Ignition circuit for an internal combustion engine

摘要

The invention relates to an ignition circuit for an internal combustion engine in a hand-held implement, a tool being operated by means of a coupling. The ignition circuit has an ignition time control which connects a spark plug arranged in the combustion space of the internal combustion engine to a voltage source as a function of the crankshaft angle and the speed of rotation of the engine via a switch in order to trigger an ignition spark. In order to avoid coupling damage when the tool is blocked, there is provision to arrange a test value counter which is driven by means of a speed of rotation gate circuit and which, in the prescribed speed-of-rotation window of the gate circuit increases its value with each revolution of the crankshaft and the contents of the test value counter are compared with a prescribable limit value by a comparison device, the output of the comparison device which indicates that the limit value has been reached or exceeded activating a protection circuit which reduces the speed of rotation.