Frankly, I am disappointed that we don’t see more discussion on this thread regarding circuit design and RC airplane applications. This is a RC airplane engine forum. On the other hand most guys I know don’t care about the electronics – they just want it to work.

Rob

1. You introduced a new circuit for consideration. Is this based on Jean Marc Veyrat’s design?

2. If so, he uses a single MOSFET to pulse the transformer. You propose using two MOSFET’s with a C.T. primary. Why? What are the advantages and disadvantages of each concept?

3. You propose using a MOSFET instead of SCR to fire the spark plug. Why? What are the advantages and disadvantages of each concept?

4. You talk about how critical the “flyback” (sic) transformer is. What makes it critical and how do we avoid problems when winding the transformer?

5. If we start discussing a new circuit design concept should we not open a new thread?

Gr8flyer

In the power board design concept that we are using, I noticed that the transformer coil ratio is 15t to 450t (or something close to that). This is a 1:30 ratio. Am I correct in assuming that capacitor C7 charges to .67 of full B+ voltage or (.67 x 5V) = 3.35 volts?

Thus (3.35V x 30) = 100 Volts.

If so, how are we getting 400+ volts across the secondary? What am I missing here?

Regards

Al