Hello,
The following schematic is the first stage of a diy electret preamp I've been using. Currently I have a physical switch to turn ON and OFF the bypass capacitor (C1) for extra gain, but I want to replace it for a MOSFET or something else. The physical switch would still be used to feed the MOSFET's gate (12-9v).
Would a single N-Channel MOSFET (M1) be enough and recommended in this case? I've seen normally two MOSFETs are used in a cascade, the sources connected together to avoid the effect of the diode (SSR). But this is really low signal here and my understanding is that the internal diode would only become a problem above the 0.7v or so?
I bread-boarded the schematic and it works, but I don't know if distortion is being introduced. A 2n7002 instead of a BSS138 was used, since LTSpice showed lower RDSon with it.
Does this seem overall appropriate? Or different type of component (ie. JFET) would be needed? Or a different topology? I just want to avoid ICs with multiple analog switches, since the preamps to control are distant from each other on the board and ideally a switching component for each one would be used separately.
Any advice or comments welcome and appreciated!
Regards,
Domingo
The following schematic is the first stage of a diy electret preamp I've been using. Currently I have a physical switch to turn ON and OFF the bypass capacitor (C1) for extra gain, but I want to replace it for a MOSFET or something else. The physical switch would still be used to feed the MOSFET's gate (12-9v).
Would a single N-Channel MOSFET (M1) be enough and recommended in this case? I've seen normally two MOSFETs are used in a cascade, the sources connected together to avoid the effect of the diode (SSR). But this is really low signal here and my understanding is that the internal diode would only become a problem above the 0.7v or so?
I bread-boarded the schematic and it works, but I don't know if distortion is being introduced. A 2n7002 instead of a BSS138 was used, since LTSpice showed lower RDSon with it.
Does this seem overall appropriate? Or different type of component (ie. JFET) would be needed? Or a different topology? I just want to avoid ICs with multiple analog switches, since the preamps to control are distant from each other on the board and ideally a switching component for each one would be used separately.
Any advice or comments welcome and appreciated!
Regards,
Domingo
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