This project shows how we can use a normal speaker as a microphone and usually, a microphone converts sound into electrical signals. However, a speaker can also do the same work in reverse, therefore, this circuit becomes a simple and low-cost solution when we do not have a microphone. Moreover, it works well for basic […]
Audio Circuits
Low Impedance Input Transistor Preamplifier Circuit
This post explains about a Low Impedance Input Transistor Preamplifier Circuit which is designed especially for small audio signals like microphone, guitar pickup and other low level sources. Also, the circuit uses one NPN transistor BC109C and few resistors and capacitors as it increases the weak signal voltage so next stage amplifier can use it […]
12V Dynamic Mic Preamplifier Circuit
To begin with, this project is about a simple 12V Dynamic Mic Preamplifier Circuit which uses two NPN transistors BC549 and to increase very small audio signal from a dynamic microphone. Moreover, the circuit gives enough gain so we can feed the signal to an amplifier or recording system and also it works on 12V […]
UJT Based High Voltage Mini Audio Amplifier Circuit
To begin with, the circuit in this article shows a simple high voltage mini audio amplifier which uses one UJT transistor Q1 2N2646 and one power transistor Q2 AC187. This UJT Based High Voltage Mini Audio Amplifier Circuit works with a high supply of around +125V and it can drive a small 4 ohm speaker […]
Transformerless Audio Amplifier Circuit using Germanium Transistor
In this post we will understand about a simple power amplifier circuit using AC176 and AC126 type PNP germanium transistor in OTL (output transformer less) design. Also, this circuit gives audio power directly to speaker without output transformer, it is low voltage circuit and works with 9V battery. Therefore, the circuit design is easy and […]
Low Impedance Driver Circuit using BJT Transistor
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 […]