Transistor tester is a simple electronic circuit that is useful to examine or test the condition of the transistor is good or faulty. The transistor tester circuit can be used to test the transistor NPN or PNP. The circuit is composed of oscillator circuit using a NAND gate IC CD4011 and 2 LEDs as status indicators in measuring transistor. The transistor tester circuit can use the power supply voltage 3VDC to 5VDC. Here is a picture of the transistor tester circuit in question.
The transistor tester circuit
The working principle of the transistor tester circuit is to provide a bias on the base of the transistor which in turn indicators LED test for a given pulse oscillator circuit. For example we test the NPN transistor, then when the pin 10 IC CD4011 then current will flow to the LEDs D1 through the transistor to pin 4 IC CD4011 is a logic 0 (NAND Gate). And at pin 10 Pin 4 High Low and then detained by the transistor current and not in the stream to D2 (NPN) and so on LED D1 will blink when the NPN transistor is in the test conditions. D2 LED indicator for PNP transistor tester.