problem with the device, I have connected it into Arduino VS - 3.3V GND - GND SCL - A5 SDA - A4 didn't connect anything to ch1-3 ...
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Control voltage to heat resistor using PID

I have a question about PIDs. I have a 2.2 kW heat resistor powered from 220 Vac. I would like to control the resistor using PID. As I can see the most PID based control systems are using a Solid ...
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37 views

Buck converter input voltage lower than the designed output voltage

I have this buck converter which is designed to produce an output voltage of 9V for an input range of 18V-36V. The datasheet of the buck converter mentions that the minimum required input voltage is 4....
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1200W, voltage and cycle converter 220 to110

I have bought a Joule sous vide immersion circulator from USA. I want to use the device in India. I need to convert AC, 240V 50Hz to 110V 60Hz. After reading the literature on the company's website ...
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Solar Panel Simulation Circuit working, LT-SPICE

I am here again with the same circuit but this time with no errors thankfully. circuit is working but i can not understand the working of circuit. I am not getting why in the single cell's schematic , ...
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Do electrons go towards higher voltage or lower voltage?

Can someone clear this up for me once and for all? I feel like Thomas Edison really screwed me when he made everyone believe that current is movement of positive charges. Do electrons go from high ...
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Do different Line-Ground voltages on a 240v L-L PSU fed from a 3 Phase High Leg Delta system pose a problem?

I'd like to know if there are any negatives related to powering an ASIC miner PSU at 240V, 2 hots and a ground (C13 plug), from a three phase, center-tapped, high-leg delta system, when the line to ...
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55 views

Can someone please explain how to add an external potentiometer to a voltage regulator with a trim pot?

I'm building an LED light panel and I'm setting up the electronics according to this video. As you can see, he uses a 22K potentiometer and a 6.8K resistor. I would like to understand why he uses ...
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1answer
47 views

Amplifying tuned receiver

I have been trying to amplify the output of this near field LC receiver with different OP AMP types and configurations. All the circuits I've tried have either had a really high offset at the output, ...
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1answer
56 views

Voltage is 0.05 when switch is closed

I am new to electronics. Iam designing a simple circuit where I have to make a digital switch: Here is what I have designed in Proteus: There are 2 issues: I want it to output 5V when I close the ...
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Wiring a siren to an alarm system, siren isn't going off when the alarm is triggerd

Hello I have an alarm system of Jablotron Oasis 80. I want to hard wire a sirene of another brand to it Aritech S290. When the alarm goes off then the beacon of the siren is flashing, but there is no ...
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How is the effective parallel resistance of this resistor network determined?

I have this circuit: The effective resistance at the reference node of D4801 is given as Rb = R4802||(R4805+(R4807||(R4806+R4808+44KOhm))) = 9.129KOhm I am not able to understand how this formula is ...
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102 views

Working of the below Op-amp circuit

I have seen this circuit at my workplace and I'm trying to understand the working and the purpose of each component in the below schematic. I also happen to note that this was a constant current ...
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76 views

Why is there a LC filter in front of the DC/DC converter?

I have to study this circuit. I understand that Graetz's bridge is there to convert the current to positive, but why is there a LC filter at the entrance of the converter?
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frequency of MCP3008

I built BOOST CONVERTER, I sample the output voltage with A/D and control it using RASPBERRY Pi3, I set the switching frequency of the BOOST CONVERTER 70KHz, and the frequency of the MCP3008 1.35MHz, ...
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432 views

Why is resistor needed in ADC circuit

This figure shows an ADC. My question: Why there is resistor (R) connecting to inverting pin of each OPAMP. Are they really necessary? In my opinion, they can be removed because you will have to ...
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DC/DC MC34063 serial boost converter for increasing voltage

I am trying to build one ultrasonic mist IOT device for this github project. SO in the power supply part it needs to have almost 70V input voltage, so for more Voltage you can use boost converter ...
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My usb ports outputs different voltages

I have made circuit that runs on USB. however, when i plugged into front panel of my pc or raspberry pi, it only gets around 3.3v, but when i plugged it into back of my pc, it gets 5v as intended. ...
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Behavioural Voltage

If I directly connect it to the power stages in a midstage model from an output of a rectifier, the rectification seems off. If I add it to the power stage using a Behavioural Voltage, it seems smooth ...
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Turn on LED if certain voltage range is detected

I'm new to circuits and in a side project I'm trying to design a DC circuit without microcontrollers that will turn on an LED if a certain voltage range is detected. For example the LED turns on if ...
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58 views

Ceiling fan voltage

I bought a ceiling fan, and ordered one rated for 110 volts. When it arrived, the fan motor housing was marked 220 volts. I told the seller they'd shipped me the wrong unit, and I'm being told (in ...
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1answer
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Circuit transform

Given circuit (a), and I want to find V_out as a function of V_in. R1, R2, V_B is constant. Since V_out = I*R_2, I need to find the current flowing int the circuit(a). Is it OK to change the circuit(a)...
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Why are cables rated for current not power?

I was wondering, since resistors are rated for power, not current (so one can blow them with both overcurrent or overvoltage), then why are cables rated only for current? Aren't resistors just stacked ...
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1answer
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HP C8941 Photosensor operating voltage and circuit

I have at my disposal a photosensor (Optical encoder) with "C8941-80018", it has three cables: Black, Green, and Blue. I want to know the Operating voltage for this optical encoder and a ...
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1answer
46 views

Gain with load or gain without load?

There is a problem I have been dealing with for hours. In my Electronic 1 lecture, small signal analysis was like this: The small signal equivalent of this circuit in my lecture notes was this: When ...
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1answer
54 views

Can this be simplified even further?

Wondering if this could be simplified even further. Feels like I can do more with the 1000 ohm and the 2000 ohm resistors on the righthand side.
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LT-spice-Simulation model for PV panel

I am totally new to LT-spice and i want to simulate a model for PV panel. i followed a youtube video as itas, but my circuit is not working. i have no idea about the errors it's showing. please help. ...
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Mechanical Relay “Must Operate/Release Voltage” - Confusion Around Terminology

I have a relay and am confused by its operation. It is a Potter & Brumfield Relay, model R50-E2-X1-24V Datasheet: https://www.westfloridacomponents.com/mm5/...
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58 views

Is there anything I can do to simplify this even further?

I feel like there is something more I can do, especially with the current source. The voltage in the voltage source is 4.024 V, and the resistor is 2556 ohms.
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Voltage measurement is different between an oscilloscope and a multimeter

I am trying to measure the voltage between 2 points using an oscilloscope and a multimeter. Question 1: I am getting a difference when I measure the voltage using an oscilloscope and using a ...
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47 views

Confusion in peak detector circuit

When we apply a sinusoidal voltage source as input to a peak detector circuit (assuming capacitor is initially discharge and ideal diode and ideal voltage source), the diode becomes in forward biased ...
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47 views

voltage drop help

I have a little 24Vdc circuit where I am powering a small DC motor thru a set of contacts (connects the negative) on a relay where I then latch it in after the momentary switch controlling the relay ...
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Why does my lightbar draw more current when connected to a battery than a power supply

When I measure the current draw of the lights when connected to a car battery, they draw about 2.4A However if I connect the lights to a 12V power supply, they only draw around 0.8A. Even though the ...
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Voltages decreasing while using the 6 and half multimeter

I am using this this desktop Multimeter - 6 and half multimeter Whenever I measure a voltage or current in the auto mode, the last three digits continues to decrease and keeps on decreasing till the ...
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1answer
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Why is the sum of resistances different?

For the following circuit, I found the total resistance with the following equation: However, the solution calculated the resistances in the left and right portion of the circuit in summation with ...
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Need help finding flaw in the voltage regulator circuit

I made a discrete voltage regulator circuit and constructed it. There input comes from a bridge rectifier fed by a 15V 10A transformer. The output current is limited to 3.3 Amperes. Why is that, how ...
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62 views

Charging Lead Acid battery using SMPS - unexpected voltage measured at battery

I am trying to charge a discharged 12 V Car Lead Acid Battery using a SMPS. According to voltage information provided for charging lead acid battery (https://batteryuniversity.com/learn/article/...

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