TACHOMETER CIRCUIT

An improved frequency to voltage converter utilizes an exclusive OR logic circuit to reduce the number of required capacitors. A squaring circuit provides a first train of squared pulses from a variable frequency input signal, and a pulse generator in response to the first train of pulses generates a time displaced second train of pulses. The first and second pulse trains are combined in an exclusive OR logic combination to thereby generate a third pulse train having controlled pulse widths. The third pulse train is thereupon integrated into a DC signal having mangitude related to and varying with the frequency of the input signal. Preferably first and second tracking current sources control pulse width and pulse height of the third pulse train so as to provide pulses of substantially constant energy to the integrator.