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Maybe you can help,
On the circuit there is a 2R2 resistor on the source of the fet... WHY? what voltages does it see? which currents flow through it... how would its size be determined, if I change bias etc in the circuit...
From what I see the 100k pot sets up a voltage divider to provide x volts DC on the gate to enable the fet to conduct from drain to source...
The signal in AC is also put to the gate and a small AC portion is added to the Drain which is allready at a potential of 6.45VDC in order to reach the 168mA,DC on the drain resistor.
At the point between the resistor and drain, I can only see how a small fraction of the signal voltage gets here... Does this small bit also flow trough the Drain to source?
How do I calculate voltage/current gain?
Where is the amplification? what am I missing?
Uncle Nelson, how about a low voltage zen headphone tutorial...aimed at the beginner... In the attached circuit the only part that gets realy hot 60+C is the 2W resistor, I used reasonbly small sinks on the fets themselves. So its a very cheap/safe/easy intro into the wonderfull world and sound of Mosfets.
Curse at the devil over your coffee, and he posts in your thread...
Nelson, if it wasn't for this little amp, I would not believe myself capable of building one of your amps...
I am now a student of your school.
I see some of your circuits do connect to ground there but seems to have some gain setting method through a trimpot over input and output caps.
Actualy I think I'm makeing progress trying to design another version with double the supply voltage etc... to test if I got the fundemental concepts....
PS, if the 2R2 =33R would it mean unity voltage gain?
First goal is to go from 168mA bias to 400mA wich represents 4.8Watt dissipation over the drain resistor of 30R. with 24v supply, I should be looking at 12V on the drain?
No idea what the fet would be dissipateing...I will hide behind a cushion (the only word ohter than fashion to end on -shion). The current circuit suggests it would be less than the Resistor.
Nelson, if it wasn't for this little amp, I would not believe myself capable of building one of your amps...
I am now a student of your school.
I see some of your circuits do connect to ground there but seems to have some gain setting method through a trimpot over input and output caps.
Actualy I think I'm makeing progress trying to design another version with double the supply voltage etc... to test if I got the fundemental concepts....
PS, if the 2R2 =33R would it mean unity voltage gain?
First goal is to go from 168mA bias to 400mA wich represents 4.8Watt dissipation over the drain resistor of 30R. with 24v supply, I should be looking at 12V on the drain?
No idea what the fet would be dissipateing...I will hide behind a cushion (the only word ohter than fashion to end on -shion). The current circuit suggests it would be less than the Resistor.
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