This is a stereo VU booster circuit diagram based on transistor FCS9014 which usually used for pre-amp and regulator circuit and switching. With simple circuit design, this device could be built easily. Scheme diagram, bottom PCB layout and component placement provided on the following image:
This circuit should be connected to audio channel before amplifier module. If you are using tone control or equaliser module, it’s better to connect this circuit to the wire connection before tone control / equaliser.
The transistors boost the audio signal from the input and then forward the signal to the VU meters. Adjust the VR/potensiometer to get the best sensivity of VU meter.
This stereo VU booster circuit works with wide range of supply voltage, 12VDC to 40VDC, you may connect this circuit parallel with amplifier circuit.