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9 votes

Could RS-232 data be carried over a standard 3.5mm audio/aux cable?

RS-232 levels and rates are not very different from audio. Probably there is no such thing as an audio cable that cannot handle serial at say 115.2kbps. Things start to get iffy when you're talking ...
Tim Williams's user avatar
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7 votes

Could RS-232 data be carried over a standard 3.5mm audio/aux cable?

It raises the question, in theory could RS-232 communication be achieved through audio cables? Yes. If the baud rate is quite low, or the cables are relatively short, then audio cables can handle ...
Tanner Swett's user avatar
  • 3,315
7 votes
Accepted

Mixing audio signals: pros and cons of using resistors instead of an op-amp

What I don't understand is the pros/cons of one over the other. If you use an inverting op-amp summing mixer then, because of the virtual earth, if you remove one channel input, it won't affect the ...
Andy aka's user avatar
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5 votes
Accepted

Connecting multiple audio crossovers

This will not work as planned. The second crossover loads down the first crossover. This has the effect of changing the frequency response and the impedance. In principle, you can design the first ...
MOSFET's user avatar
  • 2,017
4 votes

Mixing audio signals: pros and cons of using resistors instead of an op-amp

The two resistor approach gives you the average of the two signals. $$ V_{out} = \frac {V_1 + V_2} 2 $$ You can see this clearly if you imagine that at some instant \$ V_1 = 1 \ \text V\$ and \$ V_2 = ...
Transistor's user avatar
  • 175k
4 votes
Accepted

Likely source of noise, given circuit is quieter connected to a PC?

You're using unfiltered power supply voltage to set the DC bias of the opamps, which means you're listening to your 9V power supply. On the first opamp, using a signal source with low impedance would ...
bobflux's user avatar
  • 75.5k
2 votes

How to isolate audio signals from each other using op-amps with the same single supply?

First up, your TL074 needs split supplies - I see you are using IC1D as a voltage follower to generate an artificial "ref" at more or less mid rail "Vref". You are effectively ...
danmcb's user avatar
  • 6,879
2 votes

Connecting multiple audio crossovers

Passive filters are designed for certain signal source output series impedance and for certain load. Your 2nd filter is not a good load and it gets its input from a wrong kind of source. Get a single ...
oneprivate's user avatar
2 votes

How to isolate audio signals from each other using op-amps with the same single supply?

The way you have wired up IC1B, with the inverting input connected directly to a fixed potential, there's no negative feedback, and it won't behave linearly. It's a comparator in this configuration. ...
Simon Fitch's user avatar
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2 votes

Mixing audio signals: pros and cons of using resistors instead of an op-amp

Introduction Your question is specific and you got good specific answers that will help you solve the problem. But I suggest you take another step further to realize the "philosophy" of ...
Circuit fantasist's user avatar
1 vote
Accepted

RCA RMS voltage

0 dBm is 1mW, to convert into voltage you need to know the impedance, which in this case is "600 ohms phone line", so 0dBm in audio context is 0.775 V RMS. In a RF context you'd use 50 or 75 ...
bobflux's user avatar
  • 75.5k
1 vote

Could RS-232 data be carried over a standard 3.5mm audio/aux cable?

An ordinary audio 3.5mm TRS plug to plug cable may work, but is more likely to result in both devices talking on the same wire, and listening on the other, so unable to communicate. I suggest getting ...
Peter Bennett's user avatar
1 vote

Could RS-232 data be carried over a standard 3.5mm audio/aux cable?

Audio cable is just cable like anything else. RS-232, being a 60-year old standard initially, does not have much special requirements for the cable, except the cable having low enough capacitance. So ...
Justme's user avatar
  • 144k
1 vote

Mixing audio signals: pros and cons of using resistors instead of an op-amp

A resistive mixer used directly on the input has a few downsides. The mixing ratio depends on the impedance of the sources. Essentially the impedance of each source adds to the resistors in the mixer....
Peter Green's user avatar
  • 22.1k
1 vote

How to isolate audio signals from each other using op-amps with the same single supply?

You have audio ground "Vref" which is tried to be held stable by IC1D. At the same time IC1A does its best through C1 to make Vref to follow the +sign transients of the audio. The current ...
oneprivate's user avatar
1 vote

Resistors in audio circuit

When you say the audio is louder when the switch is open there are two possibilities. You mean that when the switch is open only Audio #2 is being used, and when the switch is closed only Audio #1 is ...
GodJihyo's user avatar
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1 vote
Accepted

Switching between audio sources with transistors. Mimicking a SPDT switch

What you're describing is a so-called "analog switch". They're so common in audio circuitry (and other analog circuits as well) that they're available as ready-made chips which you just have ...
Jonathan S.'s user avatar
  • 17.8k
1 vote
Accepted

Aluminium electrolytic capacitors in an AC circuit

The output does not reverse in polarity so there will be no capacitor damage. That amplifier works on single supply. It means that if you feed on 12V supply, the output from the chip will idle at 6V. ...
Justme's user avatar
  • 144k
1 vote

No DC offset observed in the CE amplifier circuit part

First a suggestions on drawing schematics in LTspice, set up your supply voltages apart from the rest of the schematic and label them, then use the labels in the circuit. This makes the schematic less ...
GodJihyo's user avatar
  • 22k
1 vote

No DC offset observed in the CE amplifier circuit part

This shows that the there is no DC offset observed in the circuit. You are directly coupling the output of op-amp to the base of Q5. This will override the bias provided by R4 and R6, as long as the ...
Math Keeps Me Busy's user avatar
1 vote
Accepted

DIY project - Listen to Guitar Amp on a USB headset

What you're asking for is not a simple wiring hack. The Kraken USB headset, from the USB point of view, is a digital device. In fact the Kraken has a DAC in it. For it to work, it needs a digital ...
hacktastical's user avatar
  • 52.7k
1 vote
Accepted

Recommendation for type of switch

A 4PDT switch should do it, assuming you want to switch both leads and not have a common between the amps. simulate this circuit – Schematic created using CircuitLab In the position shown, AMP ...
GodJihyo's user avatar
  • 22k
1 vote
Accepted

USB Audio interface 50Hz + harmonics noise when either laptop or speakers are plugged in

You have a charger which has a grounded plug. But you are connecting it to wall socket that doesn't provide ground. It needs to be connected to a wall socket that provides a ground. Most likely it ...
Justme's user avatar
  • 144k
1 vote

Coupling class-D output to audio input of another device

I was thinking of using an audio transformer across the class-D output and a pot between the output of the transformer and ground to feed the input. Is this my best option or are there better ...
Andy aka's user avatar
  • 452k
1 vote

Likely source of noise, given circuit is quieter connected to a PC?

You have a power distribution problem. Example 5V source reference is ground but all devices using 5V are referred to DGND. Using a single point ground (I can't find it on the diagram) in this way ...
RussellH's user avatar
  • 14.6k
1 vote

Likely source of noise, given circuit is quieter connected to a PC?

Although C10 and C13 provide capacitance between the 9V input and ground, these are (most likely) electrolytic capacitors with high ESR. The 78L05 can oscillate if its input and output are not ...
Math Keeps Me Busy's user avatar
1 vote

DIY guitar amp cabinet selector switch

As mentioned above you have to provide load at amplifier output (it's just resistor but it should be rated for higher power) if amp you "unplug" is turned on but I don't think it's good idea ...
user363431's user avatar
1 vote

Can an ESP32 be fed an audio signal and then output that audio to a Bluetooth speaker?

According to the A2DP Source (Music Sender), yes it is possible. You need to set the Bluetooth device name (sink) that you want to connect to and a callback that can supply PCM audio data to be sent. ...
user85471's user avatar
  • 271
1 vote

What is the safest and most noise free grounding method floating or non-floating for audio plugs & circuits on 2U aluminum case and SMPS

I solved the problem by getting rid of the switching power supply and went with a simple step-down transformer, full wave bridge and capacitor. Now It is noise free. I ended up floating the audio ...
Jim Dandy BOA's user avatar

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