electronic mind said:
hi
this circuit is an audio mixer.... i can beleive that but can someone explain to me how??
i have an idea i hope its right ,,, and if im wrong plz correct me::::
The input node works as a current adder and then the total current is amplified by the transistor
This shows an N-channel JFET. My understanding is this device is not current controlled but voltage controlled Vg-s and is symmetric from D-S.
Since no current flows into the gate, the current flowing in R2 is equal to that of R4. This current is I = (a*Vin1 - b*Vin2)/(R2+R4) where Vin1 and Vin2 are the two inputs respectivly and a & b are scale factors from the input divider network (assuming C coupler is good short).
This current produces a voltage at the gate via the R2 (or R4) drop. This voltage (work the math) will be a scaled sum (or difference) of the two inputs Vin1 & Vin2. Vg = aVin1 - I*R2.
So it does sum the voltages and I suspect that with a properly biased JFET (Doesnt look biased to me) this voltage will be amplified at the output via the source resistor. I'm no expert with mixer circuits, but this seems like a crude circuit.. Someone else on here can likely provide better insight.