I obtain my Bsc degree in Electronic engineering and we have started new company with 4 professional engineers who are expert in Electronics and software such as embedded system designing, matlab, java , C+ , PCB layout .etc . we are currently doing UAV autopilot research, pulse oximeter based Bio medical research collaborate with Fluke company ,Arduino demo board manufacturing etc . also done several project with micro processors and one of industrial project was re designing PUMA 562 robot arm controller design with DSPICs, and Matlab, So we have sound experience with microprocessors and circuit design which can use to assist your project also.
In your design we can use OPAMP buffer circuit to lower sink current and also we can use attenuator or a voltage divider to map 24V AC to 5V then we can remove one negative wave part from the signal and then get the maximum peak voltage. further detail u can discuss with me .
thank you
Chamika Gamage
Electronic engineer