# 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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### I need 6 volts AC from a battery, and have no power source available [closed]

For a a house in the jungle, we want to install a water filter system. The filter system works @ 6 volt AC. There is no power source available. Any suggestions? I want to use a battery pack of 6 volt, ...
54 views

### Current in secondary side of step-down welding transformer

I am confused about the use of a step-down transformer in a welding machine. The transformer steps down the voltage, let's say from 220V on the primary to 12V on the secondary. It is said that it ...
1 vote
365 views

### Circuit only works while touching the ground

so I am doing a small ESP8266 relay module. The relay is used as a SPDT switch so you can turn on the light with a normal switch on the wall but the module can shut them off after no motion is ...
255 views

### Calculate active power

Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab -> -> No to find the apparent power of R1 we multiply V*I -> The active power is <12W. ...
594 views

### Explanation of a sample circuit for the FL5160 dimmer controller

While looking for dimmer circuits, I stumbled upon the FL5160 dimmer controller and it's specification. The example schematic (for example, the 3-wire circuit on page 3) connects DC ground to the ...
1 vote
830 views

### Designing PCB with AC Live and Neutral on two layers

I'm designing a smart socket that will route 240V AC Live and Neutral to a voltage regulator and also to a relay that will control the current flow. Due to the limited space, it will be easier to ...
256 views

### Diode in series with a resistor an in parallel with another resistor

I have been facing some troubles with this problem. My main concern is that if Vab = 0.7 (when V(t) > 0 V,) will the diode conduct? I think that isn't the case, but if that so I don´t know how to ...
2k views

### If AC current can flow through a capacitor, why can't it flow through an open circuit?

It is known that: AC current can flow through capacitors A wire has some inherent capacitance A capacitor is the same as an open circuit with plates at either end, and the size of the plates ...
9k views

### splicing ac adaptor cord which is positive and which is negative?

i lost my original asus router power adaptor. so i have a 12v power adaptor with a tip that fits my 19v asus wifi router, and i have a old 19v power adaptor that has a tip that is too small to fit my ...
3k views

### How to wire an old single phase AC brushed motor to be reversable

I have searched several forums and found a lot of interesting stuff, but nothing yet that really applies to my situation. I have an old Westinghouse FH motor 1 1/2HP single phase brushed AC motor. ...
68 views

### Circuit that outputs signal A when AC sine is positive and signal B when AC sine is negative

I need help designing a circuit that outputs Signal A high when AC sine wave is positive and Signal B high when the sine wave is negative. It's part of a larger project that cycles power in a ...
33 views

### Repurpose adjustable standing desk linear actuator for a project on my truck [closed]

Disclaimer: fairly limited experience with electrical engineering. I'm currently making a deck for my snowmobile that will sit in my truck bed - a 'Sled deck'. Nice sled decks have telescopic sides so ...
1 vote
45 views

### Multisim simulation insight

I want to simulate an AC circuit in multisim. I would like hints or articles on how to simulate complex-valued impedance, for example this circuit: I don't have an option in multisim 12.0 , to have a ...
1k views

### How does one determine the type (AC v. DC) and operating voltage of small motors?

I've become fascinated by Rolling Ball Sculpture (RBS) and plan to start building my first one soon. Typically a RBS uses a low-voltage, low-RPM motor to carry the marbles to the top of the structure ...
1 vote
12k views

### Can I give DC 12V to a AC 12V input?

I have a circuit that takes 12V AC as an input but my bench power supply only delivers 12V DC, is there any issue if I give the device DC instead of AC? (Same voltage) Straight after the input there ...
282 views

### "Pull-Down Resistor" in AC circuit

Background I have an Fridland AC doorbell that I am about to make "smart". My approach is to connect a device named a shelly uni inside the doorbell that ...
978 views

### Why does a full-wave bridge rectifier have noisy output with no load?

Purely academic question: I have a little bridge rectifier made out of four 1N4001 diodes, being fed by a transformer putting out 12VAC. When I run it without anything else attached to it, the ...
140 views

### If I connected a voltmeter across the source capacitor combination of a RLC AC series circuit, what maximum voltage would it read?

Since phasors sum up vectorially, I believe it is going to read $(V²+(V ᶜ)²+2VV^{c}\cosθ)^{\frac{1}{2}}$, where $V$ is the source maximum voltage, $V^{c}$ is the capacitor maximum voltage and \...
713 views

### How to determine the right trip point of thermal cutoff for 1/4 hp 3A 115V single phase ac motor

The Thermal fuse blew in my Ryobi DP102L drill press motor, while I was drum sanding. There were no markings on the fuse. The single phase induction motor is 1/4hp 3A (no load) 1750rpm on 115V AC, ...
1 vote
4k views

### Use ACS712 current sensor in two-phase electrical system

I'm thinking about using the Allegro ACS712 current sensor for measuring house equipment current consumption (for example TV). The issue I'm facing is that my house energy supply is built around two ...
47 views

### How to add LED array to 110VAC AC circuit that includes small motor

I'm building a small machine that uses 110 VAC to power a small (14 W) motor. I want to add an LED array that a switch activated by the motor turns on and off. (The motor will also be gearing some ...
25 views

### Measuring AC current using LEM HAIS 50P

I am working on LEM HAIS 50P current sensor and I'm using it for measuring AC current. I have an offset of 2.5V, so at 0A the output of the sensor is 2.5v which is as expected but if I increase the ...
1 vote
46 views

### Residual current relay continuity

Even if the leakage current relay is 300 mA, it cannot provide human protection in such a case. Then, if I make a circuit like this, if there is already 270 mA leakage, then if there is an extra 30 mA ...
1 vote
486 views

### 230V AC triac dimmer for single phase motor and LED lightbulbs

I successfully developed produced my first AC Triac dimmer board, which works fine on resistive load like regular light bulbs. It also works fine for an AC motor the last 2 years. However, in order to ...
1 vote
63 views

### How to connect a 12V electromagnet to 220V power adaptor

I'm not very familiar with electronics, but I want to create a basic automatic pet feeder for my outdoor dog house. My idea is simple: a wooden box with a floor that drops at a set time, controlled by ...
159 views

### How can I convert a Noma Ornamotion Christmas tree ornament motor to USB power?

I have a small motor that plugs into the light socket of a incandescent mini light set and spins an ornament. They were called Ornamotion spinning motors. Now that we're moving to LED, the LED sets ...
3k views

### Minimum current level to trip a GFCI

TLDR I originally asked "Minimum current level to trip a GFCI"? But the answers pointed out that my biggest problem in this question is that I shouldn't use a general-purpose DMM to find an ...
218 views

### How are hybrid parameters defined?

I was reading about H-Paramters and how they were essentially defined and couldn't quite understand this bit in the picture below. Here are my questions: Shouldn't Δv_BE = Δv_be as V_BE is constant (...
58 views

### Can we sell 110V equipment without NRTL certification in a US market?

Only in some places. Weight scale product certification NRTL 110VAC
61 views

### Complex equations in AC RLC circuits spiralling out of control

I'm trying to solve the following circuit. I tried using superposition to find Thevenin at V_o. First I solved for V_o with the current source and dependant source, then I solved for V_o with the ...
61 views

### What motor will work best as a generator for low torque input?

I would like to know what kind of motor will work best as a generator. The input will be RPM with low torque around 20-40 N*mm (this is the minimum.) It should be possible to rotate the motor at this ...
1 vote
75 views

### Do Kirlian setups work with DC power? [closed]

I have been trying to build a simple Kirlian setup, and I've been trying to make my flyback transformer work, to no avail, so I shifted to use the small black 3.7 V to 400 kV transformers (as they ...
1 vote
68 views

### How much clearance do I need for a terminal block that will run at 240VAC, 10A max?

To start off, I don't have any experience with designing PCBs for high voltage relays/switches. I'm currently designing a PCB that has a relay on it that will be used to turn on and off a device (like ...
17 views

### ZMPT101B module producing VDC even with AC source disconnected

I am trying to use ZMPT101B to measure 110V AC but even after calibration and using multiple sketches when I power off my AC source it measures some AC voltage (or in other words a signal is still ...
142 views

### Is touching a neutral wire safe?

Yeah, I know, it is such an old question, so many discussions on this topic, but I cannot realy find an exact answer in the Internet. I live in Ukraine, where we have 230V AC outlets, as in most ...
401 views

### Power amplifier simulation and real time experiment mismatch problem

Thanks in advance to anyone who will take the time to read my first post here. At present, I am doing a simulation of a power amplifier in LTSPice. The schematic and relevant files are uploaded in a ...
4k views

### Fan speed and power consumption

Really basic question that I've struggled with for a while. In low-cost fans, a series of mechanical buttons select fan speed. I assume each button is connected to a specific resistor which limits the ...
132 views

### Airport runway lighting: What is constant current in relation to alternating and direct current?

I’m an apprentice electrician currently replacing runway lights and pulling new wire at a small international airport. When I asked I was told they are 5kV direct current. Okay… simple enough. What ...
911 views

### Optocoupler 4N25 cut and saturation for zero crossing detector circuit

This is my first time working with an optocoupler and I'm trying to find the right resistors for a zero crossing detector circuit that has a 4N25 optocoupler, but the values I've calculated are not ...
171 views

### How to sense the presence of AC voltage that could vary from 17 V to 230 V?

I have a requirement to sense the presence of AC voltage, that could vary from 17 V to 230 V, and trigger a TLPxxx series optocoupler. The wide voltage range poses a problem in the choice of a ...
274 views

### AC to DC conversion, how to keep the voltage same?

I have an amplifier board. The maximum input voltage is -40V 0 +40V DC. I have a 30V 0 30V 5 amp transformer. When I read the DC voltage after rectification, it shows around -45V 0 +45V. So what is ...
56 views

### Should Liquid Level Sensors be supplied AC or DC

Liquid level sensors often use two probes, when the resistance between those two probes changes with reference to the level of the liquid between them, that change is resistance is read as change in ...
1 vote
122 views

### How would this circuit work?

This is a frequency doubler from a graphene frequency doubler paper if anyone know the working with substituting a normal transistor instead of a GFET?
2k views

### Which wire is hot?

I have an analogue oscilloscope that had its power cable head chewed off by something. Before I replace the cable, I want to be 100% sure which side of the cable is hot and which is neutral. This is ...
25 views

### Current rating of relay with daisy chained parallel power supply

I am using relays to turn on and off appliances that may work on mains or DC voltage. My question is in regards to mains voltage. I am hooking up the live wire to the com pin and the live of the ...
1 vote
2k views

### How to connect an AC line filter

I am trying to connect an AC line filter (rated for 115/250VAC) on the load side of a 24VAC transformer (part# BPD2G, datasheet here). The first filter model I used is Delta's 03DBAW5. From the ...
43 views

### Devices with AC to DC inverters given a DC current

This is mainly a question to suffice my curiosity, but if I gave a device that has a plug for AC current (like a wall socket) but gave it DC current instead, what would happen??
78 views

### Is measuring 220v AC current from wall socket with multimeter safe?

I've purchased a cheap Aneng multimeter (model SZ08). Since I'm not an expert in electronics, I have some questions related to the usage of this device. For instance, I wonder if measuring 220v AC ...
1 vote