All in one multi-tester is quite expensive which may not affordable for every electronics beginners. Now, here is s cheap multi-tester that can be used to test the condition of almost all the electronics component from basic resistor to advance ICs. The circuit all in one tester is used to detect polarity, continuity, logic sate and also activity of multivibrator.
Circuit Description of All in One Tester
The circuit of all in one tester is so simple that it can also understand by beginners. The circuit of all in one tester contains two transistor and very few other passive components. Transistor T1 and T2 is used here as switch, driving the one half of bicolor LED each in order to give result of the test.
Initially, the circuit is in off mode, when switch SW1 is pressed, transistor T1 stops conducting due to lack of forward bias. At the same time transistor T2 takes base bias voltage from the battery through resistor R1 and conducts. This allows the red half of bicolor LED1 to illuminate.
Transistor T1 conducts when the positive voltage through resistor R3 is given to base of transistor T1 and light up the green half of LED1. In conduction of transistor T1 transistor T2 turns off and vice-versa.
Thus from the description, we know that the functioning of the circuit thus depends on the signal obtained at the base of transistor T1. The table below gives the testing procedure for various components with the expected indication or result.