I would prefer that both references have almost the same voltages. Which LED did you use? Did you check that the reg oscillates? Try replacing R17 and R19 with 1K and increase the current through the reference. A long time ago, I made four such references and the differences were in tens of mV.To quote personal messages probably not very nice but want to share finished and working project ant to thank you all for helpful advices. My reference voltages from GLED431 slightly off, at the positive rail 6.7V and at the negative 6.85V and leds on negative rail are a little bit lighter. But I put trimmers to have a possibility to adjust output voltage and I can set exactly 15V. Should I worry about these reference voltages?
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Yes, it was my fault. I already noticed that. Just put a wrong resistor (instead of 390R I put 1k and opposite for another one). Now everything is fine. LED’s are from old stock green SMD and I do not remember exactly the type. But voltage drop across one is about 1.8V. So, chain is from 3 leds and one 1N4148 diode.
Looks like I was happy too earlyI would prefer that both references have almost the same voltages. Which LED did you use? Did you check that the reg oscillates? Try replacing R17 and R19 with 1K and increase the current through the reference. A long time ago, I made four such references and the differences were in tens of mV.
On my scope the picture is not very pleasant:
c11/c12 caps are correct. What else can cause problems?