The SC series tuning fork liquid level switch product line operates by the principle of detecting the change in the frequency of vibration of the forks as a result of the presence or absence of a fluid at the forks. Hence the technology name, tuning fork. The tuning fork vibration is created by a piezoelectric crystal excited by an electrical signal from the electronics. A second piezoelectric crystal produces an electrical signal as a result of the vibration transmitted to it through the forks by the first crystal. The electronics continuously monitors the signal from the second crystal in order to detect fluid presence and absence and activate the tuning fork liquid level switch output.