Moog EM Theremin Power Circuit

Trying to figure out what's going wrong with my power circuit for the theremin described here. Simple circuit that takes 12VAC to make a dual polarity 12VDC supply. The points which should measure +16 and -16 read +-17.5V instead, but I assumed that was because of no load. The positive output generates about 11.8V, which is fine, but the negative output generates -.6V instead of -12. My power supply is a Jameco ADU120200 which is 12VAC and 2A and I'm using one of those little wiring harnesses that plugs on to the adapter. I am absolutely positive that my circuit is correct, I've built it with different organizations, spread out, clumped, on a breadboard, on a prototyping board, all to the same result. What am I doing wrong?? 

I also noticed that the LM78L12 pinout on the schematic from Moog doesn't match the datasheet, IN/OUT are flipped compared to the official datasheet from TI. Didn't try it with Moog's pinout, as I'm fairly certain that would blow up one of those massive 2200uF caps.

"The positive output generates about 11.8V, which is fine, but the negative output generates -.6V instead of -12."  - nato

0.6V is a diode forward voltage, which is probably a clue.

"I also noticed that the LM78L12 pinout on the schematic from Moog doesn't match the datasheet, IN/OUT are flipped compared to the official datasheet from TI."

I don't see pinouts for the regulators on the schematic you provided a link to, but that may be a clue as well.  Also, different packages can have different pinouts.

Roger Hess made an annotated updated schematic, and I've snipped out the power supply section here:

Did you by any chance not notice the negative regulator is a different part number than the positive regulator?  LM79L12 (neg) LM78L12 (pos).

Regulators can oscillate, small capacitors very near the pins are often specified in the spec sheets.  Sometimes they are sensitive to output capacitor ESR and require a higher ESR type, like tantalum.

"The positive output generates about 11.8V, which is fine, but the negative output generates -.6V instead of -12."  - nato0.6V is a diode forward voltage, which is probably a clue."I also noticed that the LM78L12 pinout on the schematic from Moog doesn't match the datasheet, IN/OUT are flipped compared to the official datasheet from TI."I don't see pinouts for the regulators on the schematic you provided a link to, but that may be a clue as well.  Also, different packages can have different pinouts.Roger Hess made an annotated updated schematic, and I've snipped out the power supply section hereid you by any chance not notice the negative regulator is a different part number than the positive regulator?  LM79L12 (neg) LM78L12 (pos).Regulators can oscillate, small capacitors very near the pins are often specified in the spec sheets.  Sometimes they are sensitive to output capacitor ESR and require a higher ESR type, like tantalum.

On the right side of the circuit diagram on pg. 3, you can see an incorrect pinout for the positive regulator. Not sure how the forward voltage helps me, it seems that its just the voltage over that diode D3? I did actually try using the pinout from Moog and it bulged out a capacitor. I do have both the positive (LM78L12) and negative (LM79L12) regulators, I do know they have different part numbers, and I am aware of the different pinouts for different packages - I'm using the TO-92 3-leg. When I breadboard or prototype board the circuit, the ceramic caps are directly next to the regulators, and I follow the advice given on the right side of pg. 4. I think even if I didn't follow that placement advice, I would still get an output voltage that is slightly off of -12V, not -.6V.

I've spent probably 20 hours on just this small circuit and $80 on parts in hopes that ordering new components will make it work. I already have the (very expensive/hard to source) components for everything else, so I'm set in on it now.

Is the max amperage of my AC/AC adapter too high or is there any significance of the +-16V points being at 17.5V instead? Also, in that Etherwave power circuit, why is there another set of ceramic caps, different diodes, and the output caps mismatched in value (4.7 vs .1u)? Why/how would that change the behavior of the circuit? (I'd prefer to get the EM one working to avoid paying the 10$ in shipping for like 3 capacitors for the Etherwave one unless there's a reason)

Thank you, I appreciate your help.

"On the right side of the circuit diagram on pg. 3, you can see an incorrect pinout for the positive regulator."  - nato

Ah, jeez, I totally missed that.  Was looking for pin numbers on the schematic.

"I did actually try using the pinout from Moog and it bulged out a capacitor. I do have both the positive (LM78L12) and negative (LM79L12) regulators, I do know they have different part numbers, and I am aware of the different pinouts for different packages - I'm using the TO-92 3-leg."

I'm looking at National Semiconductor datasheets on the web and the Moog schematic bottom view pinouts seems correct for the TO-92 package of both devices?

BTW, these little guys can only do 100mA max under fairly ideal conditions, you might want to use TO-220 types if they get too hot.

"Is the max amperage of my AC/AC adapter too high or is there any significance of the +-16V points being at 17.5V instead?"

No, that seems fine.

"Also, in that Etherwave power circuit, why is there another set of ceramic caps, different diodes, and the output caps mismatched in value (4.7 vs .1u)? Why/how would that change the behavior of the circuit?"

I can only assume they ran into regulator oscillation or power supply modulation issues?  Regardless of what's in the Moog schematic, I'd follow the datasheet recommendations first.  I would also use the latest schematics if possible, here's Roger's: https://d-lev.com/research/Updated_Annotated-Etherwave-Schematic.pdf

A bulging / exploding electrolytic is usually a (dramatic!) sign of incorrect capacitor polarity or AC getting to it.  Check your diodes to make sure they are wired in correctly and that they are still functioning.  Remove the regulators and check that the open circuit voltage at the caps is good.  If the regulator output is way too low then it is either wired in wrong or blown.

Do you have access to a scope?  You'll really need one for this kind of project.

"On the right side of the circuit diagram on pg. 3, you can see an incorrect pinout for the positive regulator."  - natoAh, jeez, I totally missed that.  Was looking for pin numbers on the schematic."I did actually try using the pinout from Moog and it bulged out a capacitor. I do have both the positive (LM78L12) and negative (LM79L12) regulators, I do know they have different part numbers, and I am aware of the different pinouts for different packages - I'm using the TO-92 3-leg."I'm looking at National Semiconductor datasheets on the web and the Moog schematic bottom view pinouts seems correct for the TO-92 package of both devices?BTW, these little guys can only do 100mA max under fairly ideal conditions, you might want to use TO-220 types if they get too hot."Is the max amperage of my AC/AC adapter too high or is there any significance of the +-16V points being at 17.5V instead?"No, that seems fine."Also, in that Etherwave power circuit, why is there another set of ceramic caps, different diodes, and the output caps mismatched in value (4.7 vs .1u)? Why/how would that change the behavior of the circuit?"I can only assume they ran into regulator oscillation or power supply modulation issues?  Regardless of what's in the Moog schematic, I'd follow the datasheet recommendations first.  I would also use the latest schematics if possible, here's Roger's: https://d-lev.com/research/Updated_Annotated-Etherwave-Schematic.pdfA bulging / exploding electrolytic it is usually a (dramatic!) sign of incorrect capacitor polarity or AC getting to it.  Check your diodes to make sure they are wired in correctly and that they are still functioning.  Remove the regulators and check that the open circuit voltage at the caps is good.  If the regulator output is way too low then it is either wired in wrong or blown.Do you have access to a scope?  You'll really need one for this kind of project.

You're right, the Moog diagram is a bottom view which I didn't realize. I do know what the bulge means, and with a 2200uF cap that's no joke! Happened because I, in desperation, misread the Moog diagram as a top view (flipped IN/OUT leads). Diodes are all lined up properly, and I'm using fresh components. For a scope I have one of those ADALM2000s that plugs into my laptop.

Rearranged it on a prototyping board, testing as I go, and got an arrangement that works. No oscillation, and I get 11.8V and -12.5V at the regulator outputs (but I soldered leads on and it's -13V at the end of the orange negative lead somehow). The issue before may have been my solder bridges? (they aren't the cleanest) or maybe my component placement. Will 11.8 and -12.5/-13V be close enough to the +-12V I need? I know theremins can be very sensitive. (Follow up: can I just epoxy the bottom instead of using standoffs or is that bad form?)

Thank you so much!

Edit: When I apply any load the negative supply sits at -16/-17V, so I guess there's still work to be done.

"No oscillation, and I get 11.8V and -12.5V at the regulator outputs (but I soldered leads on and it's -13V at the end of the orange negative lead somehow)."  - nato

11.8 is OK, but -13V seems dangerously out of spec to me.

"The issue before may have been my solder bridges? (they aren't the cleanest) or maybe my component placement."

They could be cleaner.  Do you have a bottle of rosin or no-clean flux?  If not get one and use it on everything before you solder.  I pre-tin all wires too, even pre-tinned bus wire, and wipe the iron tip on a cotton rag or paper towel right before every joint.

"Will 11.8 and -12.5/-13V be close enough to the +-12V I need? I know theremins can be very sensitive."

Stability depends more on steady regulation than absolute voltage.

"(Follow up: can I just epoxy the bottom instead of using standoffs or is that bad form?)"

What if you need to repair it or work on it some more?

"Edit: When I apply any load the negative supply sits at -16/-17V, so I guess there's still work to be done."

Sounds like a bad regulator or a bad connection on the regulator ground pin.