Single OP AMP rail splitter +-14V. Powered by 18650 3.7V battery, boosted by MT3608 buck boost module to its max. about 28 volts and then splitted by one op amp to create asymmetric mini power supply for desktop testing of audio op amp circuits. I used second half of the IC as well to improve current capabilities of the circuit. In that case you need to use small output resistors to compensate outputs issue caused by tolerances in inner circuitry of both op amps. Output ripple caused by MT3608 was slightly under 40mV with only 10uF filtrating capacitors (measured by oscilloscope). Use whatever capacity suits you. As OP AMP I used old LM 1458 but any other would do (LM 258, 358, TL072). The higher sink and source output of the op amp, the better. Do not use comparators! And of course the “new” ground is between filtrating capacitors.
Despite current limitations the power supply is more than sufficient for the purpose since OP AMPS use in average only a few mA.
