In this post we make a simple delay start circuit for diesel engines in order to enable a proper preheat
It happens to be well known that diesel engines need a preheating delay time of approximately 5 seconds. When we attempt to start the engine with the cold diesel it is not going to not start regardless of how rigorously we try. The truth is this adversely tends to make an engine of this type to start before warming up. The circuit we recommend will take around seven seconds before enabling us to start the engine.
The resistance of 47K and the capacitor of 100μF along with the transistor of the center are the ones that are responsible for recognizing the timing. The second transistor is liable for moving the coil of the relay as well as the latter is in charge of making it possible for the engine to start.
For this simple diesel engine delay start circuit we put together almost all the equipment inside a relay box very easily or in a suitable small molded case. For longer time delay we simply may tweak on the values of capacitor and resistance. The circuit is operated straight by 12V.