Some magnetos include an impulse system, which spins the magnet quickly at the proper moment, making easier starting at slow cranking speeds. The output of a magneto depends on the speed of the engine, and therefore starting can be problematic. Switchable magneto ignition circuit, with starting battery. Energy transfer systems provide the ultimate in ignition reliability. Such a system is referred to as an 'energy transfer system'. In this development, the induced current in the coil in the magneto also flows through the primary of the external coil, generating a high voltage in the secondary as a result. Many modern magneto systems (except for small engines) have removed the second (high voltage) coil from the magneto itself and placed it in an external coil assembly similar to the ignition coil described below. This gave the benefits of easy starting (from the battery system) with reliable sparking at speed (from the magneto). Some older automobiles had both a magneto system and a battery actuated system (see below) running simultaneously to ensure proper ignition under all conditions with the limited performance each system provided at the time. The Wright brothers used a magneto invented in 1902 and built for them in 1903 by Dayton, Ohio inventor, Vincent Groby Apple. Magnetos were used in these engines because their simplicity and self-contained operation was more reliable, and because magnetos weighed less than having a battery and dynamo or alternator.Īircraft engines usually have dual magnetos to provide redundancy in the event of a failure, and to increase efficiency by thoroughly and quickly burning the fuel air mix from both sides towards the center. Magnetos were used on the small engine's ancestor, the stationary "hit and miss" engine which was used in the early twentieth century, on older gasoline or distillate farm tractors before battery starting and lighting became common, and on aircraft piston engines. Although an electrical supply is available, magneto systems are used mainly because of their higher reliability. They are also used on piston-engined aircraft engines. where a battery-based electrical system is not present for any combination of necessity, weight, cost, and reliability reasons. Magnetos are not used in modern cars, but because they generate their own electricity they are often found on small engines such as those found in mopeds, lawnmowers, snowblowers, chainsaws, etc. In about 1902, Bosch introduced a double-coil magneto, with a fixed sparking plug, and the contact breaker outside the cylinder. Early magnetos had one coil, with the contact breaker (sparking plug) inside the combustion chamber. The spark plugs are connected directly from the magneto output. The engine spins a magnet inside a coil, or, in the earlier designs, a coil inside a fixed magnet, and also operates a contact breaker, interrupting the current and causing the voltage to be increased sufficiently to jump a small gap. The simplest form of spark ignition is that using a magneto.