All Questions
78
questions
1
vote
2
answers
35
views
Why does the volume of the preamplifier change when a second audio signal is mixed? [duplicate]
I have two audio signals leading to the amplifier input: the first one comes from the preamplifier, the second one from the audio output of a smartphone/tablet device. Both have a resistor and a ...
- 53
1
vote
1
answer
71
views
Sharing ground between circuit and audio input?
I'm trying to build a VU meter circuit, and followed this guide/diagram (link)
I understand how the circuit should work in theory (mainly the OP-amps and the "logic"), except for the ground ...
0
votes
1
answer
117
views
Is it possible to add headphones to a Geiger counter circuit?
The main problem is as follows. From what it seems, most Geiger counter circuits opt for a piezo clicker. I'd like to just plug in a 3.5mm audio jack and be able to hear when pulses come in. The ...
- 11
1
vote
1
answer
85
views
Should an unused audio input be left floating or connected to GND?
I am designing an audio circuit with multiple signal inputs through a jack connector that may not always be active simultaneously. In this case, is it better to connect them to GND when not in use to ...
- 53
2
votes
1
answer
71
views
Signal Processing Question--old school [closed]
I have a signal generator that creates a mostly 8kHz sine wave signal, with a couple quirks. It repeats in a 96ms pattern. Output is 220mV into a 1-20 ohm wire. It is used to provide wire guidance ...
- 21
0
votes
1
answer
135
views
How would you compute Fourier transform of a real world signal where the signal keeps getting updated (not a static one)?
A very naive question: How do we use Fourier transform for real world signals - for which you have the information only up to the present instant (and the present time keeps moving continuously)?
The ...
- 3,032
0
votes
0
answers
47
views
Data-set creation and signal processing
I'm taking a digital signal processing course and I have a project to create a data set with a microcontroller and process it for this course. I want to count only dog bark for example not dog growl. ...
- 3
0
votes
0
answers
46
views
Analog audio splitting with sampling
I want to build an audio visualizer and have the audio passthrough to another audio jack, so I do not have to mess with external splitters.
I have come up with the following schematic:
Should I be ...
- 101
0
votes
2
answers
193
views
Drive audio signal through SSR
This question is related to one of my older questions: Push to talk mic over music
I was thinking how to get rid of the mechanical action of the relay so I wanted to know if it is possible to drive a ...
- 127
4
votes
4
answers
239
views
Name and cause for phenomenon in microphone preamp output as seen on scope screen
What might cause 1 kHz sinusoidal signal to change such as seen on the screen? How is this phenomenon possibly called?
I have quite a lot of hand microphones with built-in opamp preamp and electret ...
- 63
0
votes
1
answer
169
views
Transistor for Signal Attenuation
I've been considering a circuit that could be used as an equalizer for an audio signal. Specifically, I'm planning on using a set of filters (a cross-over) to split the input into respective channels,...
- 125
2
votes
5
answers
2k
views
Series or parallel LC in an AM radio?
All transistor radio circuits (not crystal) on the internet seem to use an antenna and parallel LC circuit. Why does no one use series LC circuits to select stations?
To my knowledge, series LC ...
- 570
0
votes
0
answers
48
views
Identifying and finding a replacement audio signal transformer 50 ohm / 0.5 ohm
I am trying to identify and find a replacement for the attached transformer. The green/white leads with the red center tap have a 50 ohm resistance. The side without the center tap has a 0.5 ohm ...
- 11
1
vote
0
answers
104
views
opamp single supply output AC (audio) voltage limit
I build non-inverting op amp with single supply voltage cca 9V. The basic scheme is shown in the figure below:
How to limit output AC signal if the base DC voltage is at half the supply voltage 4.5 V ...
- 71
5
votes
3
answers
1k
views
Do DSL / ADSL modems have an ADC with ~ 2 MHz sampling rate?
For fun and no real practical use, I'm trying to design a DIY modem that can transmit data over an audio line, like old 56k modems did. I'm studying how to pack bits of data efficiently in a 1k-15k ...
- 1,946