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Yeah, no kidding. I hope I didn't waste anyone's time. With a bit of luck, this thread will appear when someone else has a similar problem and will give them some insight.

mike

Problem resolved. When I originally placed the op amps, I didn't have any sockets, so I soldered straight to the board. When I replaced IC4 and IC5 I did so without desoldering the pots first. It was an awkward angle to work at and I left a very tiny bridge between pins 1 and 2 of IC5. Since the inverting input, pin 2, was held low, the voltage would never rise as the capacitor (C10) charged (and the capacitor never was able to charge because pin 2 was low) and thus the op amp output never switched from one voltage rail to the other.

Lessons learned:
1) Digikey is not infallible
2) Don't try to cut corners and solder under other components - a couple minutes to desolder and later resolder the blocking component is less than the debugging time when you end up doing a half-assed job

mike

Well, I found one problem. I didn't check the resistor multipliers well enough. R30, which is 47k, was 47R. This brings my non-inverting IC5 input (pin 3) up to 5.433V. Still no oscillation, though.

The resistor mix-up is sort of interesting, as I've never purchased any 47 ohm resistors. Yes, after checking my bin, I have 25 of them, including the one I mistakenly used. I also have a Digikey part label in my box saying I ordered 25 47k resistors from them. Looks like they made a picking error. I've never had a problem with Digikey before (and I've orders lots of components from them for both my job and pedal stuff), but I think I'm going to start spot-checking my receivables.

I still have some error with my circuit and if anyone has reference voltages, I'd be very grateful.

Thanks,
mike

While the envelope-follower part of the sharkfin works, I'm having problems with the FSH section. In particular, my low frequency oscillator isn't oscillating. Or at least the LED isn't switching on/off. That's driven from the LFO, correct?

I've verified my resistors and swapped out IC4, IC5 and Q4, but the behavior didn't change.

Here are voltages on the IC4/IC5 pins:
IC4:
    1    -8.75
    2    0.003
    3    0
    4    -8.76
    5    -8.75
    6    0.073
    7    9.12
    8    0

IC5:
    1    -5.655
    2    -5.655
    3    0.017
    4    -8.76
    5    -8.08
    6    7.95
    7    9.12
    8    0.005

Can someone provide some reference voltages for me, or even better, suggest a possible failure reason.

Thanks,
mike

I think I've got the noise about as low as I can get it. It's still higher than I'd like, but better than before.

This link, http://brettcave.net/howto/circuits/PowerSupply_DualRail-LT1054-Boosted.pdf, shows an example using the LT1054 as a dual rail, regulated doubler. Most of it isn't needed for this application, but I think Rpf would help reduce noise. We can't really add it to this board without changing the layout, though. The 18V current doesn't really flow out of C19 in this layout. Topologically it is equivalent, but there's not really a path from D13 to C19 and then to the rest of the board. D13 goes to the 18V rail and C19 also sits on the rail, but a bit distant. There's no way easy way to squeeze a small resistor between D13 and C19+. R42 does help clean up the 10V and 5V rails.

So, for other people who've found this thread and are experiencing noise like I was, add 0.1uF (100nF) caps between the power and ground on each of the ICs (except IC6 - the LT1054). Use small ceramic caps and have them straddle the ICs. Solder the cap leads directly to the IC pins. If you take a little care, you'll still be able to remove the ICs from the sockets with the caps attached to the IC.

I also swapped C19 and C20 again. It makes more sense to me to have the larger cap closer to the LT1054. I also added 0.1uF caps across C19, C20 and C17. I put those on the bottom of the board, soldered directly to the larger caps' terminals. Again, use small ceramics that can lie flat against the PCB. I'm not sure these changes added anything, though.

Yeah, I'm a digital guy. You wouldn't guess from all my questions, but I do hardware and software for embedded systems. You put 0.1uF caps on every IC. You don't really think about it. You push them off the the side of the schematic so they don't clutter things up, but they're there.

I've still got some noise, but I think I'm headed in the right direction.

I'm think I'm onto something. I just realized none of the op amps have decoupling caps. There are the really large 10uF and 100uF tank caps, but there aren't any small caps at the power pins of the ICs to handle the short, transient loads. I added some 0.1uF caps to the power pins of the op amps and it definitely helped. There's still some noise left, though. I haven't added any to the CA3080's so that's next. I might also add a 1uF cap on the 18V for medium transients.

I did have R5 at 330k, a change recommended in the build notes, but after trying the 180k from the schematic, I did not see an improvement. I've got R21 at the recommended 2k.

I keep coming back to the power supply. If I look at both ends of R42, one side is the 18V supply and the other is the 10V supply. The 10V side is clean. The 18V side is noisy. This is when I'm powering the circuit with a 9V battery, so the noise is not coming from the external power. In fact, noise is being coupled on to the 9V terminal of the battery. The noise is not present when I check the battery on its own. Only when it is attached to the circuit.

When I use the FFT function of the scope, I see a number of harmonics that vary according to the rotary knob setting, but there are two large peaks that are present all the time. One peak is at about 5.2k and the other is around 8.3k - give or take.

I might experiment later with sourcing 18V from my bench supply directly to 18V rail and see if that makes a difference.

Here's a link to photos of the top and bottom. Note, the tank caps are still reversed and I haven't removed the sockets yet.

https://www.icloud.com/photostream/#A3JtdOXmJt1qxk

I had high hopes that buttoning up the board would sweep the problem under the rug, but it didn't help. Alas. The rotary and pots are soldered to the board. I tried grounding the input on the board and the noise is still present, so I don't think I 1k on the input will help. For the same reason, I'm not sure shielded hookup wire will help either.

If I step back a bit and look at the big picture, I get a high pitched noise, almost a sinusoid, on the output even when the input is grounded. The noise character changes with the rotary switch, being most noticeable in position 1. Position 3 is the least noticeable. The noise does not change with the sweep pot. When I attach a guitar and play a little, the noise changes with the envelope. If I play a note and then stop, the noise starts out low and then slowly rises in pitch.

Smaller picture, if I use the audio probe and trace from the input, the first place I hear noise is on pin 8 of IC1. It is a wideband noise. There is also some noise on IC4, pins 1 (low pitch, faint) and 7 (high pitch, louder). On IC5, I have noise on three of the outputs, 1, 7 and 14, not 8 though. Pins 1 and 14 sound the same, a high pitch, sinusoid type noise with pin 1 being louder. Pin 7 is a middle freq sinusoid type noise. I think the noise on IC4 is coming from the noise on IC5. I don't know where the IC5 noise is originating.

I would consider the level of noise on the output unacceptable, and aside from one other person that was able to fix their problem by replacing their CA3080's, I haven't seen any complaints about this board, so I'm pretty sure the problem is with my build, not the design. I must have a bad solder, a bad component or I miss-stuffed a component.

As per the build instructions, I do have a few socketed discretes. I haven't detected any noise on them, but maybe it'll help if I remove the sockets. I'll also swap back C19 and C20.

The bench supply didn't help. It's a linear, non-switching regulator and with a clean output, so while there might be noise coming from my 9V wall wart, I don't think it is the root cause. If that was the main issue, using the bench supply should have fixed the problem.

Probing from the input side of things, I found a lot of noise on pin 8 of IC1. In fact, for a little while I could hear voices in the noise. So either, I need to double-check what I ate for lunch, or it's picking up AM radio.

I'm beginning to think that this is just a noisy circuit. Maybe the noise I'm hearing is to be expected. I did notice that when the rotary switch is in position 1, contact B is left floating and I get a lot of noise going into pin 3 of IC5A. Shouldn't pin 5 of the rotary switch be connected somewhere? It is an input to IC5B, after all.

You asked if the board is in an enclosure. Yes, sort of, not really. It is wired into an enclosure, but I have the back off and the wiring on the board allows it to hinge up so I can get at both sides. So, effectively, it's not really in the enclosure.

Thank you, I really appreciate the help you've provided. I'll continue to detail what I find in case other people have a similar problem and their searches bring them here. Hopefully, there will be a resolution at the end of all this.

Yes, the rotary switch does affect the noise. I'd been testing with it in the 1 position, but now that I've moved it, I see there is noise on pin 1 as well as pin 7, it's just not very noticeable when the switch is in the first position. Here's how I'd characterize the noise.

Pin 7
switch 1  high pitch
switch 2  mid
switch 3  none (or very faint)
switch 4  same as switch 2

Pin 1
switch 1  none (or very faint)
switch 2  low-mid
switch 3  faint mid
switch 4  same as switch 2

An LM833 op amp didn't improve things.

When I was probing this last go-around, I noticed the noise was much more pronounced if I accidentally brushed my hand against the circuit input. Presumably, I'm bringing in noise which is being processed and amplified. Maybe the circuit is working as it should and I'm just not filtering external noise as well as I should be.

And now I'm back to the power supply.

I'm not sure I had my scope AC coupled last night. Now I do and I see 7kHz (and 14kHz - the scope has some basic FFT capabilities) on the 9V input. I also see this on the 18V supply, but not so much on the 10V. I'll hook this up to a bench supply tomorrow and see if that makes a difference. If I understand the LT1054 configuration, it isn't really regulating the input voltage, it is just doubling it. I don't see any low-pass filtering on the 9V input either. Will any noise on the supply voltage get passed through to the 18V supply? I should also point out that I still have C19 and C20 swapped. On my board, the 18V supply has the 100uF cap while the 5V supply has the 10uF cap. If the bench supply helps, I'm thinking I can get by with a very low value resistor on the 9V input in conjunction with the existing 100uF cap, C17,  and still filter out the 7kHz component from my wall wart.

I've done some more experimenting. I swapped the LT1054, added a 15pF cap across pins 2 and 7 (had to use an 0402 surface mount as I didn't have any through-holes that low) and swapped the 18V and 5V tank caps. None of those changes really helped. I looked at the signal with a scope and did see some noise, but it was about 35kHz. At this point, I figured I probably screwed up when I was tracing the source of the noise and started afresh.

On my second go-around, I have traced the noise to pin 7 of IC4. The signal that connects C6, R16, R17 and the output of the op amp has significant noise. This noise is attenuated on the other side of R17 (towards the circuit output), but is still present enough to be heard. I don't hear it on the other side of C6 or R16.

I tried swapping the JRC4558 with a different one, but it didn't help. I couldn't hear anything on either of the op amp's inputs. There still might be something on the op amp power, but if there is, it is pretty faint. The other op amp in the same package is clean.

I did try swapping out the CA3080's (sourced from Small Bear). I've got some NTE996's showing up today or tomorrow and I'll swap those in when they arrive.

Thanks for the advice. What you say makes sense. I'll try swapping the LT1054. TI's LT1054 datasheet says the output ripple is proportional to current load, so if IC5 is drawing current, the ripple will increase when it is present and decrease when it is removed. Once I determined that removing IC6 reduced the noise, I didn't test removing IC1 to see if it also reduced the noise. According to the datasheet, it looks like replacing C19 with a larger value might help too. The +5V rail has a 100uF cap. Perhaps I should swap C19 (18V rail, 10uF) with C20 (5V rail, 100uF).

I have built a Honey Dripper and while it basically works, I get a soft whistling sound on the output. This occurs even without an input. I'm hoping someone can offer some advice and help me track down the problem.

Using an audio probe and working backwards from the output, I traced the problem to high frequency (audio high, not RF high) noise on the 18V rail. By removing ICs one at a time, I was further able to track down the source of the noise to IC5 pin 4. If I remove IC5 from its socket, I don't hear any noise on the 18V signal. With IC5 socketed, I hear a high pitched noise. I swapped out IC5 with another LM324, but it didn't help. I've also touched up all my solder joints and I did't see any obvious shorts or opens.

I used the audio probe to check the other pins on IC5. I hear the same type of noise, though sometimes at different frequencies or amplitudes on pins 1, 2, 4 and 14. On pins 3 and 6 I hear more of a white noise type of noise. The other pins are quiet.

Here are some voltages:
18V rail -> 16.23V
10V rail -> 9.46V

IC5 socketed:
1  4.75
2  4.75
3  4.40
4  16.21
5  4.55
6  4.75
7  4.41
8  2.19
9  2.60
10  2.60
11  0
12  2.60
13  2.60
14  0.42

I also checked the voltages with IC5 removed from the socket
1  0
2  0
3  7.03
4  16.48
5  4.56
6  6.53
7  6.77
8  0
9  0
10  2.60
11  0
12  2.60
13  0
14  0

Any advice on what might be going on or where I should check next would be greatly appreciated.

Thanks,
mike