Old Timer Model Airplane Engine Electronic Ignition

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(NOTES:)

All the items needed to complete the above ignition system can be obtained from Larry Davidson, 66 Casa Mia Circle, Moneta, Va. 24121 (540)721-4563. His email is samchamp@jetbroadband.com Click Here to view his complete catalog of products. Larry has the complete solid state ignition unit, the high tension leads, spark plugs, and the coils. The complete system runs about $75.00 less shipping. Tell him Scott from Model Flight sent you.

This circuit is the circuit Bill Schmidt designed in the early 1980's. It is a time proven and reliable ignition system.

Use TIP42, 2N-5195, or SK series (SK-3083, SK-3189, or SK-3961) transistors.

Make sure you use the 10K ohm resistor at the spark plug on radio control ignition models or excessive radio interference will result.

The limiting resistor from the base of the transistor to the points should be between 18 and 22 ohms, or the trigger current can be excessive causing burning of the points. (This electronic ignition reduces deterioration of the points greatly compared to the old points-condenser circuit.)

Use a new strong coil as some other older coils don't work well in a transistor driven circuit.

Use 16 gauge wire or bigger from the battery to the coil or excessive voltage drop will reduce spark effectiveness.

You can use 3 nicads, 3 nickel metal hydroxides or 2 dry cell batteries for the battery source. Make sure you have between 3.0 and 4.0 volts at all times.

An external boosting battery source can be used to give a hotter starting spark, but is usually only needed when using dry cells. Parallel the booster battery across the model battery using a plug and jack.

The kill switch can be activated by timer or servo depending on the application.

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