Here is a low-cost multitester that can be used to test the state of practically all the electronic components, from resistors to integrated circuits (ICs). It is intended for use by beginners. It just requires a few components yet is able to detect polarity, continuity, logic states, and the activity of multivibrators despite its small size. The circuit takes advantage of the biasing property that bipolar transistors have and is extremely straightforward. In order to provide the results of the test, transistors T1 and T2 perform the function of transistor switches by driving the red and green halves of the bicolor LED1 individually. Working of a Multitester Because there is no longer any forward bias, the conductance of transistor T1 is terminated when power is supplied by depressing switch S1. Simultaneously, transistor T2 begins conducting once it has drawn base bias voltage from the battery and passed it through resistor R1. This makes it possible for the red half of the bicolor LED1 to light up. When a positive voltage is applied to the base of transistor T1 via resistor R3, the transistor conducts, which lights up the green half of the bicolor LED1. When transistor T1 is conducting, its base is grounded, which causes transistor T2 to switch off, so turning off the red half of the bicolor LED1. The signal that is acquired at the base of transistor T1 is therefore essential to the operation of the circuit. The following table details the testing techniques for a variety of components, along with the indications and findings that should be obtained.