Passive mixer question

[SteveyD]

Jan,

In the MicroRDS user manual;

Figure 5.2.1
Simple Passive Mixer.

Is the resistor value of 1K5 on the Audio/MPX signal for a mono audio input?

How would you handle a Stereo Audio input for this circuit?

[Jan]

For stereo audio use two inputs instead of one and place two 3k3 resistors. So there will be three inputs and three resistors total connected to the sum point.

Code: [Select]

Left  o--[===]---------\     2x 3k3
                        \
Right o--[===]-----------*---->
                        /
RDS   o--[===]---------/     15k
Of course you will broadcast in mono as there's no stereo encoder.