...and then all of a sudden, it all went to hell!

[ExpAnonColin]

   

Last night, at around 11pm, I was working on my tremolo design... namely the envelope control.  I had the tremolo working just fine, it's astable multivibrator LDR based.  Working quite well.  Then, I start working on my 386 based envelope control for the speed. When I first put it together, I had the standard configuration for high gain (2 and 4 to ground, 1 and 8 connected, input to 3, output from 5, Vs to 6) with the output going into a 1uf cap and then into the + side of the LED, the other to ground.  First, it worked so that the light was always on and when I strummed it got a tiny bit dimmer.  Then, all of a sudden, the LED stopped being always on, and instead got brighter when I strummed.  "OK", I said, "No biggy.  Must have been a bad connetion.  I'll just design the circuit around this".

About 30 minutes later, the LED stopped working.  No nada.  The LED worked just fine when connected to a + voltage and the - side to negative, and the LM386 was sure as heck still amplifying the signal... but something was different, and it was no good.  That was when I noticed the high pitched squealing...

For some reason, after it stopped working, it started squealing, even without the amp plugged in.  It only squealed when my hand was near the capacitor, and I'm assuming it was emitting waveforms through the air and the guitar cable plugged into my amp was picking them up.  But why was it squealing?  I figured it MUST be a bad battery, or even a bad op amp.  So I replaced the battery.  Put a DC jack on there, even.  No cigar.  So I replaced the 386.  No cigar.  So I moved the whole assembly on the breadboard in case there was a bad trace somewhere on there.  NO CIGAR.  I replaced EVERY component in the circuit.  NO CIGAR!  Tried bypassing the internal gain control with capacitors instead of simply connecting them... no cigar.  When I put the output of the circuit into the amp, I definitely got the high pitched sqealing, into the amp now, and in unison with my guitar.  It sort of produced this terrible high pitched distortion.  When I moved my hand around the circuit, the pitch changed.  When I connected pin 8 to a 10uf cap, and the other end to nothing, I get the radio.

So, obviously things are really messed up.

Now, it gets worse.

Since the only way the envelope control and the astable vibrator are connected is the Vs (at the moment), I thought I'd try the vibrator today to see if it was working.  Yep, working just fine.  Then, again, all of a sudden, kaput.  The LED stopped blinking.  Again, I try replacing the LED, etc etc etc.  STILL nothing.  Battery, everything.

So I've tried the following:

-Moving parts on breadboard
-All new parts
-Different voltage sources (batteries and wall)
-Different breadboards (yeah, I moved the entire envelope control to another breadboard.  Nope!)

And just about EVERYTHING I could think of.  Honestly, I'm totally befuddled.  

Someone, please please please help me.      

-Colin