[TOMT]Book series featuring Dracula, Frankenstein, and other classic monsters

It was a series I read a bit of when I was around 10. I remember the first one was about an experimental piece of hologram technology being developed, so the protagonist boy and his friends watch the 1931 Dracula movie on it, inadvertently bringing Dracula to life. I distinctly remember one of the characters said the catchphrase "I'm off, said the madman" whenever he left the room and no one could figure out where he had gotten that from.