The above PSU delivers 14.6V to 18.5V. is designed for an extra low noise and hum rejection so you will find circuit elements you may not expect in a power
supply.
They’ve used a (toroid) transformer 2x18V, 1A (but…adapt to your needs!). It doesn’t necessarily need be a 1A or toroid. Just use a normal transformer.
Just keep in mind that for the curve tracer 50-60mA per rail is all that is needed.
As you can see they choose to place the power switch S1 (on the secondary (rather) and it has C7 and C8 in parallel to avoid switching noise.
The rectifier bridge with series resistors R1… R4 reduces the initial turn-on current impulse and C1…C4 suppresses the noise induced by rectification diodes.
C11 and C12 (ceramic) improve HF suppression. If fitted, always require D5, D6, D7, and D8 to provide reverse protection.
T1 and T2 provide clean, delayed regulators (IC8- IC9) turn-on. The combination R12, R13, C15, and C16 provide a lowpass filter to further noise suppression.
PS: R7 in the scan is hard to read. R7 = 1.5K
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