Hi guys!
Hope you're havenig a nice weekend.
I'm working on a new pedal and I've designed a very simple stage with a J201 in a SOT23 package.
As you can see in the schematic it's pretty straightforward and it sounds very good, when it's working
buffer1.png
It worked on the breadboard and I've ordered some PCBs from a factory, made with eagle and tested so I'm pretty sure about the board quality.
The thing is: when I connect everything and plug my guitar or a signal generator I got nothing on the speaker or the oscilloscope. While checking the connections I thouched the tranny and it started working. Disconnected and connected again and it kept working. Disconnected for a while this time and connected again, not working. So I touched the transistor again and magic! It works!
I've resoldered it again, double-checked connection but nothing, it always needed the finger magic to start doing is job. So I tried to look closer while I was touching it and discovered that what my finger was doing was connecting the D and G pin of the J201. So I tried with a piece of wire and yes, finger magic was now wire-magic. The weird thing is that I dont need to keep touching it, just a brief connection of less than a second.
Guys can you explain to me what was happening and why the J201 need that to start working? After that brief connection with the finger or the wire it goes on without any trouble at all.
Hope you're havenig a nice weekend.
I'm working on a new pedal and I've designed a very simple stage with a J201 in a SOT23 package.
As you can see in the schematic it's pretty straightforward and it sounds very good, when it's working
buffer1.png
It worked on the breadboard and I've ordered some PCBs from a factory, made with eagle and tested so I'm pretty sure about the board quality.
The thing is: when I connect everything and plug my guitar or a signal generator I got nothing on the speaker or the oscilloscope. While checking the connections I thouched the tranny and it started working. Disconnected and connected again and it kept working. Disconnected for a while this time and connected again, not working. So I touched the transistor again and magic! It works!
I've resoldered it again, double-checked connection but nothing, it always needed the finger magic to start doing is job. So I tried to look closer while I was touching it and discovered that what my finger was doing was connecting the D and G pin of the J201. So I tried with a piece of wire and yes, finger magic was now wire-magic. The weird thing is that I dont need to keep touching it, just a brief connection of less than a second.
Guys can you explain to me what was happening and why the J201 need that to start working? After that brief connection with the finger or the wire it goes on without any trouble at all.