muragavino

Thanks Hero999, I will order some FETs like the above mentioned 2N5457 or 2N5484 and give it a try as soon as I have the parts. The results I will publish here. Thank you all for your help, it is great to meet you guys!

Thank you very much, audioguru, for your advise and detailed information. These two schematics posted by audioguru, work both with 9V. Could they work with 3.3V? What I need is a circuit to work with the 3.3V you can get out of a PC-mic input, where the tip of the phone jack caries the audio signal, the ring is connected via a resistor of 2.2k to 3.3V, and the sleeve goes to GND. Since the preamps in the PCs do always have a decoupling cap, ring and tip can safely be shorted to supply the 3.3V as phantom power. Thanks again! ,

I just copied it from the PCB that was in the throat-mic housing. It is a single layer PCB and simple enough not to make any error.

Hi audioguru, thanks for the fast reply! The pickup is a simple piezo-disc (buzzer) used in a very cheap throat microphone. Since it wasn´t doing its job - sound was heard from all directions, not only from the throat - I have meliorated the throat-mic by acoustic means using silicon gel as sound conductor and expanded rubber as isolator. Now it works just lovely! As a matter of fact, it works that well, that I wanted to make some more on my own account, but I can´t figure out which transistor to use. The "horrible circuit" works actually very well. Searching the internet I now found as possible candidate the 2SC1623-L6, which has "L6" printed on the SOT23 housing, and which is a NPN. Do you think this transistor is possible? Thanks again, Michael

Hi There! Could anybody help me to find a specific transistor for a preamplifier for Piezo pickups? The preamp works with the 3.3V feed out of e.g. a PC mircophone input (Phantom). In the attachment I prepared a schematic of the preamp. Please help me to understand what transitor is used here. Thanks! Unknown FET.pdf