IC Power Amplifier

tone control schematic

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Saturday, 29 March 2014

Stereo Preamplifier with adjustment tone

Many times we needed to use a simple circuit of preamplifier, with few components and facility of made. This circuit use a opamp. the Motorola, TCA5550, that contains a double amplifier, as outputs for the adjust of volume, balance, treble and bass. These adjustment of all parameters become from a line monophonic linear potesometers, increasing by far the facility of manufacture. The placement these potesometers should become as much as possible, more near in IC1, so that is minimised the noise. The circuit does not require big current in order to it work.

Circuit diagram

Circuit diagram

Part List

  • R1-2-3-4=100 Kohms
  • RV1-2-3-4=100 Kohms Linear pot.
  • C1-2-8-9=4.7uF 63V
  • C3-4=100nF 100V MKT
  • C5-14=100uF 40V
  • C6-7=47nF 100V MKT
  • C10-11-12-13=220nF 100V MKT
  • C15-16=10uF 63V
  • IC1=TCA5500 Motorola

Skema 3 Band Equalizer Mono

Stereo Preamplifier With Bass Boost

This preamplifier was designed to cope with CD players, tuners, tape recorders etc., providing an ac voltage gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets, the bass frequency range is rather sacrificed. This circuit features also a bass-boost, in order to overcome this problem. You can use a variable resistor to set the bass-boost from 0 to a maximum of +16dB @ 30Hz. If a fixed, maximum boost value is needed, the variable resistor can be omitted and substituted by a switch.

Circuit Diagram:

Circuit Diagram


  • P1 = 10K
  • P2 = 100K
  • R1 = 100K
  • R2 = 100K
  • R3 = 15K
  • R4 = 10K
  • R5 = 22K
  • R6 = 15K
  • R7 = 1K
  • R8 = 470R
  • C1 = 2.2uF-25v
  • C2 = 2.2uF-25v
  • C3 = 470uF-35v
  • C4 = 1uF-35V
  • C5 = 2.2uF-25v
  • C6 = 47nF-63v
  • C7 = 22uF-25v
  • IC1 = TL072, Opamp
  • SW1 = DPST Switch


  • Schematic shows left channel only, but R1, R2, R3 and C1, C2, C3 are common to both channels.
  • For stereo operation P1, P2 (or SW1), R4, R5, R6, R7, R8 and C4, C5, C6, C7 must be doubled.
  • Numbers in parentheses show IC1 right channel pin connections.
  • A log type for P2 ensures a more linear regulation of bass-boost.
  • Needing a simple boost-in boost-out operation, P2 must be omitted and SW1 added as shown in the diagram.
  • For stereo operation SW1 must be a DPST type.
  • Please note that, using SW1, the boost is on when the switch is open, and off when the switch is closed.

Digital Volume Control

This circuit could be used for replacing your manual volume control in a stereo amplifier. In this circuit, push-to-on switch SW1 controls the forward (volume increase) operation of both channels while a similar switch SW2 controls reverse (volume decrease) operation of both channels. A readily available IC from Dallas semiconductor, DS1669 is used here.

Circuit Diagram:

Circuit Diagram:


  • J1 = RCA Audio Input Socket
  • J2 = RCA Audio Input Socket
  • C1 = 0.1uF-16V Ceramic Disc Capacitor
  • C2 = 0.1uF-16V Ceramic Disc Capacitor
  • C3 = 0.1uF-16V Ceramic Disc Capacitor
  • IC1 = DS1669 (is available from Dallas SCo.
  • SW1 = Momentary Push Button Switch
  • SW1 = Momentary Push Button Switch


  • Replaces mechanical variable resistors.
  • Electronic interface provided for digital as well as manual control.
  • Wide differential input voltage range between 4.5 and 8 volts.
  • Wiper position is maintained in the absence of power.
  • Low-cost alternative to mechanical controls.
  • Applications include volume, tone, contrast, brightness, and dimmer control.
  • The circuit is extremely simple and compact requiring very few external components.
  • The power supply can vary from 4.5V to 8V.
  • The input signal should not fall below -0.2 volts.

Bass-treble tone control circuit

circuit diagram

Bass-treble tone control circuit-Circuit diagram
The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of the bass, treble, balance and volume functions through application of DC voltages from a remote control system or, alternatively, from four potentiometers which may be biased from a zener regulated supply provided on the circuit. Each tone response is defined by a single capacitor chosen to give the desired characteristic.


  • Wide supply voltage range, 9V to 16V
  • Large volume control range, 75 dB typical
  • Tone control, ±15 dB typical
  • Channel separation, 75 dB typical
  • Low distortion, 0.06% typical for an input level of 0.3 Vrms
  • High signal to noise, 80 dB typical for an input level of 0.3 Vrms
  • Few external components required


Vcc can be anything between 9V to 16V and the output capacitors are 10uF/25V electrolytic

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