Shabbos Oven

Question

I spoke to your father before Yom Tov concerning my GE shabbos oven. The issue is gram havorah. The oven circuitry includes a "grama switch" which was invented a few years ago by the Institute for Science and Halacha in Israel. It works by incorporating a random delay(from zero to one minute) between the off/on control and the oven ignition system. The key word is "random". The oven operator does not know when the oven will turn on. Rav Heinemann in Baltimore is the guy who convinced the manufacturers to in corporate this system in their products and he permits its use on Shabbos and Yom Tov. Your father told me that gram havorah is muttar, and therefore turning the oven on and off in "Shabbos Mode" is OK as is changing the temperature. The top burners have no such switch and one must use traditiional means of use. I installed a switch that turns off the electronic ignition for use on Yom Tov. Unk