mona kunpara,
I do have a circuit diagram for a simulator created many years ago by a fellow Biomed Tech, and for a calibrator I designed in school, and no I won't give them to you.
I will help you as much as I can with "your" design. And, I'm sure others will join in as they see where they can help with your efforts.
To quote someone "One test is worth a thousand expert opinions, but one expert specification is worth a thousand tests.
Start by writing down all the things you want your device to do.
What ECG parameters do you want your device to calibrate or simulate?
Is your expertise in hardware or software?
Ken