Stereo Encoder with High Separation

A higher channel separation stereo encoder built with 3 iC’s 4066, 4047, 4013 and 741. It has a filter L, C5 for frequencies higher than 15kHz and an extra audio amplifier built with 741. This stereo encoder has a better design than this stereo encoder circuit but the principles are the same.

Stereo Encoder schematic components

R1 = R5 = 10K
R2 = R6 = 220K
R3 = R4 = R9 = 47K
R7 = R8 = 4.7K
R10 = 68K
R11 = R12 = 27K
R13 = 2.2K variable
R14 = 20K liniar
C1 = C2 = 1nF
C3 = C4 = C11 = 100nF
C5 = C10 = 10nF
C6 = 470pF
C7 = 100pF
C8 = 68pF
C9 = 10uF
L = 6.8mH
IC1 = 4066
IC2 = 4013
IC3 = 4047
IC4 = 741

Stereo encoder circuit schematic

schematic stereo encoder high separation


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  • AlbertH

    This “P. Marian” can’t copy properly and doesn’t understand the circuits he’s put on this site – they are all copies from elsewhere.

    The other half of the 4013 has been cut off the circuit diagram. It’s configured as a bistable to divide the 38 kHz at pin 2 of the 4013 and the 19kHz output connects to the crude filter at R9 through a 47k resistor. The inductor and capacitor resonate at 19 kHz and try to make the pilot tone closer to a sine wave.

    • KF5OBS

      And I was just wondering from where he stole it… Too bad he is to lazy to at least copy the explanation of how this circuit works. Maybe over his head?

  • Raj

    What is the detail of coil 6.8mH? Is hand wound coil or ”Blue+Grey+Orange” registor type choke? Or ”Blue+Grey+Golden”???????? Does it critical in value?? What is the job of 714 IC?

    • AlbertH

      Part of the circuit is missing. The other half of the 4013 needs to be connected as a bistable to divide the 38 kHz at pin 2 of the 4013 to give 19 kHz. The 19 kHz connects through a 47k resistor to the junction of R9 and the inductor.

      The 741 is being used as a simple lowpass filter in an effort to reduce the spurious outputs from this crude circuit. The 741 is too noisy and distorted for audio use – you’ll get better results from a TL071, but “P. Marian” doesn’t know enough to suggest that.

    • P. Marian

      It is hard to make the coil by hand so you can buy it. 741 IC is used as an amplifier.

  • vlado

    creo que la señal piloto sale de la pata 13 del ic2

  • Pentaconto

    Hello! Also I not speak english (sorry)! (I’m from Spain)

    Is correct this circuit ???

    I can not see the 19 KHz stereo tone pilot in this circuit.

    If IC3 oscillate to 38 KHz, then the 19 KHz tone is present in the output IC3 pin 10, and this tone is not connected to the output signal MPX in the circuit schematic. Then, MPX signal is not correct.

    Perhap (???) IC3 oscillate to 76 KHz , and IC2 (a flip-flop D type) divide this frequency by 2 (to 38 KHz) at the flip-flop outputs (IC2 pins 1 & 2 ) for use in the balanceed modulator IC1. Then, where is generate the 19 KHz tone?

    Some explanation about this, or circuit corrections ???

    • AlbertH

      See my corrections above.

      “P. Marian” has no real understanding of the circuits on this site, and so most of them have errors and omissions.

  • piero

    (ByItaly) Hello! I not speak english sorry!
    Ho costruito tutti e due circuiti encoder stereo, il primo con due integrati(4047- 4066)funziona discretamente bene, mentre il secondo con
    (4047-4013-4066-741)non si sente la separazione dei canali ma si accende il led stereo sul ricevitore e collegando la R6 ingresso del Ic 4066 si spegne il led stereo del ricevitore radio perchè il signal a 19khz si abbassa di ampiezza in uscita. Posso avere qualche suggerimanto per farlo funzionare bene ? tank you

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