TL072 question

[tungngruv]

I changed the pinout of my op amp socket to replace the LM741 with the TL072 op amp ( lug 6 to lug 1, lug 7 to lug and the circuit does work BUT.... I'm getting a real high pitched "squeeling" in the back ground and get this, it goes away when I put my fingers close to it while trying out different op amps.?? It's in the "Simple Octave Up" circuit and it also slightly affects my Multi Fuzz sound, although the fuzz sound returns to normal if there is no op amp socketed in the Octave. They are both in the same enclosure and yes, it worked fine with the 741 (but I just had to try and make it better)!! Did I miss something as far as the op-amp pin out? Thanks for any help.   :lol:

[tungngruv]

Above should read: lug 6 to lug 1, lug 7 to lug 8.

[David]

You have just replaced a single op-amp with a dual.  The pin-outs are not the same at all...

I would recommend a TL071 or a 5534.

[Paul Perry (Frostwave)]

The TL072 has much higher bandwidth and gain that tne old 741, so any loose or unshielded wiring (especially inputs and outputs) is much likelier to cause local oscillations.
Replacing a single op amp by a dual isn't a problem, I proto with duals & quads (never know when you will need another 3 op amps, right?).

[petemoore]

Here's what I did...I was gonna mention this, but it's 'unruly'...
 Took an 8 Pin IC socket.
 Stuck it in a small piece of perf, ran solid core wires from the socket pins/padholes.
  Took another small piece of perf...[if you left the wires long enough in step 2] and  'wrangled' the pinout of a dual, into one of a single...making a dual OA to single OA 'conversion socket'...this was any single OA builds I wanna try A dual in, I can just use the converter socket.
 Thing is If I were to leave it in, I'd solder a leg or two down, and this would ruin the circuits socket for swapping in singles.
 I've built the SOU, and the mojo of Opamp lores might be harder to detect with all that wave rectifying going on in there...the 741's 'pecularities' might be part of the mojo for the SOU...

[mikeb]

Paul hit the nail on the head - and it sounds like the extra little bit of capacitance provided by your hand is enough to cut out the squeal. If this is the case, you can put in a permanent 'hand' by placing a 5 or so pf cap across the feedback loop resistor (I'm assuming there is one if you have gain   from this cricuit - I haven't seen the schematic).

Mike