That's the TS want to reducing the parts, so if he care about the quality then he should keep that, sometimes the numbers of parts and quality of sound that you can't have both, when you change any components of TL431 then it could be affecting the output voltage, that's why I don't want to change the components of TL431, only adding some parts through the capacitor, so you can see the easy way I suggested.

With the TL431 electret booster as published in Elektor a few years ago, I included the current draw of the electret capsule in the overall setup. Initially I included a 47k pot as the bottom resistor in the DC nfb path so the output operating point could be set just so.

With DC coupling between the capsule and TL431 - its as good as it gets. Any DC blocking/coupling capacitor will have a tradeoff between size/cost and low frequency roll off. Most audiophools claim that coupling capacitors taint the audio to a greater or lesser degree depending on dielectric type.

 

With the TL431 electret booster as published in Elektor a few years ago, I included the current draw of the electret capsule in the overall setup. Initially I included a 47k pot as the bottom resistor in the DC nfb path so the output operating point could be set just so.

With DC coupling between the capsule and TL431 - its as good as it gets. Any DC blocking/coupling capacitor will have a tradeoff between size/cost and low frequency roll off. Most audiophools claim that coupling capacitors taint the audio to a greater or lesser degree depending on dielectric type.

I saw many simple mic preamp, but they didn't use any capacitor for decoupling, someday I will try the difference between added or not added the decoupling capacitor, I'm curious for the components working the purpose out of the normal status, like as 555 and LM317 working as a amplifier.

 

I saw many simple mic preamp, but they didn't use any capacitor for decoupling, someday I will try the difference between added or not added the decoupling capacitor, I'm curious for the components working the purpose out of the normal status, like as 555 and LM317 working as a amplifier.

Its not always that easy - when a TL431 is set up correctly, the voltage on the IN pin just happens to be about right to bias an electret capsule.

In days of old it was a common trick to avoid a separate bias supply (and transformer) for a carbon granule mic by putting it in the cathode circuit of a grounded grid input stage.

The opportunity doesn't always present itself, but usually there's little or no down side when it does.

 

...The easy one is to keep the original circuit and only adding 2N3904 and 2N3906 and 10uf ~47uF output capacitor.

Scott,
You mean something like this:

And 10uf ~47uF cap instead of that 100uf/25v. am I right?

 

Scott,
You mean something like this:

And 10uf ~47uF cap instead of that 100uf/25v. am I right?

That'll have pretty nasty crossover distortion with no bias diodes between the bases.

I've seen examples of unbiased complementary emitter follower pairs driven by an op-amp, they include the output transistors in the nfb loop - I've never tried it to see if it actually works.

 

Scott,
You mean something like this:

And 10uf ~47uF cap instead of that 100uf/25v. am I right?

The output capacitor is depends on your speaker, I think your speaker is too small, so change it to a bigger is better, the TL431 is not like other amplifier IC that they have two sides driver, TL431 just like an npn bjt, and the internal structure issue, when you change the output resistor and it will affecting the input side, but in this simple way, you need to adjust the R11, if the sound still can't make it louder, and the quality is too bad, then you should change to another bigger speaker and build a more components similar as your previous one, the last two circuits in -- TL431 Shunt regulator.

 

The output capacitor is depends on your speaker, I think your speaker is too small, so change it to a bigger is better, the TL431 is not like other amplifier IC that they have two sides driver, TL431 just like an npn bjt, and the internal structure issue, when you change the output resistor and it will affecting the input side, but in this simple way, you need to adjust the R11, if the sound still can't make it louder, and the quality is too bad, then you should change to another bigger speaker and build a more components similar as your previous one, the last two circuits in -- TL431 Shunt regulator.

Something like what?! - that's just another copy of the previous schematic.

The complementary pair of emitter followers are a voltage follower (give or take a Vbe). You simply use the node where the 2 emitters join as the source of nfb for the TL431 instead of from its cathode.

I've never tried the op-amp example - and I don't know if it'll work with a TL431 either.

 

Something like what?! - that's just another copy of the previous schematic.

The complementary pair of emitter followers are a voltage follower (give or take a Vbe). You simply use the node where the 2 emitters join as the source of nfb for the TL431 instead of from its cathode.

I've never tried the op-amp example - and I don't know if it'll work with a TL431 either.

The simple totem pole used with op amp and 555 is ok, but using with TL431 is a challenge, if it want to be simple, that is simple, otherwise using the normal amlifier, the sound is better than other simple circuit, if using this kind of amplifier, but didn't change the speaker to more bigger then it is waste the amplifier.

The source of circuit.

 

The simple totem pole used with op amp and 555 is ok, but using with TL431 is a challenge, if it want to be simple, that is simple, otherwise using the normal amlifier, the sound is better than other simple circuit, if using this kind of amplifier, but didn't change the speaker to more bigger then it is waste the amplifier.

The source of circuit.

<despair!>.

 

<despair!>.

Ok, now is your turn ...
TL431 plus a simple amplifier with a small speaker, louder and good sound ... ?

 

Ok, now is your turn ...
TL431 plus a simple amplifier with a small speaker, louder and good sound ... ?

I've outline how to do it several times - you keep doing something else!

 

I've outline how to do it several times - you keep doing something else!

I have had a small 8Ω/0.25W speaker similar as the PS have, I tested the sound, that is not for the normal music speaker, I bought that to test the small sound or small amplifier, sometimes I used it to hear the voice from NE555, or a small sound through simple totem pole.

 

How about to put this circuit at the first stage to amplify the output of the Mic?

 

In this case it is better to use a transistor PNP. Less interference will affect the power supply.
Example:

 

In this case it is better to use a transistor PNP. Less interference will affect the power supply.
Example:

View attachment 94085

Didn't make any change.(or appreciable change)

 

Hi again guys
I was thinking about designing another amplifier for these mic and speaker that we were talking about here. any simple and cheap circuit?(I think a circuit with about 250-300 gain would be appropriate) for example what's your opinion about a non-inverting with LM358?

 

Hi again guys
I was thinking about designing another amplifier for these mic and speaker that we were talking about here. any simple and cheap circuit?(I think a circuit with about 250-300 gain would be appropriate) for example what's your opinion about a non-inverting with LM358

You should concern are how many volts of In/Out and then decide how high of the gain to reach the output volts, with your gain 300 that it can be using two stages of op amp and to setting the gain as 60 and 5 .

 

I eat my words. I want to use my previous circuit. with TL431
A question: How can I make my circuit more sensitive? currently I should speak at the mic as close as possible to get output from speaker but I would like to get output when I'm not close to the mic.

 

The circuit in your posted #73, you can adjust the R2 to adjust the sensitive, you can also adjust the R3, but you only can adjust a little bit range.

Op-Amp Microphone Preamp, using the specific IC is better, but you also can using LM358 to do the experiment.

 

I need to clarify objectives. What is the voltage? What a load? Battery power or not? Whether the economy?