Fuzzca, Judging from your measurements it seems to me there may be something screwy going on with the feedback on the second op-amp of IC1 and maybe on the first op-amp of IC2 as well. 2nd op-amp on IC1 behaves like it has a huge amount of gain (like if there were no feedback at all...) and is amplifying its on small error offset voltage -the rising 5V -check to see that the 47nF cap (nF not uF, right?) is really connected to leg 6 and 7 of IC1 and that you get no low ohm reading to GND at any of these points (...power off, reading >10k). Then do a similar check on the feedback chain between leg 1 and 2 on IC2 and check resistance to GND as well. Don't give up...fuzzca wrote:Man, I am having the toughest time trying to get this working!
I started off early in the thread and built a vero layout based on the original schem that Grizzly posted on page 3 of this thread. "Systech_Harmonic_Energizer_CompLayout_and_Schematic_RevB.pdf " All I had on hand was dual opamps so I built around that. I find it's a pretty epic vero build when there are two opamps (I can't believe how compact Grizz's quad layout is!) but I persevered and took my time, things seemed good. Fired her up ... signal passes but not much happening except the gain works a bit. I reevaluated my layout against the schem. Seemed OK. I checked this out several times over the week
Now it was forensic "CSI" time. I went back to the original pics Joe posted, traced them out. Noticed a couple of things. To me it looks like that the 2K2 from the output (pin 1) of the second opamp feeds back to the input(pin 2) of itself, the second opamp, not the first opamp. Additionally it looks to me that the pin 1 on the bandwidth pot doesn't go to ground via 10uF but connects to the first opamp in (pin 2). Aha, I thought, now she will fire right up,... nope, same deal as before, gain works a bit and that's all.
I measured the voltages and they are looking completely f*cked. I might just give up on this tangent. But hopefully I've missed something simple, that would be nice!
If anyone can make sense of this, throw me a life jacket!
Using 9.12 V battery
Power NPN: E-7.3V, B 8V, C - 8.5
Buffer JFET: D-7.3V, G-0V, S-1.4V
IC1: 1-3.6V, 2-3.6V, 3-3.6V, 4-0V, 5-3.6V, 6-3.6V, 7-5 V and rising, 8- 7.3V
IC2: 1-3.3V, 2-3.6V, 3-3.6V, 4-0V, 5-3.6V, 6-3.6V, 7-3.6 V , 8- 7.3V
Sorry to thow this mess into the mix but if someone can spot a fatal flaw I would be all ears.
Cheers
Cheers and Cheer up/ MB