To begin with, this circuit shows a small audio amplifier which uses two BJT NPN transistors, they works with low impedance output like small speaker or earphone. Also, the circuit takes weak input signal and makes it stronger and runs on DC supply from +6V to +18V, as the circuit is simple, low cost and […]
Transistor Circuits
Transistor Based Audio Amplifier Circuit
A Transistor Based Audio Amplifier Circuit is a simple and useful audio circuit that increases weak audio signals into a louder sound signal. This circuit uses four transistors, namely two BC547 NPN transistors and two BC557 PNP transistors, because of its simple design, students and beginners can easily understand and build it. Moreover, this circuit […]
PIR Sensor Based PNP Switching Circuit for Output Control
In this tutorial, circuit uses a PIR sensor to control an output load through transistor switching, but the main purpose of this circuit is to turn ON the output when motion is detected and when PIR sensor detects motion, it gives a trigger signal After that, the NPN transistor and PNP transistor work together as […]
5V 4A Power Supply Circuit using IC 7805 and Parallel Transistors
In this post, the below designed circuit gives a stable 5V DC output with high current up to 4A which uses the 7805 voltage regulator IC and multiple TIP41C transistors connected in parallel, because the normal 7805 IC alone gives around 1A current and we add external power transistors to increase the output current. Moreover, […]
Three LED Blinking Circuit with NPN Transistors
This article is for Three LED Blinking Circuit with NPN Transistors that uses 3 NPN transistors, resistors, capacitors and a 9V battery, which works as an astable multivibrator, so it does not need any external clock signal. Instead, the circuit creates its own oscillation, because of this, the LEDs alternately flash ON and OFF at […]
Solar Sensor Based Security Alarm Circuit using Transistors
This is a simple and low-cost Solar Sensor Based Security Alarm Circuit using Transistors which uses a solar sensor for light sensing. The circuit gives alarm sound through the speaker when light level changes and it works mainly when darkness comes or when someone blocks light on the sensor. So we can use this circuit […]