Wireless Troubles...

[Dave Eason]

Hi there,

I finally finished the wireless project, but the sound is terrible, I'm not sure if any of you guys could make suggestions?  The guitar goes through a simple inverting op amp where the gain can be attenuated.  The signal then goes into an NE571 compressor circuit with pre emphasis.  This then runs through a cmos switch into a Linx HP3 transmitter.  The channel switching of the Transmitter and the audio muting is all controlled by a PIC16F877.  This part works well, I'm happy with it anyway.

But the problem is at the receiver.  The received signal is low - pass filtered at 15kHz and buffered, before going into an NE571 expander circuit.  It is then put through an inverting op-amp where you can increase output gain if you need to.  Here is a diagram:



I think the order of the parts is the most important factor, getting gain and impedance between stages correct and so on.  Any suggestions would be much appreciated!  It's very weak, hissy and distorted at present,  i thought filtering it would improve it, but the butterworth low pass seems to make it worse.

[Dave Eason]

bump