mixing and volume

Posted on Feb 5, 2014

I built the LM386 amplifier section, and it pretty much works. I purchased a five-conductor headphone jack, which passes the left and right channels through to the mono amplifier section when nothing is plugged in, but disconnects the amplifier section when a headphone plug is inserted. The only problem is that even when disco

mixing and volume
Click here to download the full size of the above Circuit.

nnected, the amplifier section still picks up a faint copy of the audio signal (from antenna effects or power supply noise ) and amplifies it. Ideally the amplifier section would be switched off entirely when a headphone plug is inserted, instead of merely disconnecting its input signal. The bad news: The portion of the circuit before the headphone jack seems able to mix three channels into two, or to control the volume, but not both. The AY-3-8913 has three separate voices: A, B, and C. I want to mix them so that A is on the left stereo channel, C is on the right channel, and a half-volume copy of B is on both channels. This job is done with a resistor network. I also want to control the output volume with a potentiometer. Below are two similar circuits for performing these tasks. Although it`s not shown here, both circuits have their L and R outputs connected to the headphone jack, which in turn is connected to the speaker amplifier section as described above. On the right is the Polish circuit  I mentioned in my last post, with a 10K stereo audio potentiometer added at the output. On the left is a circuit I found on a ZX Spectrum hacking site, also with an output potentiometer. Neither circuit included a potentiometer originally. You can probably see where this is going: the functions of mixing and attenuation conflict. Mixing works because the total resistance between A, B, or C and L or R is different for different...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Reaction Timer
    2 GHz CMOS Voltage-Controlled Oscillator with Optimal Design of Phase Noise and Power Dissipation
    3 channel audio mixer
    avr programmer how to make
    morning light activated alarm circuit
    4 X 15 Watt power amplifier
    Mains operated LED night lamp
    time delay relay circuit
    Applications of SR Drive Systems on Electric Vehicles
    Electronic Torricelli Barometer
    Beeping Down Counter Circuit