# Low Voltage Preamplifier Circuit with Tone Control

If you want to adjust the tone of audio in low voltage states. Is it impossible? Most tone control circuit requires a 12V power supply. Yes, it is real. this is a Low Voltage Preamplifier Circuit with Tone Control.

To begin with this circuit will connect the switch-S1, to apply the power supply to the circuit and the input have audio signal source.

Figure 1 the circuit diagram

## How it works

A function of each device do better

1. There are C1, C2 and VR1/1 are set the input audio signal to high frequency up, and VR1/1 adjust the treble for the left headphone.

2. The similar the C5, C6 and VR1/2 are set the input audio signal to high frequency up, and VR1/2 adjust the treble for the right headphone channel.

Recommended: Hi Fi audio tone control circuit using low noise transistors

3. When we want stereo sound, therefore, pitched the left headphone is equal to pitched to the right headphone.

So we use the VR1 is Dual Audio Potentiometer Because Changes in the resistance of VR1 / 1 is equal to the resistance of VR1 / 2.

And must to use C1 is equal C5, C2 is equal C6.

If you do not like that pitched voice, it can be modified circuit. By changing the value of C1, C2, C5, C6 and VR1.

But do not forget, the value of C1 is equal to C5 and C2 is equal to the value of C6.

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4. Adjusting the bass, the VR2 is dual audio potentiometer. Adjusts the audio signal to a lower frequency, both the left and right channel.

There are R1, R2, C3 and C4 determine the bass for the left headphone, And R3, R4, C7, C8 determine the bass for right headphone.

5. To change the device will change the frequency with C9, C10, C11. And the capacitor C12 acts as bring signal to the left and right.

Through the circuit bass treble adjustment, in to the transistors Q1, Q2, Q3 and Q4. The incoming signal is a signal that is both positive and negative.

When added to the positive halfcycle of C10 to C12 in the past Q2 and Q4 to Q2 and Q4 are amplified by the positive halfcycle.

The negative half is through C9 to C11 at Q1 and through the into the Q3. By Q1 and Q3 to amplify the voice over the negative halfcycle.

It has audio headphone output with both the positive and negative half. As the only input into the frequency of the audio signal changes. The frequency bass sound change is pitched to change that.

Figure 2 the PCB layout

Figure 3 the components layout

#### Parts you will need

0.25 W, +-5% Resistors
R1, R3: 18K (brown, gray, orange , gold)
R2, R4: 3.3K (orange, orange, red, gold)
R5, R6, R7, R8: 47K (yellow, purple, orange, gold)

Dual layer potentiometers
VR1, VR2: 100K type A

Electrolytic capacitors
C9, C10, C11, C12_10uF/ 16V

50V, ceramic capacitors
C1, C5: 0.0033uF (332)
C2, C3, C6, C7: 0.018uF (183)
C4, C8: 0.1uF (104)

Transistors
Q1, Q3: 2SA1015
Q2, Q4: 2SC1815
S1: SPST Slider Switch
Others

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