Yes you are Absolutely right ......... relay used has ampere rating around 5A ....the Power Source for Motor is A bulkier Battery ...And the idea is to use Separate power source for the schmitt trigger side and relay/ motor side .....Also the output of the comparator is used to trigger a Monostable with width 3Sec Which is connected to the starter Switch of the Diesel Engine ......When the voltage falls below the lower trip point the supply to diesel engine spark plug is cut ....So three Control signals are generated as the output of Schmitt trigger ....
The general picture is
1.When System is just started -
Motor is on ,The Supply to spark plug is off,Monostable out to Diesel Engine Starter is off.
2.When Voltage crosses the upper trigger point ,Motor turned off,Monostable on for 3 sec for starter and Spark plug supply on
3.When the voltage comes below lower trigger point ,motor turned on ,and diesel is turned off by turning off the spark plug supply ..
We Intend to use 555 Cmos Version ...Is there any Better IC ?.....