Please help me to wire up a sensitive audio driven trasitor led circuit. I have used the one shown but a transistor circuit should draw less current.

 

Can't you just increase the size of the resistor?

 

There are three resistors in this circuit but that doesn't matter. I had tried many times to wire up an LED driver circuit using only one or two transistors but never had luck. This circuit that I found on the web does work but I feel strongly that a transistor should be able to do the same thing- make a LED flash along with a low level audio signal. A dynamic microphone, for example. I really wish that I could figure out why I am having so much trouble in getting a simple transistor driven LED circuit to work. Thanks for any help you can give to me.

 

There are three resistors in this circuit but that doesn't matter. I had tried many times to wire up an LED driver circuit using only one or two transistors but never had luck. This circuit that I found on the web does work but I feel strongly that a transistor should be able to do the same thing- make a LED flash along with a low level audio signal. A dynamic microphone, for example. I really wish that I could figure out why I am having so much trouble in getting a simple transistor driven LED circuit to work. Thanks for any help you can give to me.

Post a schematic.

 

There are three resistors in this circuit but that doesn't matter. I had tried many times to wire up an LED driver circuit using only one or two transistors but never had luck. This circuit that I found on the web does work but I feel strongly that a transistor should be able to do the same thing- make a LED flash along with a low level audio signal. A dynamic microphone, for example. I really wish that I could figure out why I am having so much trouble in getting a simple transistor driven LED circuit to work. Thanks for any help you can give to me.

For normal sound levels, the output of a dynamic microphone is only 2 or 3 mV. You would need a gain of several thousand to turn that into a LED signal. The output of an electret microphone is anywhere from 10 to 100 mV depending on the type.

 

Please help me to wire up a sensitive audio driven transistor led circuit. I have used the one shown but a transistor circuit should draw less current.

Do you want the LED to stay on fully when audio is detected?

 

There are three resistors in this circuit but that doesn't matter. I had tried many times to wire up an LED driver circuit using only one or two transistors but never had luck. This circuit that I found on the web does work but I feel strongly that a transistor should be able to do the same thing- make a LED flash along with a low level audio signal. A dynamic microphone, for example. I really wish that I could figure out why I am having so much trouble in getting a simple transistor driven LED circuit to work. Thanks for any help you can give to me.

Forget the other two resistors, just reduce the 100Ω resistor that connects the LED to the battery. That will reduce the current in the LED. It may or may not produce the effect you are looking for. BTW I have NEVER seen anybody try to drive an LED through a capacitor. That might be a contributing factor to your difficulties. I guess there must be a first time for everything.

It just might help if you tell us what you are trying to do instead of telling us how you want to implement a solution. You seem to have some notions that are not feasible.

 

Please update your question. It is not clear what you want to achieve. Do you want the LED to flash when audio is above a certain loudness? Do you want the LED to stay lit continuously while audio is present? Other?

The LM386 is not a transistor. Do you want a different circuit that uses only transistors?

ak

 

First off-this circuit above is what I found on the web. It DOES work. Forget about that circuit. I am in search of a circuit that uses transistors only that will drive an LED anytime there is audio spoken into a dynamic microphone.

 

First off-this circuit above is what I found on the web. It DOES work. Forget about that circuit. I am in search of a circuit that uses transistors only that will drive an LED anytime there is audio spoken into a dynamic microphone.

Try this circuit, only 0.5 ma on standby.

 

Post a schematic.

The schematic IS posted in post #1.

 

Your LM386 amplifier has problems:

 

Your LM386 amplifier has problems:

(Whine Warning) BUT, BUT -- it workssss!!!

 

It works BUT its idle current is too high, maybe because of the missing parts.

 

It works BUT its idle current is too high, maybe because of the missing parts.

Maybe read post #9.

 

The LM386 circuit originally posted also needs a resistor from the input to common, in addition to the other parts required. At least 10K oms.

 

The LM386 circuit originally posted also needs a resistor from the input to common, in addition to the other parts required. At least 10K oms.

According to the front page of the datasheet, that resistor (50K) is built into the chip for both inputs.

ak

 

OK, I neglected to consult the data sheet. I recall that issue with a different amplifier IC.

 

The schematic IS posted in post #1.

That is the schematic he tried, it works, and he rejected because it’s quiescent current is too high.

I was asking for the transistor circuit that he could not get to work.