Hi all, I've a problem using the Atmel u2270b, its a RFID front end chip that interfaces with a PIC to read FDX transponders (they load the field generated by the chip and coil) I've got it reading ok but recently found a aplication note on how to increase read range by putting a op amp infront of the u2270b. My knowledge of opamps is very little but I set about it and built up a board to test things out. To start with nothing happend, that is until I touched the legs of c3 with my finger, hey presto it reads?? The only difference in my setup is the data rate of the transponders is f/32 rather than f/64 which is described in the application note (which hopefully is attached) Does anyone have any ideas about how to calculate the right capacitors to use? I guess I'm changing the capacitance by touching the legs? Any help would me welcome. Thanks Geoff Ps I have c3 and c4 on a breadboard and all the rest on a homemade doubleside pcb.