# Tag Info

72

What you are really asking is how can electrical circuits cause small motions. After all, sound is motion of the air. The answer is that there are various ways electric fields or electric currents can cause forces or motions. These effects are harnessed in the design of various transducers, which exist to deliberately cause or sense small motions. ...

59

If you do this, then it will waste a lot of power: simulate this circuit – Schematic created using CircuitLab You'll also need a very large and heavy potentiometer because it will have to handle all the power that the speaker can handle. If you do this, then almost no power will be wasted: simulate this circuit The signal is very low power, and you ...

49

ALL current will heat the voice coil of a speaker. But AC current is useful to reproduce sounds (which is what a speaker is made for). On the other hand, DC current will produce the equivalent amount of heating as an equivalent AC current, but it will produce nothing but a fixed offset (versus moving the cone in and out to produce sound). And while you ...

38

A buzzer usually has an oscillating transistor circuit inside - to make the buzzing noise when voltage is applied, so it makes a tone. Applying voltage to a speaker will not make a tone, so you'd need an external oscillating circuit (e.g. a 555, or transistor oscillator). A speaker can play all kinds of sounds, however due to its built in circuits, a buzzer ...

34

The voice coil on a speaker is effectively a big inductor. It happens to also generate sound, but the loops of wire in a magnetic field make it act like an inductor. Inductors change impedance with respect to frequency. This is because any change in current through the system must build up the magnetic field in the coils. The faster you oscillate the ...

34

Yes. Figure 1. Cutaway view of a dynamic loudspeaker for the bass register. 1. Magnet, 2. Voicecoil, 3. Suspension, 4. Diaphragm. Source: Wikipedia. A DC component in the signal will cause: Bias of the speaker cone (4) and the suspension (3) from the neutral position. This means that the cone will reach the limit of its travel - or at least ...

34

Your linked description shows that the tweeter is intended to be used with a woofer for music reproduction. The description doesn't cover use of the tweeter as a specialist ultrasonic transducer on its own. The power rating indicates that the tweeter is intended to be used with a 350 W average/700 W peak audio amplifier driving both tweeter and woofer. For ...

23

This can be easier to understand if you look at the waveforms. In a push-pull, or bridge amplifier both lines are driven as shown below. Notice $L-$ is literally the inverse of $L+$ Similarly the other signal, $R-$ is the inverse of $R+$ The difference between the +/- voltages is that excites the speakers. Now, if you connect Opposites to one ...

21

It appears that the problem lies with the power ratings of loudspeaker components being the power rating of the system and not that of the individual component. For example, in the 1970s, Philips were specifying the ratings of individual speaker components. In later years, it may have been felt that specifying the system power would make it easy to select ...

17

Don't bother. 2.5 W is unlikely to hurt a 2 W speaker. It will just cause distortion. Somewhere in your audio chain there must surely be a volume control. Turn down the volume to the point where the sound from the speaker isn't distorted. The 2.5 W rating of a power amp is what it can put out, given the right signal and load. Put in lower volume, and ...

16

The frequency of oscillation is determined by the 470 kΩ resistors and 3.3 μF capacitors and will be roughly $\frac 1 {RC} = \frac 1 {470k \times 3.3\mu} = 0.64 \ \text{Hz}$. i.e., less than one pulse per second. The circuit has been optimised for the LED rather than the speaker. Modify the circuit so that the frequency is 100 to 1000 times higher and you ...

15

Generally, yes (confirmed by both theory and experiment) though probably not as effectively as they can lower frequencies. There are three primary factors: 1) The maximum frequency which can be produced by your source's DAC and associated anti-aliasing filters. This is usually a bit below the Nyquist frequency for your effective sample rate, how far will ...

14

The resistor is there to provide a DC path for the input bias current of the opamp. It is normally selected to be the same as the DC resistance connected to the other input, so that the bias current does not produce a voltage offset at the output of the opamp. But in this case, the effective DC resistance on the inverting input is only 1k||100k = 990Ω,...

14

The ability of speaker wire to carry the current involved is rarely much of an issue except a few quite unusual loudspeakers. The most notable in this regard was probably the Apogee Scintilla, with a rated impedance of one (1) ohm. That extremely low impedance translated to low voltage and quite high current. But, those are still remembered (thirty years ...

13

Your amplifier has a fixed output impedance and finite voltage swing. To get the most power out of it, the load impedance has to match the output impedance. Two speakers in parallel have half the impedance of one speaker. This is apparently too low for your amp to drive properly. Probably your "wallwart" supplies are collapsing under the heavy drain of ...

13

Sound consists of pressure changes in the air. You can generate these pressure changes using a loudspeaker. The loudspeaker generates these pressure changes (sound waves) by moving a diaphragm back and forth. This diaphragm is moved back and forth by a voicecoil consisting of a "pipe" with some electrically conductive wire wound onto it. This voicecoil ...

12

An ideal inductor or transformer might be a purely electronic component, but a real inductor or transformer produces a (rapidly changing) magnetic field. It is a design aim of such a component to keep that magnetic field within the component (for instance inside the ferromagnetic core), but that won't be achieved for 100%. The 'leaking' magnetic field will ...

11

I've replaced connectors on a lot of different headphones over the years. What I have found is that there is no standard for wire colors. They are all different. Consumer headphones, professional headphones, intercom headsets: they are all different. The proper way to check to see which wire does what function is to measure it. Put the headphones on ...

11

When someone is "buzzed" into the house, its with a relay (electro-mechanical) sound-maker. A relay, wired as normally closed, but able to break the circuit, is a buzzer. simulate this circuit – Schematic created using CircuitLab

11

I'm afraid that you are another Amazon victim. I note that you have linked to an Amazon ad rather than a manufacturer's datasheet which would explain how the device is rated and expected operating conditions. Our motto here is, "No datasheet? No sale!". I expect that a similar device from a reputable manufacturer might give the amplifier rating at ...

11

and 2. As I recall from some professional audio gear manual (made in 1980s) that I had to mess with, miswiring +/- at the speakers is the common reason for big "trenches" in the spectrum that are not correctable by the equalizer. The reason is, the speakers' ranges overlap somewhat and in the overlapping band they may pretty much fight each other. ...

10

LM386 needs an AC coupling capacitor on its input. If your input circuit is DC coupled, you disrupt the input biasing arrangements built into the amplifier. Instead of being centred, the output voltage is probably close to one of the supply rails, clipping the positive or negative half of the AC waveform, resulting in severe distortion. Insert 1 uF (or 10 ...

10

Beware the "audiophile" hi-fi market, there is a lot of very dubious product sold, often at crazy prices, to exploit and generally befuddle the innocent. In this category, we might include items such as: speaker cables that claim to have almost magical properties, including but not limited to, directionality. The function of a speaker cable is to ...

10

The power ratings for audio equipment are often completely bogus. Check out the amount of copper in a 350W motor (and note that a speaker is also essentially a motor, only the motion is linear instead of rotational): There's nothing in the photo for size comparison, so I'll just note the diameter is about 5" (13 cm). Guessing a power rating from a ...

9

For audio applications (as opposed to decoupling) there really aren't any high frequency transients to deal with, so a capacitor with a self-resonant frequency well above the audio range should be sufficient. An electrolytic capacitor is of course polarized, and only useful if the DC+signal is always unipolar. Also, an electrolytic capacitor has a shorter ...

9

Traditionally a buzzer was a device designed to make noise. Traditionally it would have been an electromechanical device. It would typically be supplied with DC and the oscillations would have been produced by an electromechanical process inside the buzzer. A speaker was/is a device used to reproduce sound from an electric waveform with the sound coming out ...

9

simulate this circuit – Schematic created using CircuitLab Figure 1. Two common amplifier arrangements. Can I safely assume this or are there any common or likely amplifier designs in which the black terminals might not all be at the same potential? Bridge mode amplifiers use two amplifiers - one an inverted version of the other. The advantage is ...

8

Since you're new to electronics I simplify here a little bit: OpAmps don't have the current drive capability to drive speakers directly. Speakers usually have a impedance in the low ohms. 8 Ohm is typical. A ordinary OpAmp won't drive much more than 50mA to 100mA. At 10V Signal that is roughly equal to an impedance of 1000 to 2000 Ohm. Much higher than ...

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