Questions tagged [ac]

AC stands for Alternating Current. It usually applies to voltages with >100 V RMS, but can also be used for other AC voltages, like 24 V industrial AC power.

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971 views

How far can an AC signal actually go?

I have the following circuit schematic: simulate this circuit – Schematic created using CircuitLab The systems is a water level control circuit, in which a signal is sent from the water level ...
319 views

How can the diode conduct in negative half cycle of AC signal in clamper circuit?

Could you kindly help me understand the clamper circuit. I watched a couple videos and I'm confused. My confusion is in positive clamper circuit. How can the diode conduct during the negative half ...
23 views

Protection circuit for inverter or generator during blackouts

During blackouts in Ukraine it's a common practice to turn incoming AC voltage switch off and power all in-house power AC lines with an inverter or a gas/diesel generator. Can someone share a ...
72 views

What is the correct formula for the 3 dB frequency of an RC or LC Circuit?

Before we jump to another post where the formula is I am reading through the text book Microelectronic Circuits 8th edition by SEDRA/SMITH. In the text, they show this table. Here it shows the time ...
40 views

3-Phase system Voltage conversion

If we are converting from Y to delta configuration or vice-versa, how do we convert the phases of our voltages? I've seen that we need to add or subtract 30 degrees from one another, but I don't ...
88 views

What is the role for each of these AC coupling components?

I'd like to learn more about the RP2040 PWM Audio AC coupling circuit found in figure 22 in this document. Figure 22. Schematic section showing the Analogue PWM audio circuit Even though I understand ...
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59 views

Non contact AC voltage detector circuit current calculation

This seems to be a common circuit for a non-contact AC voltage detector: Non-Contact AC Line Detector using BC547 The probe generates a small amount of current when it is near an AC line due to ...
1 vote
178 views

How is the reactance of a capacitor formulated?

Question: Understanding the Reactance of a Capacitor Hi everyone, I'm having trouble formulating the reactance in a capacitor and would appreciate some help. Here's what I understand so far: We have ...
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62 views

Contactless AC line detection using a single transistor

I have seen circuits that are used to detect the presence of AC voltage without any contact, like the one below. Non-Contact AC Line Detector using BC547 I have tested this circuit and it works fine. ...
67 views

I'm trying to wire this motor I have, but I'm not sure how to read this diagram

This motor is 110V or 220V. I'm trying to wire it up for 110 but I'm not 100% sure how. Is low std 110V and high 220V? I believe I need to connect 1,3,8 to hot and 2,4,5 to neutral and ground to the ...
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1 vote
51 views

Potentiometer for Kitchen Fan

I'm exploring the possibility of building a potentiometer for my rangehood fan. The manufacturer (FanTech) of the fan actually sells one (EC-10VHL) but I'm having a hard time trying to find a ...
1 vote
49 views

Identification of 3 pin connector for the power supply of the TI silent Model 703/707 Data Terminal [closed]

I want to restore a TI Silent 700 model 703/707 that lacks the power supply. The power supply provides 20 VAC 35 VA with 3 pins ...
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AC Stepdown transformer blown troubleshoot

I've had a ring doorbell pro for about 5 years, it's wired directly to the following transformer output 1 & 4 (24v): It's using the original doorbell wiring, which rightly or wrongly, was wired ...
1 vote
223 views

Food for thought: Which person has truth in this discussion on capacity and AC? [closed]

I have stumbled upon interesting discussion in the commentary section regarding safety of electrical engineering in home environment. person1: AC voltage 'flows' even through insulator, fact. person2:...
1 vote
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How to find the power factor of a component when the combined power factor and one other power factor is known? [closed]

Problem: A 2000 volt-ampere with a power factor of 0.8 lagging is combined with 500 volt-amperes of synchronous motors. If the overall power factor is 0.9 lagging, find the power factor of the ...
97 views

DC bias vs AC voltage change rate on MLCC capacitors

I'm looking at this 10uF X5R ceramic MLCC capacitor. I know that ceramic capacitors which aren't C0G have an significant variation of their value depending on voltage, temperature, aging, and ...
22 views

A scheme to control a number of ceiling light bulbs being on with a single switch [migrated]

I have a ceiling light with two bulbs and only two wires (live and neithral) arriving to it (220-250v AC) and a SPST switch. I want to connect one bulb directly to those wires and I want the other ...
227 views

I'm getting 60-130V of output from a 5V voltage regulator. Does anyone know what went wrong?

I made a 5V power supply, but when I connected my multimeter probes to the output lines of the supply it read 60-130V. the voltage after the rectifier should be around 18-19V. If anyone can give a ...
39 views

How to measure power supplied by H-bridge inverter?

System description: H-bridge network of IGBTs (inverter) is used to supply power to a parallel LC circuit connected through matching inductor. It is desired to measure and regulate the power supplied ...
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Wiring Portable AC to Run at Max

I'd like to wire this portable AC to always run at max (compressor on and fan at max speed). I'm using it for a project where the temperature is going to be controlled by controlling the power to to ...
853 views

Transformer with same size symbol meaning

I Know these symbols mean a transformer step up or down: But what does this one represent since it has the same size on both sides? Part above taken from this schematic: And this also has me ...
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Are $v_{C}$ and $v_{L}$ in phase in an LC oscillator?

Looking at these figures, I can't help but to conclude that $v_{C}$ and $v_{L}$ are in phase! Why? Well, because $v_{C}=q/c$ I know this is wrong but why? Reference: https://shorturl.at/30NEu
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1 vote
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Is there a DC voltage on a transmitter power amplifier's output?

When studying the answers to Are my power calculations on this MOSFET Power Amplifier accurate? , I noticed this contradiction: If you integrate V * A, you get ...
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18 V AC to 5 V DC circuit design with battery

I’ll start by saying I have little understanding of electronic circuits. I have an old door phone to which I have connected a wireless switch in order to be able to open my door with a remote control. ...
52 views

Power Supply is arced and fuses opened

Note: PFC circuit is bypassed I have my own designed circuit and this circuit is get input of 220VAC/50Hz. Inside of circuit bridge rectifier and filters are exist with this circuit we get 320VDC. So ...
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84 views

How does an AC of 5100W (1.5 ton) capacity work without any issue with 1000W of total electricity load of my house? [closed]

I have one AC of 5100W (1.5 ton) capacity and I generally run it along with other appliances like fans, LED bulbs, TV and more. My house is sanctioned ...
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3k views

Second opinion on PCB design for relay made in Altium

Edit: I have added the updated PCB design at the bottom over this post (for anyone curious about the progress) And a big thanks to everyone who commented, it really helped me out a lot! Original ...
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Understanding Current Ratings in Step-Up Transformers

A step up transformer increases voltage while decreasing current because we can't get more energy than what we had in the first place. The thing struggles my mind is how his power has a current rating?...
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1 vote
61 views

Can someone help me with a LED light fixture puzzlement? [closed]

I have been buying and using LED bulbs from the Dollar Tree for many years. I have never had an issue with them in the past. Just the occasional burn out in my home office fixture because it stays on ...
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Power consumption in AC circuit

In a purely resistive circuit, maximum power is consumed. Why? Because, we say, current and voltage are in phase. While in a purely inductive circuit, power consumed in a cycle is zero. Because, ...
54 views

About power factor in circuits

We have an AC circuit with rms voltage V, and resistor R. Assuming that the circuit does noy contain any reactive components, Z=R therefore the rms current flowing in the circuit can be obtained by I =...
37 views

Dealing with High Voltage Low Current Transformer Inrush and bypassing a Thermistor

As a learning project, I am designing a power supply section of a guitar amplifier that uses a 120V Primary, 250V 45mA 40VA Secondary Transformer. Without any thermistor in-line on the main supply, I'...
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1 vote
68 views

How does the "earthing" system works in a UPS

PLEASE SEE EDIT 1 I want to know how exactly the earthing system works in a UPS, an example with by the ECOFlow RIVER 2. From their webpage it seems so simple, you charge the battery, switch the AC, ...
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Should this bare minimum TRIAC circuit light the bulb? [duplicate]

In trying to build a multi-channel, optoisolated, TRIAC based, switch module, I could not even get one channel to function properly. Trying to isolate the problem, I've reduced the circuit to this ...
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How to reduce notches in input AC voltage for Totempole Power factor Correction circuit?

Respected readers, I am working with a totem pole PFC circuit. In an experimental study, I face a problem of high-frequency notches in source voltage (Yellow one). I found an explanation behind this. ...
1 vote
35 views

Capacitance for power factor correction formula

I wrote a test the other day and the paper provided a formula for calculating the required capacitance needed for power factor correction. The formula: \begin{align} C = \frac{Q_c}{\omega V_{RMS}^2} \...
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178 views

Power transformer design calculations

I´m currently designing power transformers in a pretty basic way, using AWG tables for the section of the copper wire, and not knowing what are the real losses, just overdesigning. Three phase ...
43 views

Is steady state ac circuit analysis possible on a purely inductive circuit?

Is steady state ac circuit analysis possible on a purely inductive circuit? Consider the circuit: The dynamics should be: $$v_1 = L i^\prime + Ri + v_2\\ i(0) = i_0$$ Now, say we do steady state ...
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How to measure the voltage drop of the power supply when a large load (20 amps) is briefly connected for 20 milliseconds (one cycle of the waveform)

I want to measure the peak voltage of 240V AC supply line accurate to (±5%) within one cycle of the supply waveform, i.e. 20 milliseconds. What should be min. sampling rate and the ADC resolution (12 /...
55 views

LTspice AC/DC converter with DC/DC boost converter

So this is my first time using LTspice and I need to convert my (AC) Vin 11.5V to DC and then boost DC voltage to Vout 22.5V. I have a few givens and some I needed to calculate. I am struggling to ...
86 views

Can I use the mains itself as a ground? [closed]

Basically, an ideal EMC/EMI filter looks like the below circuit diagram. Ideal EMI filter circuit: Can I use the mains itself as a ground instead of using a physical ground? My take on EMI filter ...
826 views

Telecom cables for power transmission

Summary: Can I use abandoned telecom wire bundles as a 3-phase neutral? Our campus currently has underground AC cables supplying 2 legs of 3 phase wye power to a remote (50 ft away) building. There ...
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Can this circuit be used for an AC-DC emergency LED lamp?

Basically, this circuit is supposed to light the LED lamp from either AC or the battery. When there is AC available the bulb will glow with the power of AC and the battery will be simultaneously ...
48 views

MDAC AC reference input

I previously had a question on using AC reference voltage with a MDAC, But it has been addressed nicely in the answer below. How does the "Multiplying Bandwidth" specification relate to a ...
115 views

Are the answers of this questions all incorrect? [closed]

The question is: What is the voltage of the AC voltage source if Ammeter 1 measure 0.6A and Ammeter 2 measures 0.8A? R1 is 10 Ohms R2 is 20 Ohms (See image below) My solution is : voltage at R1: (0....
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How to wire a repurposed ac motor

I have an old garage door opener that I would like to repurpose. I would like to bypass the normal garage door logic and add an on-off-on switch. When switched to on1 rotates in direction 1, when ...
50 views

Deriving AC max. average power transfer, where am I wrong?

Starting with the Thevenin equivalent voltage $V_{th}$, impedece $Z_{th}$ and load impedence $Z_l$, the maximum average power transfer seems to be given by $\frac{|V_{th}|^2}{8R_{th}}$ but I'm ...
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Does LC circuit convert DC to AC?

I was experimenting with LC circuit (Class 12 - Physics, India) in CircuitJS1 Simmulator. Interestingly, the LC circuit given below was converting DC into AC. Circuit: Circuit Specifications: DC ...