This is a Stereo VU Booster circuit. In this circuit, shown in the schematic diagram, transistor FCS9014 is used. Actually you can use almost any type of small signal NPN transistor. This transistor usually used for regulator and pre-amp circuit. Here is the schematic diagram of the circuit:

The schematic diagram show only one channel, so you have to build one other similar circuit for stereo channel. The input impedance of this circuit is at least 33k. The first transistor is employed to amplify the signal, and the second transistor’s function is for rectifying and buffering. You can see the second transistor’s base is not biased. This means that the positive cycle of the ac signal from 2.2 uF will directly drive the transistor, which is configured as emitter follower. To use this circuit, connect this circuit to audio channel before amplifier module. This circuit can also be connected to the wire connection before equalizer or tone control which will give good output when the equalizer or tone control is used.
Possibly Related Articles:
- Transformerless Voltage Booster Circuit: A DC-DC Step-Up Switching Regulator Using Transistors
A DC-to-DC step-up converter is traditionally implemented using transformer, working by converting the DC voltage to AC Voltage, step-up it using transformer, then rectify and filter the transformer’s output to ... - Discrete Bass Booster Circuit
This bass booster circuit can be used filter the input signal as part of internal circuit of an active subwoofer circuit. This circuit is not only boost the bass (low)... - Stereo Balance Indicator
This circuit presents a very simple and useful stereo balance indicator circuit that is based on few common external components. This schematic circuit is very simple to build. An visual... - True Stereo Indicator Detects L-R Signal Difference
This true stereo indicator is different from what we usually find on FM radio receiver, which is usually a pilot tone detector. A stereo broadcast from FM radio station contain... - LED Flasher Circuit Using Transistors
Classic LED Flasher Circuit This LED flasher circuit is a classic two transistor flip flop. This flasher circuit is very popular and it’s usually the first circuit to build when... - Capacitance Meter Circuit Using Transistors
This capacitance meter circuit is similar with previous meter circuit, but it uses transistors rather than logic gates. Here is the schematic diagram: You can see the circuit uses pnp... - Single Chip Stereo FM Transmitter Circuit: A Very Compact Design
ROHM (www.rohm.com) is originally a resistor producer company, but finally expand their business and produce monolithic IC, and this one used in our circuit is the example. The internal structure... - 53 dB Stereo Preamp for Tape or Phonographs
With the circuit shown in the following schematic diagram, both channels of this stereo preamp is constructed using RCA CA3052 quad AC amplifier. this pre-amplifier circuit is featured with tone... - Stereo Digital Volume Control
It’s good to use CS3310 because CS330 is a complete stereo digital volume control designed specifically for audio systems. This device has features like 16 but serial interface that controls... - 20 Watts Car Stereo Amplifier Using TDA2004
The main features of this powerful MULTIWATT® package (a trademark of SGS-THOMSON Microelectronics), a power amplifier IC chips designed specifically for car radio application, are the high current capability (3.5A)... - Stereo Tone Control with National 3D Sound
The LM4610 uses DC signal to control the tone (bass/treble), volume, and balance circuit. The advantages of using DC control is that you can use a mono potentiometer to control... - Voltage-Controlled Stereo Volume Control Using LM13600 OTA
What we can do with a stereo voltage-controlled volume control? There so many things, we can control our audio using a DAC which is controlled by a microcontroller, or we...
| 

