便携式混频器电路PortableMixer

便携式混频器电路 Portable Mixer
  Design description:
  The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance.
  The mixer is formed assembling three main modules that can be varied in number and/or disposition to suit everyone needs.
  The three main modules are:
  Input Amplifier Module: a low noise circuit equipped with a variable voltage-gain (10 - 100) pre-set, primarily intended as high quality microphone input, also suitable for low-level line input.
  Tone Control Module: a three-band (Bass, Middle, Treble) tone control circuit providing unity-gain when its controls are set to flat frequency response. It can be inserted after height=449 src="/data/attachment/portal/201007/ET30794201007221016341.jpg" width=593 border=0>
  Input Amplifier Module
  
  Parts:
  R1,R2,R7_______22K 1/4W Resistors
  R3,R4,R5_______47K 1/4W Resistors
  R6______________4K71/4W Resistor
  R8,R13________220R 1/4W Resistors
  R9______________2K 1/2W Trimmer Cermet (See Notes)
  R10___________470K 1/4W Resistor
  R11___________560R 1/4W Resistor
  R12___________100K 1/4W Resistor
  C1____________470nF 63V Polyester Capacitor
  C2,C8_________100?F 25V Electrolytic Capacitors
  C3,C4,C5________2?2 63V Electrolytic Capacitors
  C6_____________47pF 63V Ceramic Capacitor
  C7______________4?7 63V Electrolytic Capacitor
  Q1____________BC560C45V 100mA Low noise High gain PNP Transistor
  Q2____________BC550C45V 100mA Low noise High gain NPN Transistor
  IC1___________TL061 Low current BIFET Op-Amp
   
   
  Circuit description:
  The basic arrangement of this circuit is derived from the old Quad magnetic pick-up cartridge module.
  The circuit was rearranged to cope with microphone input and a single-rail low voltage supply.
  This low-noise, fully symmetrical, two-transistor head amplifier layout, allows the use of a normal FET input Op-Amp as the second gain stage, even for very sensitive microphone inputs.
  The voltage-gain of this amplifier can be varied by means of R9 from 10 to 100, i.e. 20 to 40dB.
  Notes:
  R9 can be a trimmer, a linear potentiometer or a fixed-value resistor at will.
  When voltage-gain is set to 10, the amplifier can cope with 800mV peak-to-peak maximum Line levels.
  Current drawing for border=0>
  Parts:
  P1,P2_________100K Linear Potentiometers
  P3____________470K Linear Potentiometer
  R1,R2,R3_______12K 1/4W Resistors
  R4,R5___________3K91/4W Resistors
  R6,R7___________1K81/4W Resistors
  R8,R9__________22K 1/4W Resistors
  R10___________560R 1/4W Resistor
  R11___________100K 1/4W Resistor
  R12___________220R 1/4W Resistor
  C1______________1?F 63V Polyester Capacitor
  C2_____________47nF 63V Polyester Capacitor
  C3,C5___________4n7 63V Polyester Capacitors
  C4_____________22nF 63V Polyester Capacitor
  C6,C8_________100?F 25V Electrolytic Capacitors
  C7______________4?7 63V Electrolytic Capacitor
  IC1___________TL061 Low current BIFET Op-Amp
  Circuit description:
  This is a straightforward design using the Baxandall-type active circuitry slightly modified to obtain a three-band control. Total voltage gain of this module is 1 when controls are set in their center position.
  Notes:
  Current drawing for border=0>
  Parts:
  P1,___________100K Linear Potentiometer
  P2_____________10K Linear Potentiometer
  R1,R2,_________15K 1/4W Resistors
  R3,R4,R11,R12_100K 1/4W Resistors
  R5,R6__________22K 1/4W Resistors
  R7,R8_________390K 1/4W Resistors
  R9,R10________560R 1/4W Resistors
  R13___________220R 1/4W Resistor
  C1,C2_________330nF 63V Polyester Capacitors
  C3,C8_________100?F 25V Electrolytic Capacitors
  C4,C5__________10pF 63V Ceramic Capacitors
  C6,C7___________4?7 63V Electrolytic Capacitors
  IC1___________TL062 Low current BIFET Dual Op-Amp
  Circuit description:
  The schematic of this circuit is drawn as a stereo unit to better show the input Main Fader and Pan-Pot connections. The TL062 chip contains two TL061 in the same 8 pin case and is wired as two virtual-earth mixer amplifiers having a voltage gain of about 4, to compensate for losses introduced in the passive Pan-Pot circuitry. Therefore, total voltage-gain is 1.
  Each channel added to the mixer must include the following additional parts:
  P1, P2, R1, R2, R3, R4, C1 and C2.
  These parts must be wired as shown in the above circuit diagram, connecting R3 and R4 to pin #2 and pin #6 of IC1 for Right and Left channel respectively. These IC1 pins are the "virtual-earth mixing points" and can sum together a great number of channels.
  Notes:
  Current drawing for one stereo Main Mixer Amplifier Module is 800?A.
  Frequency response is 20Hz to 20KHz - 0.5dB.
  Total HARMonic Distortion measured @ 2V RMS output = < 0.008% @ 1KHz; < 0.017% @ 10KHz.
  THD is 0.005% @ 1V RMS output.
  Maximum undistorted output voltage: 2.8V RMS.
  
  Further Parts:
  To parts listed above should be added: one Main on-off SPST switch, a LED used as pilot-light with its dropping 2K2 1/4W series-resistor, DPDT switches to enable or omit Tone Control Modules as shown in the Block diagram, input and output connectors of the type preferred, one stereo dual-gang 100K potentiometer to fade the Stereo Line Input as shown in the Block diagram, battery clip, PP3 9V battery, knobs etc.