Low frequency Amplifer

[Twodio]

Hey guys.
I'm trying to construct a circuit that can convert litles vibrations into a more higher.
I want to use only one transistor NPN one LED somes resistors, one capacitor, one electreto mic and one speaker.
The problem is when i try put working doesn't happen nothing.
Someone can help me or pass me another way to make.

 

[BobK]

One transistor is unlikely to get you from an electret mic to a speaker. Show us your circuit.

Bob

 

[Twodio]

The schematic of my circuit is one like this

With two NPN transistors and one adapted LED that doesn't disturb the power traffic

 

[(*steve*)]

The comment about the LED doesn't make any sense (especially since there is no LED there).

the 220k resistor should be connected between the base and the +ve terminal of the battery.

This circuit will draw significant power (it's class A) *and* a DC current flows through the speaker (which is generally a bad thing)

edit: google for the LM380 or LM386 (depending on the power you require).

 

[Twodio]

Exist one class B or C ?

 

[BobK]

the 220k resistor should be connected between the base and the +ve terminal of the battery.

.

Not necessarily, the way it is shown, it will have negative feedback to stabilize the bias. Otherwise, an emitter resistor is needed.

Edited to add: I don't think you get anything like 200mV out of an electret mic, more like 5mV. And an electret mic needs a power connection, if it is not built in.

Bob

 

[CDRIVE]

The bias resistor can be split into two resistors with their common node bypassed to gnd with a cap. This maintains bias stability while removing negative signal feedback.

Chris

 

[Twodio]

Thank you everybody that try help me.
I'll try simulate first until get something higher that 250mA and produce some loud.