A few years ago, I developed a regulated power supply with three outputs: +5V, +12V, and -12V, primarily intended to replace the one found in the Prophet VS.
The characteristic of this power supply is that it is fundamentally a high-performance switching power supply, but not directly connected to the mains voltage; instead, it is powered by a step-down transformer providing 18V AC or, better yet, 24V AC. Consequently, this power supply does not present the dangers inherent in using switching power supplies that are directly connected to the mains.
As a result, the overall efficiency of this power supply is much better than that of a purely linear supply. The 5V output comes exclusively from the switching power supply section, whereas the two analog-dedicated supplies, i.e., +12V and -12V, are derived from high-quality linear regulators, followed by filters to suppress any residual harmonics. The voltage supplied to the linear regulators is just above the input voltage required for their operation.
With all these precautions, the power supply runs globally very cool and is capable of delivering 1A on each of its outputs.
Additionally, a special connector provides everything a processor-based system needs in terms of RESET and faulty voltage indication, thanks to the addition of a specific component that performs monitoring and control operations with precision. This component is a MAX707CSA+T. Note that a CR2032 battery holder is available, providing a backup power pin on this connector.
Finally, three connectors — including one specific to 3.5-inch floppy disk drives — are provided to facilitate connections.
In fact, this power supply can be used both for repairing synthesizers, as in the case of the Prophet VS in this example, and for powering any device operating on 5V requiring high-quality symmetrical power supplies for an analog section.
A new batch of these power supplies has been produced.
