So I want to make an audio amp like this one.
http://www.allaboutcircuits.com/vol_3/chpt_4/5.html
Not those same values of course. In fact here is the circuit I did.
Ok the microphone does not put out 1.5 volts like in the picture in AAC. I used 0.2 Volts as a made up example. (took the mic out of a telephone, checked that it works) The output of a microphone without an amplifier is millivolts or less isn't it?
I notice that when I close the switch, the speaker does emit a crackling sound at the moment of connection and the diaphragm physically moves, i.e. there is a current in the collector. I double checked that by using an LED. My circuit is correct.
But alas I do not hear my voice, or heck not even noise, nothing at all from the speaker but silence. I tried yelling into the mic and even gently tapping the diaphragm. Nothing. Silence....
As you see I biased the transistor like this, the way its connected its the sound signal plus the 561.92mV which comes from my connection to the collector node. So If I assume that the output of the microphone is 0.2 volts (hypothetically) then the transistor never leaves active mode as my simulator says.
Now of course it might not be biased properly because I have no clue what the peak voltage output of the microphone really is, and my meter does not pick up something that small.
So can anyone help?
This is a great example of a real life use of a BJT amp. I want to make an intercom system with this and have it go to my basement. (just a joke, I am just learning the basics of transistors here, if I heard ANYTHING I would be happy)

http://www.allaboutcircuits.com/vol_3/chpt_4/5.html
Not those same values of course. In fact here is the circuit I did.

Ok the microphone does not put out 1.5 volts like in the picture in AAC. I used 0.2 Volts as a made up example. (took the mic out of a telephone, checked that it works) The output of a microphone without an amplifier is millivolts or less isn't it?
I notice that when I close the switch, the speaker does emit a crackling sound at the moment of connection and the diaphragm physically moves, i.e. there is a current in the collector. I double checked that by using an LED. My circuit is correct.
But alas I do not hear my voice, or heck not even noise, nothing at all from the speaker but silence. I tried yelling into the mic and even gently tapping the diaphragm. Nothing. Silence....
As you see I biased the transistor like this, the way its connected its the sound signal plus the 561.92mV which comes from my connection to the collector node. So If I assume that the output of the microphone is 0.2 volts (hypothetically) then the transistor never leaves active mode as my simulator says.
Now of course it might not be biased properly because I have no clue what the peak voltage output of the microphone really is, and my meter does not pick up something that small.
So can anyone help?
This is a great example of a real life use of a BJT amp. I want to make an intercom system with this and have it go to my basement. (just a joke, I am just learning the basics of transistors here, if I heard ANYTHING I would be happy)
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