Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [ac]

23 questions
10
votes
4 answers

Does a transformer use power when output isn't under load?

I was reading about how AC to DC converters work with a step-down transformer and then a diode bridge to convert the lower, stepped down AC voltage into DC. What I don't understand is since the input AC appears to be connected to the primary coil of…
jhabbott
  • 5,990
  • 6
  • 29
  • 63
7
votes
1 answer

Is a 3 Hz beat frequency from my neighbor's HVAC a sign of a malfunction?

I'm being annoyed by a pulsating hum which comes from my neighbor's HVAC system. I read up a little on the design of HVAC systems and I came to a tentative conclusion that what I'm hearing is a compressor being driven by an AC induction motor. A…
Metamorphic
  • 173
  • 4
3
votes
1 answer

Arduino DAC to Speaker

I'm working with an Arduino Due's two DAC pins. I want to output to a single 4W 5.7Ohm speaker to test my code, with the intent of eventually outputting to a set of speakers (woofer, mid-range, and tweeter) for better quality for frequencies between…
Richard Bernard
  • 33
  • 2
3
votes
0 answers

Understanding transformer secondary winding

I purchased a step down transformer from a junk yard. I tested the transformer and it works but I am confused as to the secondary winding. The primary side has these markings G 0V 100V The secondary has these markings 37V 18V 0V 6V 0V On the…
eeguyee
  • 43
  • 2
2
votes
4 answers

How does single-phase AC synchronous motor work?

In a recent question of mine about microwave plates, jpa correctly identified the type of motor used for microwave plates as a specific variant of AC synchronous motor, equipped with gears that reduce the speed to some 5RPM. A single-phase (or…
SF.
  • 6,153
  • 23
  • 43
2
votes
1 answer

Calculate amount of evaporative coolers needed to cool down an area

I have a task to create a software that calculates how much evaporative coolers are needed to maintain a certain temperature in a given room. I need to create a simple form, where variables are next : 1 - Location (i can fetch dry and wet bulb…
Vulegend
  • 23
  • 2
2
votes
0 answers

Breakdown voltage of electronic devices

Diode and transistor have reverse breakdown voltage. Are these devices permanently destroyed under such voltage? Also, do these devices have breakdown voltage when AC voltage is applied? How much AC voltage and frequency these can tolerate, say…
ijhuyg
  • 21
  • 1
2
votes
1 answer

Are there any variable frequency drives that work digitally?

By this I mean can any DC to AC variable frequency drives invert digitally (no moving parts) and if so how do these work? Is this possible for both sine and square wave inverters?
SRawes
  • 240
  • 1
  • 10
2
votes
0 answers

What is the maximum frequency of an AC current?

I saw that the rpm of a synchronous motor is proportional to the frequency of current alteration and I was wondering if there is a theoretical maximum frequency (regardless of magnet strength)? Also could changing the frequency be used to control…
SRawes
  • 240
  • 1
  • 10
2
votes
1 answer

Mechanically increasing RPM of ac induction motor

If you spin the stator of an AC induction motor than would the rotation of the rotor increase? Or would it have a different affect such as moving with a higher force?
SRawes
  • 240
  • 1
  • 10
1
vote
1 answer

Will AC Motor Maintain Speed of Descending Object

Suppose we have an AC motor which needs to lower an object at a set speed. We use a PID loop to determine and correct positional errors. Presumably the PID loop will keep the current low as most of the work will be done by gravity. By lowering or…
M-R
  • 137
  • 1
  • 1
  • 3
1
vote
0 answers

Household 3 phase devices

So, I'm not sure if this is the right place to ask this, but have been working on modifying a lawn mower robot that has, for roughly 3 years now been stored under less than favorable conditions. As a result, the motor driver is broken, and I don't…
Mat NX
  • 265
  • 2
  • 4
1
vote
1 answer

Design of a hydrogen and corrosion sensor query

I’m designing a hydrogen and corrosion sensor. A thin film changes resistance based on hydrogen concentration. Then the capacitance between two electrodes will change depending on substrate thickness (corrosion). AC analysis can be used to see a…
Ellis123
  • 11
  • 1
0
votes
0 answers

Convert a 3 poles AC/DC battery charger into a 2 poles DC power supply?

I have a battery charger with a positive pole, a negative pole and a common pole, see the below diagram. The output voltage is as follows: positive-common 5V DC negative-common 5V DC positive-negative 0V The battery specs are 10V DC at 1.5 Amp h,…
Jared Lo
  • 101
  • 1
0
votes
0 answers

What is the best way to measure a biphasic current pulse?

Apologies if this is a basic question. I wanted to know the best way to visualize a biphasic current pulse. Can I do this with an oscilloscope? The other question I had is, is a biphasic pulse current DC or AC? Or are pulse currents a different…
Simon
  • 1
1
2