high quality tone control circuit by transistor low noise

8/17/2019 High Quality Tone Control Circuit by Transistor Low Noise

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High quality tone control circuit by

transistor low noise

Contents [hide]

1 1. Three transistors pre tone circuit

2 2. Classic Tone Control by 2 Transistors C945)

3 3. Stereo Tone Control using 2 transistors C945

4 4. Four transistors High quality Tone Control circuit

5 5. OLD Tone control circuit with four low noise transistors

6 6. Classic Tone control circuit with low noise transistors

7 7. High quality Tone Control Mono by 5 Transistors C945)

1. Three transistors pre tone circuit

Today I meets Classic Tone control circuit. That is use low noise transistor model.

which this circuit the interesting , because transistor entirely then have a voice good and

economize good. From circuit this use transistor 3 pcs. For pretend pre tone model

mono , if you want to use are the system stereo. As a result build this circuit enhances

again the group only.

The prominent point of this circuit again type , be use power supply source good wide

be about 9V – 18V and should be dc regulator with. The detail is other friends see in thecircuit adds yes.

2. Classic Tone Control by 2 Transistors C945)

This be tone control circuit ,The small-sized. It the character Mono by use transistor just

2 PCS important equipment performs to enlarge sound signal gives the power goes up


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,and have a button fines to decorate the sound completely. It be fine decorate the

popularity in the sound , fine decorate the treble , and fine decorate the bass as well.

It is convenient for a novice wants to try build Pre Tone control circuit keep be usable.

The prominent point of this circuit be seek the equipment easily , Electronic part replace

can be finished or can antiques sheep comes to use all right ,such as The transistornumber C828 may use the number C945 or C1815 or The other all right. For the level

power supply also get wide be about 12V to 24V at 50mA you can see other detail in

the circuit.

The circuit diagram of Classic Tone Control by 2 Transistors C945)

The PCB layout and components layout

3. Stereo Tone Control using 2 transistors C945

This circuit Tone Control Stereo, 2 Transister : C945 = 2 part.

Supply Volt min 12V


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The Circuit of Tone Control Stereo by Transister C945x2.


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PCB Tone Control Stereo by Transister C945x2.

4. Four transistors High quality Tone Control circuit

Designing power amplifier Circuit is high quality. The some is the thing that must think

over most. Be Pre tone control circuit , but friends must not worry. I has this circuit that

it transistor all work in feeding character gets back to model specialty. Be use Constant

Current source be something bias that get from LED help have the stability in manner

temperature work of Q1 and Q2 improve. The input can take a signal has since 100mV-

1V don’t fear about Over Load , and the crazy low very. For other equipment can

choose use general equipment. By sound quality still use well yes.

5. OLD Tone control circuit with four low noise transistors

If you have electronics old equipment, keep many long ago year, unknow build

Electronic Project good. I begs for to advise pre tone control circuit this. By it can fine

to decorate the sound Bass,Treble and Volume well.There is the prominent point that

use transistor, But be of good quality of good sound doesn’t be defeated the circuit that

uses the integrated circuit. By the thing that me observes clear, be the noise is low,

bland sound are good. from your circuit can use transistor number C945 or C828 or

C1815 can replace. Which the price is inexpensive the hardware is other may get not

difficult. The power supply , should choose that be model dc regulator 12V to 24V

building may use PCB a bird purposes all right which , good easy.


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6. Classic Tone control circuit with low noise transistors

This tone control circuit diagram of the home audio stereo is very well. It low noise and

sound is beautiful because use the quality transistor.

In picture we used three transistor number are C945 or C828 or C1815 or C458 They

are old electronic components but useful now. They are mono form if you want stereo

system, to make two section R+L. The VR1 is 100kB for finning treble tone sound. The

VR2 is 100K for finning bass tone audio as well. The VR3 is 100Ka for control volumeoutput. The VR4 is 100KW for control balane sound fo other channel. The power

Supply Voltage used min 12V and min than 80mA .

We hope this circuit will be do you are enjoy a home audio. good luck.


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7. High quality Tone Control Mono by 5 Transistors C945)

I am interesting about stereo amplifier high quality. My father tell me it must hear

sound well, low noise and so loudly.

Usually audio tone control made with a transistor that low noise , but less power than

used IC systems. I think this circuit will be that because it has four transistors in

diagram.we can also use to boost up a little audio signal.

In the image circuit is mono form. The transistors has five, number C945 or C1815 or

C828 . I hope you can find it at general electronic store or inside an old pcb. You can

use the power supply source during voltage 12V to 24V at minimum current at 100mA.

The picture no. 2 is PCB diagram for make this project, it small size so easy to use. You

can use StripBoard-3U Uncut Strips 1 Sided PCB because it has a few components.


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Simple Audio Preamplifiers

If you try to look for a good and simple schematic of an audio preamplifier, which can be

easily assembled, you will realize how difficult is to find it. To fill this gap, we propose

4 small audio preamplifiers that besides their simplicity, they exhibit excellent sound

characteristics. Although each preamplifier uses only 2 transistors, it exhibits excellent

sound quality.

Each preamplifier is able to boost a weak audio signal at an adequate level, for driving

the input of a final amplifier. All the projects in this article were assembled and tested, so

we can guarantee that their characteristics correspond to those declared.

Since all the schematics presented here are monophonics (support a single audio channel),

you may wish to build two identical circuits to use them for a stereo source. Taking into

consideration the simplicity of the circuit boards and their low cost, this will not be a

problem.

The circuit schematic for the first audio preamplifier is presented in fig 1. The preamplifier uses only two NPN transistors. Both transistors are BC172. You may also

use BC547 instead, or another equivalent type as well.


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Figure 1. The first

simple preamplifier circuit

The technical features of first preamplifier are summarized as follows:

Nomimal voltage: 12V

Current consumption: 1.2mA

Voltage gain: 50-55

Maximum input signal level: 150 mV p/p

Maximum output signal level: 8 V p/p

Frequency response: 20 Hz to 200 KHz

Although the recommended supply voltage is 12 volts, the preamplifier can be powered

as well from any voltage source ranging from 9 volts to 15 volts. If you choose to use 9-

volt, the maximum input signal amplitude will be limited to 120 mV p/p. Significant

distortion may be present, if you exceed this limit.

It worth’s to remind that in order to convert the value of a voltage expressed in volts peak

/ peak in a voltage expressed in volts (rms), you must divide the p/p value into the fixed

number 2.82. Thus, 150 mV p/p are equivalent to:

150/ 2.82 = 53 mV rms

The maximum output voltage of 8 volts p / p corresponds to an rms value of:


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8/ 2.82 = 2.8 V rms

In fig.1, we have also included the nominal bias voltages at certain points of the circuit

(given a power supply voltage of 12V). Since there are tolerances at components values,

do not worry if you measure slightly different voltages than those presented in figure 1.

Figure 2. Printed Circuit Board artwork for the 1st circuit

To simplify the assembly procedure, we have designed an appropriate small printed

circuit board. You may easily etch and drill this small PCB presented in figure 2, and you

may follow the assembly guide of figure 3 for soldering the components.

Photo 1. The electronic board of the 1st preamplifier

When placed on the printed circuit board, transistors TR1-TR2 must be placed with the

flat side of their body pointing to the left, as shown in Figure 3. Remember also to place

correctly the electrolytic capacitors according to the correct polarity.


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Figure 3. Assembly details for the

1st preamplifier

Another simple audio preamplifier is shown on figure 4. This specific design uses also

the same transistors used in the previous design, but differs from the classic pattern of a

transistor preamplifier, because the base of the second transistor (see TR2) is directly

connected to the collector of the first transistor and the signal output is provided from the

emitter of the final transistor, rather from its collector.

Figure 4. The 2nd electronic

schematic of a simple preamplifier

This preamplifier is capable to accept at its input, much stronger signals than the previous

design. It is capable to accept as much as 2 volts peak / peak at its input –which is about

0.7 volts rms.

The technical features of this specific preamplifier are summarized as follows:

Nomimal voltage: 12V


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Voltage gain: 4.8

Maximum input signal level: 2V p / p

Maximum output signal level: 9.6 V p / p


Figure 5. Circuit Board artwork for the 2nd circuit

The recommended supply voltage is 12V, but the audio pre-amplifier of figure 4 can be

as well powered from voltages within the range of 9 to 15 volts. The circuit is extremely

simple and you may easily assemble it using the small PCB presented in figure 5.


2nd preamplifier


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Photo 2. The electronic board of the 2nd preamplifier

The third schematic of an audio preamplifier is presented in figure 7. It has the advantage

of being an adjustable-gain amplifier, and its absolute voltage gain may vary from about

10 to 33. The gain can be adjusted from R4 potentiometer.

Figure 7. The 3rd electronic


In this schematic, the base of the second transistor (see TR2) is directly connected to the

collector of the first transistor (TR1), and the output is taken from the collector of TR2,

via C4 capacitor.

Figure 8. Circuit Board artwork for the 3rd circuit

Setting R4 trimmer to its maximum resistance value will set the amplification to itsmaximum value (about 33); turning it to its minimum value, will set the amplification to


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its minimum value (about 10). It is obvious that setting the trimmer halfway you’ll get

about the half of the maximum amplification.


3rd preamplifier

The technical features of the preamplifier of figure 7 are summarized as follows:

Recommended power supply: 12V


Voltage gain: adjustable from 10 to 33

Maximum input signal level: 0.3 to 0.8V p / p (for maximum and minimum gain,

respectively)

Maximum output signal level: 9.6 V p / p


Photo 3. The electronic board of the 3rd preamplifier


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To build this preamplifier, use the recommended PCB of figure 8 and follow assembly

instructions of figure 9. When placing the transistors, make sure for the flat side of their

body to point to the left, as clearly stated in Figure 9.

As well as the previous designs, the preamplifier of figure 7 can be also powered from

voltages within the range of 9 to 15 volts.

Finally, we present a fourth design of an audio preamplifier. The specific circuit

schematic is shown in figure 10, and it is suitable to amplify very weak audio signals. It

has very high gain and uses a PNP and an NPN transistor.

Figure 10. The 4th electronic


For the PNP transistor, you may use BC.213, BC.308, BC.328 or another equivalent type.

For the NPN, you may use BC.172, BC.547 or other equivalent types.

The technical features of the 4th preamplifier can be summarized as follows:

Recommended power supply: 12V


Absolute voltage gain: 115

Maximum input signal level: 70 mV p / p

Maximum output signal level: 8 V p / p



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Although the recommended supply voltage is 12 volts, the preamplifier can be powered

as well from a voltage source ranging from 9 volts to 15 volts.

If you choose to use 9-volt, the maximum input signal amplitude will be limited to 50 mV

p/p, otherwise the output will be distorted.

Figure 11. The printed circuit board for the 4th circuit

To build the preamplifier, use the recommended PCB of figure 11 and follow assembly

instructions of figure 12. When placing TR1, marked as BC213, BC308 or BC328, turn

the flat side of its body to the right, and when placing TR2, marked as BC172, BC547,

turn the flat side of its body to the left.


4th preamplifier

To avoid failures follow these guidelines:


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- When connecting the 12 V power supply, be careful not to reverse polarity (do not

reverse the negative wire with the positive one), because you will damage the transistors.

- Use shielded cable for the input signal, as well for the output signal and connect wire-

shield to ground (the negative power terminal).

All the circuits presented here, have low output impedance and you do not have to worry

if they will match to the input impedance of a final amplifier. They will be fine to boost

the input of a 20K input impedance amplifier; they will be fine as well to drive a 50K, or

a 100K input impedance.

Photo 4. The electronic board of the 4th preamplifier

high quality tone control circuit by transistor low noise

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