Simple Signal injector circuits using transistors

Do you know a signal injector circuit? If you are an electronic technician amateur in repairing of television or radio receivers. He said he is made a signal injector circuit to detect the signal in various sectors.

For example: in the sector amplifier, when the input signal of this circuit, if the amplifier is good, we can hear the sound from the speakers. Or we can check signal the following points by the oscilloscope more easily. Or we will apply to check the vertical yoke driver of the TV, too.

We have two circuits for you to try to make them below.

1. Simple Signal injector circuits

Simple Signal injector circuits using transistors

When see in simple signal injector circuit as shown figure this below, he used two transistors join together to be astable multivibrator which has a signal output frequency of 1,000Hz in square waveform.

A power supply voltage of this circuit is 1V to 5V. We recommend a AAA 1.5V-battery, it makes a level amplitude voltage peak at the output lower than 1Vp-p. Thus, the circuit is safe.

The creation of this circuit is simply only composted all parts of the perforated board.

The schematic of this projects is easy!

How to Builds.
The Copper PCB layout and The components layout
You can see the PCB layout and the components layout in above cause you builds easily this projects.

Parts will you need
Q1,Q2: BC548, BC547, BC549, 2N3904, 45V 100mA NPN Transistor
C1,C2: 0.015uF 50V, Ceramic Capacitor
C3: 10uF 25V, Electrolytic Capacitors
R1,R4: 3.3K, 0.25W Resistors tolerance: 5%
R2,R3: 47K, 0.25W Resistors tolerance: 5%
And others.

And others.


Friends. Instrumentation just is not enough. We see other circuits. You should make a better use.
1. Concentration test circuit

2. Simple transistor tester circuits

3. Morse Buzzer Alarm or Continuity Tester by IC 4011

4. Logic probe tester circuit

Related Posts


I always try to make Electronics Learning Easy.

Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments

I love electronic circuit. I will collect a lot circuit electronic for teach my son and are useful for everyone.
Close Menu