This booster circuit for audio signals, which is nothing more than an audio preamplifier for general use, had the original diagram published in a Popular Electronics of the 80s with changes, such as changing the original transistor by the BC548 or BC549 as well as other components for standardized values common in our days, the device can be mounted easily. The output is low impedance. The LED is optional and the consumption is low, a battery to power may be used. We recall that using the LED indicator which can be added on the source, the consumption increases. If power supply is used, it must have excellent filtration. Input cables and signal output must be shielded to prevent any noise.
