Electronic Test equipments


Simple 555 ICs tester circuit

Most IC-555 is used to generate frequency, and sometimes we need to know. Is it good or bad© But normal multimeter cannot check it. Thus, I make a simple 555 ICs tester circuit. Which is tested correctly and faster. How it works Resistors R1-R3 acts as limit current and reduce voltage to LED1-LED3. Which is […]


Diode tester circuit using IC-741 and LED

This diode checker circuit can check the diode the good or bad and also can indicate its polarity. How it works In Figure 1, There are IC1, R1, R2, R3, C1 include as the oscillator circuit that generate the square wave out to pin 6. This signal will be an AC that is symmetrical waveform. […]


555 audio ohmmeter circuit

555 audio ohmmeter circuit This is a 555 audio ohmmeter circuit. Some times, we need to measure roughly the resistances only. In this we can know the resistances by the audio so also fast check. This circuit will use the resistors that unknown value to compare with many the reference resistors. In Figure 1 is […]


1KHz Signal injector for electronic technicians

A signal injector is important tools for the electronics technicians it small and cheap. This project is better the simple circuit because it has 1KHz and many frequency harmonic. The normal signal injector has a square wave output about 1KHz. Which the square wave has lot of harmonic and up to many MHz so can […]