fuel economiser - an R.P.M. indicator as an economy guide

11-04 - elektor november 1980 fuel economise an R.P.M. indicator as an economy guide. eÃÅfiwl A car engine is at its most efficient when the amount of energy it produces is closest to the amount consumed. This occurs at an engine speed that produces the maximum torque output. Outside of this quite small speed range energy is wasted. The fuel economiser provides both an optical and an acoustical guide to enable the driver to change gear at the optimum time and thereby keep the engine within its most efficient range. Although an r.p.m. counter is a useful instrument, it is not very helpful in terms of saving petrol. If it was to be used for this purpose it would have to be watched far too carefully to be effective and this would be too demanding on the driver. The circuit described here does not provide a complete r.p.m. indication but rather an indication of when to change gear in order to keep the engine speed at its most efficient. It also gives a warning when the maximum engin...