The device is built around a single CMOS integrated circuit 4093 and functions as a universal tester for transistors, diodes, and electrical circuits.
When testing transistors, the emitter, base, and collector pins must be known. Depending on the transistor type and condition, LED indication is provided:
- D1 - for PNP transistors
- D2 - for NPN transistors
If the transistor is functional, the corresponding LED lights up. If the transistor is open, no LEDs light. In case of a short circuit, both LEDs light up.
During diode testing, if the diode is functional, the LED connected to the cathode lights up.
When testing electrical circuits or continuity, both LEDs light up, indicating a closed circuit.
The tester is powered by a 9 V battery and is suitable for quick testing of electronic components and wiring.

Technical Specifications:
Integrated circuit: CMOS 4093.
Functions: transistor, diode and circuit testing.
Indication: LEDs.
Supply voltage: 9 V DC battery.
PCB dimensions: 43 x 15 mm.

This product is a DIY assembly kit.