LM3 18 operational amplifier circuit, using single chip microcomputer to measure the frequency of sine wave. Amplification circuit, how to determine the magnification?
Don't have a headache. The amplification depends on the amplitude of the input signal. Usually, only those signals below 10 millivolts need to be amplified by the amplifier. The gate circuits of cd4069/40 1 1 with tens of millivolts or more can be connected in series to form an amplifier. Most frequency/voltage converters in digital multimeter are such circuits. What is the signal frequency you want to measure?