diff --git a/README.md b/README.md index c461137..dc243d1 100644 --- a/README.md +++ b/README.md @@ -34,6 +34,7 @@ All inputs (besides the microphones) and outputs should: - expect/ deliver a nominal level of +6dBu (german TV broadcast standard, 0 dBu = 0,775 Veff) - be transformer balanced and galvanically isolated +This results in a signal flow like this: ![](docs/signal-flow.jpg) ## Status @@ -77,7 +78,7 @@ From theoretical calculations, we might need another 30 to 40 dB here, which nee TODO: Try out using the amp's feedback resistor for gain control or just use a potentiometer on the input of the next stage. -TODO: Integrate the On-Air and mute buttons +TODO: Integrate the On-Air button For long-lasting endurance of the microphone level potentiometer, we're using one with conductive plastic as resistor element (Bourns model 91). @@ -104,7 +105,7 @@ TODO: How to achieve galvanic isolation? #### Headphone Output Driver The headphone output needs a maximum output power of about 0.1 W and should put the mono signal on both stereo channels of the TRS jack. -For the first draft, we're using one LM386 audio power amplifier. +For the first draft, we're using one LM386 audio power amplifier --> way too much amplification! TODO: Check, if driving the two speakers in parallel leads to any issues (besides cutting the speaker impedance in half). diff --git a/docs/signal-flow.jpg b/docs/signal-flow.jpg new file mode 100644 index 0000000..f89e2ef Binary files /dev/null and b/docs/signal-flow.jpg differ diff --git a/docs/signal-flow.odg b/docs/signal-flow.odg new file mode 100644 index 0000000..5c6587d Binary files /dev/null and b/docs/signal-flow.odg differ diff --git a/docs/signal-flow.pdf b/docs/signal-flow.pdf new file mode 100644 index 0000000..e22deb6 Binary files /dev/null and b/docs/signal-flow.pdf differ diff --git a/docs/signal-flow.png b/docs/signal-flow.png new file mode 100644 index 0000000..3407a20 Binary files /dev/null and b/docs/signal-flow.png differ