Sir mark krawczuk . . . . . . .
so i DONT need to rectify it to dc. the ac goes straight to the pcb.
OK then, I will need to further clarify my initial thought train for you .
The "24VAC" aspect immediately triggers the fact that a GOOD amount of commercial security cameras installations still depend upon 24VAC power routed to them.
Your units model number and brand would have initially be of a great help, AND STILL IS, because of need to research its schematic for some answers.
Considering, that units schematic is floating around to be able to consult . . . beyond that, it would have to be reverse circuitry engineered.
I highly suspicion that all one needs is a connection of a 12VDC or 24 VDC battery into that power connector.
Then the initial full wave bridge rectifier inside of that unit , which would normally be converting your AC voltage to DC voltage , would stop having that designation and is then merely being a DC directional coupler.
The DC then ends up across the systems main input electrolytic filter capacitor . . .which is now only serving as a storage reservoir enhancing function , since DC is INITIALLY already being present .
The rest of the power supply circuitry then takes its needs for creating other power supply branches and DC levels.
The "50 cycle" aspect is of no consequence, since it was just a "baggage" product of having been associated with having taken power from the mains.
Since the 70's and 80's any internal circuitry with critical frequency or timing aspects would not be relying upon 50~ referencing .
Instead, crystal or ceramic resonators associated with a microprocessor(s) or ancillary circuitry would be attaining any of those critical needs.
73's de Edd
