The standard hot shoe connection (ISO 518) does not provide a general power output. The center pin and shoe/ground are essentially just the flash-sync switch connection, and PC sync works the same way.

On most cameras, the extra hot shoe contacts are proprietary and mainly used for communication features such as TTL flash control and high-speed sync, not for powering accessories. There is no single universal pinout for those added contacts.

Some systems do provide power on extended hot shoe contacts for specific accessories—examples mentioned include newer Micro Four Thirds and some Fuji shoes, often for small flashes or other dedicated accessories. But those implementations are brand-specific, and in practice the extensions are not generally standardized across manufacturers.

So for a Pentax K-5, you should not assume the extra contacts provide usable accessory power unless Pentax specifically documents it. For a DIY accessory, it’s usually more practical and compatible to give the accessory its own power source rather than relying on camera hot shoe power.