An active frequency meter

This short paper deals with the theory and fabrication of a new frequency meter, which is used for the measurement of frequency in the range from a few hertz to 100 kHz. It is a frequency-selective bridge and is made of discrete passive R and C components and an integrated operational amplifier. At bridge balance, the frequency under measurement is given in terms of the values of resistors and capacitors only. Advantages, limitations, and sources of errors of the frequency meter are discussed. The theory is experimentally verified.