He compares two input signals, and depending on whether signal A is larger than signal B, or vice versa, changes the output signal. A comparator compares (engl Compare) so, just two signals. This example, simple two-step control are possible. Closely related to the comparator are Schmitt trigger and window discriminator.
Here links to comparator (Comparator) circuitry
Here you will find Schematic Circuit Diagram for DIY and further information on Comparator
|Operationsverstaerker as a comparator||www.loetstelle.net/grundlagen/operationsverstaerker/opamp_2.php|
|LC Messgeraet with comparator||www.digital-measure.com/html/de_lcmeter.htm|