transistor ignition - the best of both worlds

4-10 — elektor april 1980 transistor ignition Photo 1. Prototype of the Elektor transistor ignition. breaker points is controlled by the distributor cam. When the points are opened, the current through the primary winding (PW) of the coil is interrupted, thereby causing a large voltage to be induced in the secondary winding (SW). When the contact breaker points close, the current through the primary of the coil will increase exponentially to a value 1p in the time t1, as shown in the graph of figure 2. The value 1p is deter- mined by the resistance of the primary winding and the battery voltage. The spark energy released by the points opening after time t1will be at a maximum. The coil has been designed so that the dwell angle (which dictates the time that the points are closed) can be adjusted allowing the maximum permitted engine revolutions to be reached and the coil fully loaded (just!). We are now faced with a problem. If the dwell angle drops, the primary voltage! will no ...