Their benefits are such that it’s become surprisingly rare to see a traditional linear power supply with a mains-frequency transformer and rectifier circuit, so [ElectroBoy]’s dual voltage PSU ...

[Ian Johnson] was enduring this pain with a couple of Circuit ... 0-30VDC 0-3A Bench Power Supply #CSI3003X-5 Single variable output 0-30VDC 0-5A Bench Power Supply #CSI3005X5 Dual variable ...