23 votes

Is there any way to measure sound intensity in decibels without using a microphone?

If your customers aren't electrical engineers, how would they tell a small microphone on your main circuit board from say an oscillator, opamp, or voltage regulator? So any customer that only buys ...
really not Constantine A. B.'s user avatar
22 votes
Accepted

Normal capacitor vs. audio capacitor

Let's forget about audio for now and try to find where the price difference lies in the specific products you mentioned, first. Main reason: the ebay seller of the Vishay cap seems to mistake his ...
dim's user avatar
  • 16.1k
18 votes
Accepted

Why would this microphone only work while touching the volume control?

If it is a grounding issue, touching it could change the amount of hum, buzz or interference. However you say "It only works if you keep your hand on the volume knob" which I interpret as "there is ...
bobflux's user avatar
  • 77.5k
17 votes
Accepted

Does a pickup microphone work in space (vacuum)?

A contact microphone is basically an accelerometer. It does not require any air for its operation.
Dave Tweed's user avatar
  • 173k
15 votes

Can a comparator (LM393) be used as an amplifier?

Take a look at the basic schematics of the internals shown in the data sheets for the LM324 (regular op-amp) and LM393 (comparator) respectively: - The input stages are both pretty similar but the ...
Andy aka's user avatar
  • 457k
14 votes
Accepted

Using a microphone from the 1930s

A quick look at the Radio Museum pictures and descriptions makes it look like it ought to be fairly easy to hook up. Here is the picture of the connections from the Radio Museum: You provide it with ...
JRE's user avatar
  • 71.4k
13 votes

Are there any certifications required when selling a home-made microphone in the EU?

CE marking is required for most products sold in the EU. In many cases, the CE marking itself does not inherently require some external agency to deliver some kind of agreement or certification: it is ...
jcaron's user avatar
  • 2,064
12 votes
Accepted

Is there any way to measure sound intensity in decibels without using a microphone?

You need to improve the definition of your problem. Privacy Does that mean any talking is unintelligible? The fact that some sounds can be heard, at a specific time, even if they are unintelligible as ...
Neil_UK's user avatar
  • 166k
11 votes

Can a comparator (LM393) be used as an amplifier?

The LM393 modules you see advertised on eBay aren't microphone amplifiers as such. They are advertised as sound detection modules, which deliver a (more or less) digital ouput. That module has an ...
JRE's user avatar
  • 71.4k
11 votes
Accepted

Can I connect multiple electret microphones for better gain?

I am a technician at a boutique mic company. I like to build electret mics in my spare time. You can increase sensitivity, gain, and signal to noise ratio by running multiple electrets in PARALLEL-...
Zachary Alan Stewart's user avatar
11 votes

Why would this microphone only work while touching the volume control?

Repair questions are off-topic on this site so let's make it an education question. Figure 1. Potentiometer terminals 1, 2 and 3. simulate this circuit – Schematic created using CircuitLab ...
Transistor's user avatar
  • 176k
10 votes
Accepted

Will this phantom power circuit work?

The second schematic is right. The first has polarity the wrong way around and a dead short across the signal lines. You've also got the polarity wrong on the LM386 so be careful! The Zeners are a ...
Transistor's user avatar
  • 176k
10 votes

Normal capacitor vs. audio capacitor

I was curious, because I have the feeling that a component being "audio" is partly driven by belief, but in so many cases there are underlying reasons for that belief to be sensible. In the most ...
mehmet.ali.anil's user avatar
10 votes
Accepted

Why is the collector feedback bias popular in electret-mic preamp circuits?

Most of the hobbyist circuits you find by googling are crap originating from dubious tinkering and then copied from each other. The bias level of this circuit is not very predictable from BJT to BJT (...
Spehro Pefhany's user avatar
9 votes
Accepted

Phantom Power supply for Electret mic

You have roughly the right idea, but you should use a resistor divider instead of a single resistor to bring down the voltage. With your setup, the microphone is still subjected to high voltage, ...
Olin Lathrop's user avatar
9 votes

Is there any way to measure sound intensity in decibels without using a microphone?

Any device or transducer that can convert sound to electrical signal is by definition a microphone. Even capacitors can exhibit microphonics and can ruin your signal by converting audio or mechanical ...
Justme's user avatar
  • 149k
8 votes

Normal capacitor vs. audio capacitor

Question: what kind of difference is there between such a capacitor, for "audio applications" First "audio application" doesn't mean anything. A capacitor can serve many different uses, for example ...
bobflux's user avatar
  • 77.5k
8 votes
Accepted

Why is the electrolytic capacitor not polarity sensitive?

An aluminum electrolytic will handle a reverse polarity of about 1 volt or so. The cap probably never sees anything near that. This appnote from Nichicon shows that under 1V the capacitors don't ...
Robert Endl's user avatar
  • 2,207
8 votes
Accepted

Acoustic localization

Does that sound reasonable? Or am I missing something? Theoretically SPL halves with a doubling of distance so, the extra attenuation over the distance range of 0.5 metres to 3000 metres becomes: - $...
Andy aka's user avatar
  • 457k
8 votes
Accepted

Are microphones with flatter frequency response charts better at picking up frequencies?

In general, the frequency-measurement would be quite accurate even with a low-quality microphone. This would only be affected by the accuracy of the clock used to control the sampling in the analog-to-...
sondre99v's user avatar
  • 821
8 votes
Accepted

Trying to relate microphone sensitivity and SPL

A microphone specification of \$-44\:\text{dBV}\$ implies a reference of \$1\:\text{Pa}\$ or \$\approx 94\:\text{dB SPL}\$ and the V is with reference to \$1\:\text{V}_{_\text{RMS}}\$. not peak. The ...
jonk's user avatar
  • 77.9k
8 votes

What is the purpose of these passives in a microphone pre-amplifier circuit?

The first group are bias for the microphone capsule. the top 2K reduces supply noise into the capacitor, and the bottom 2k provides bias current The second group set the bias voltage for the op-amp ...
Jasen  Слава Україні's user avatar
7 votes
Accepted

What is the best preamplifier circuit for electret condenser microphone?

Add a resistor in series with the 100 uF capacitor across R3 as shown below: - Without that resistor there is nothing that defines the AC gain of the amplifier and the effect of the 100 uF without ...
Andy aka's user avatar
  • 457k
7 votes
Accepted

Anti-eavesdropping Electronics?

Eavesdropping microphones can be jammed by overloading them with ultrasonic sound waves. The microphone and the front end analog circuitry, when overloaded, can generate noise in the audible frequency ...
Mark Leavitt's user avatar
  • 5,664
7 votes

What is the purpose of these passives in a microphone pre-amplifier circuit?

I refer to this datasheet. Starting with the microphone and its power/biasing: simulate this circuit – Schematic created using CircuitLab The microphone drops a few tenths of a volt (I assume 0....
Simon Fitch's user avatar
  • 35.2k
7 votes
Accepted

Are there any certifications required when selling a home-made microphone in the EU?

Rode make microphones and here's an example of one of their CE declarations of conformity: - I've added a likely picture of the product from here: - However, no need to feel this needs a lot of work ...
Andy aka's user avatar
  • 457k
6 votes

Can a comparator (LM393) be used as an amplifier?

A comparator lacks compensation so, in general, it cannot be stabilized to act as an amplifier at unity gain easily, if at all, depending on the internal construction. However, in the particular ...
Spehro Pefhany's user avatar
6 votes
Accepted

Why does my electret microphone amplifying and filtering circuit output so much noise?

There are a number of problems with this circuit: The input to the reference is not filtered. R5 and R4 make half the supply voltage, but also transfer half of whatever noise is on the supply. ...
Olin Lathrop's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible