Different ways to amplify a MIC

[L3GACY]

I am amplifying the output of a small mic with a tip31 and using the output on small speakers from old headphones and lighting an LED and I was wondering if there are other ways of amplifying it other then using an LM386, I am still learning about building circuits and I can never get the LM386 to amplify the LED; it just gets DIM.

 

[audioguru]

A single transistor does not have enough voltage gain to amplify a microphone and drive a speaker. It might flash an LED.
An LM386 amplifier can have a voltage gain of 200 and drive a speaker or flash up to 15 pairs of LEDs.

Attach the schematic of your transistor amplifier driving a speaker and driving an LED.
Also attach the schematic of your LM386 circuit driving an LED.
Then we will show you how to fix it.

 

[bychon]

Ways to amplify a microphone include bipolar transistors, j-fets, op amps, and a few I don't know about, like CMOS chips in linear mode and mosfets.

 

[L3GACY]

**broken link removed**

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I hope I did it right on the computer
(I used fritzing)
For the small speaker its pretty much the same except the LED is replaced by the small headphone speaker

 

[audioguru]

You have the battery connected backwards and the LED connected to the base of the transistor which is its input.
Is your mic an electret, dynamic or carbon type?

The LM386 can drive a speaker or it can drive up to 15 pairs of red LEDs like this:

 

[L3GACY]

The box my MIC came in says Condenser Michrophone Element, what would be the proper way of wiring the TIP31 in my situation?

The problem with the LM386 is that im so nooby I cant hook it up right to anything I hooked it up to my LED the other day and all it did was light dimly

I will keep trying though and keep trying I hope I can be as good as you Mr. Audioguru

 

[L3GACY]

**broken link removed**

This is pretty much what I tried building but instead of the earphone plug for input I used my MIC
But I guess its wrong. Is there any way I can use this the right way and amplify it further?

 

[audioguru]

A "condenser" microphone needs a 48V supply voltage. I think you probably have an electret condenser microphone that has the 48V built-into its electret material. It has a Fet transistor inside that needs about 0.5mA through a 10k resistor from about 9V.

I showed you exactly how to hook up an LM386 to an electret mic and to a speaker or to many LEDs.

You show a transistor that is missing bias on its input. It is also missing an input coupling capacitor. Its input might blow up any music source because it is missing a current-limiting resistor.
The output of the transistor is also missing a current-limiting resistor so the LEDs, the transistor or both might blow up.

 

[L3GACY]

What does BIAS mean? and what does the input coupling capacitor do?

 

[audioguru]

What does BIAS mean?

The input of a transistor needs to be biased properly for it to work properly as an amplifier. The base-emitter of a transistor needs a 0.6V to 0.8V bias voltage for it to turn on but the voltage depends on the transistor, its temperature and its current. Your transistor had no bias voltage so instead of being an amplifier it was a rectifier.
The input signal modulates the bias voltage which causes the transistor to turn on more or to turn on less.

what does the input coupling capacitor do?

A coupling capacitor blocks DC but passes AC.

 

[L3GACY]

I hope you don't mind me asking so many questions,
I understand what you are explaining about BIAS but what exactly is it, how can voltage be biased?

 

[audioguru]

I hope you don't mind me asking so many questions,
I understand what you are explaining about BIAS but what exactly is it, how can voltage be biased?

There are many tutorials about transistors and how to use them on the internet.

Here is a transistor preamp circuit. Its base is its input and is biased to a suitable voltage by RB1 and RB2 which are a voltage divider. The input capacitor stops the input source from shorting the base bias voltage.
The collector is the output and has a collector resistor to the positive supply voltage.
The emitter has a resistor to make the base bias voltage work with different transistors (they are different even if they have the same part number) and when the transistor is at different temperatures. The emitter resistor causes the AC voltage gain to be less with reduced distortion and can be bypassed with a capacitor to increase the AC voltage gain.