Electronic schematics, circuit designs
One transistor audio mixer
The simpliest audio mixer schematic on the net. It has only one transistor and can support as many audio signal as you can afford. BC109C is a very cheap transistor and with a few resistor and capacitors you can build quickly a simple audio mixer that you can use in your pirate radio or wherever you want, imagination is the final frontier. Please keep in mind not to use higher voltages than 22V as a power supply for this audio mixer.
Stereo encoder 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 coder has a better design than this stereo circuit encoder but the principles are the same.
Stereo Encoder schematic components:
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Audio limiter circuit schematic
This audio limiter circuit is easy to build, works with BA741 8pins or 4pins so pay attention and uses a symmetrical power supply. When the audio input level is between 20mV and 20V the output will be a constant 25mV signal. Audio limiters can be used in a transmitter schematic or in any circuit you need a constant audio level.
Audio limiter components:
R1 = 100K
R2 = 1K
R3 = 1M
R4 = 68K
R5 = 10K
C1 = 10uF
C2 = 680nF
T1 = BFW11
T2 = BC173C
IC = BA741
