Forgive the length of this! My project includes Teensy 4.0, Audio Shield and a 5 watt amp. Sound is capture by a pair of TENS mics and provides a low cost hearing aid alternative using a bone-conduction headset. I've included functions to self-administer an actual hearing test, create an Audiogram and process the sound through an equalizer function to match the audiogram, along with other functions to tweak things for improved speech comprehension, etc. The program is controlled by a 4 button interface and OLED display so that no other device (like a computer or smartphone) is required for programming. This is all open source and I'll have a website up shortly. The TENS mics are on modules that provide ADC conversion and a preamp, which means they feed happily into the Audio Shield's line-in L/R. What I want to add is the use of Bluetooth so that the user can also use the device to listen to music/audio-books, etc. This actually works now by simply physically switching between the mic and Bluetooth inputs, but I would like to be able use both simultaneously and add the ability to adjust the balance between the signals. Ideally, someone makes a cute little module that has line-level audio 4 in and 2 out that can be controlled digitally by the Teensy. Searching has not been successful so far. Anyone know of such a thing, or suggest an alternative solution??? Thanks!
Mixer module to provide 4 in 2 out input to Audio Shield???
- Thread starter robedney
- Start date
houtson
Well-known member
may be a bit more than you need with 6 ins and 8 outs but worth checking if your looking for something pre-built and relatively cheap
cheers, Paul
cheers, Paul
I haven't seen it as a ready made module, but a 3xstereo in -> 1 stereo out mixer can be built using the PT2258 6 channel I2C volume controller.
I have it as a part of another project, however, i haven't gotten to test it in action yet. Here is the snippet from the schematic:
This version is for 9VDC supply. It will work with 5V, i'd swap the TL074 for TLC2274 (rail-to-rail) for 5V use.
Both chips are available in through-hole DIP packages, it could be built even on a perf board.
I have it as a part of another project, however, i haven't gotten to test it in action yet. Here is the snippet from the schematic:
This version is for 9VDC supply. It will work with 5V, i'd swap the TL074 for TLC2274 (rail-to-rail) for 5V use.
Both chips are available in through-hole DIP packages, it could be built even on a perf board.
Yes I have, but I'm trying to keep the package as small as possible. Just for fun, the solution I'm working on now just feeds both inputs (Bluetooth and Mics) to audio line-in. I get software control by using a couple of transistors as switches to power one up and the other down. That allows the user to be listening the Bluetooth but instantly switch to hearing aid mode if needed. By having a couple of functions to do this, I can adjust the volume as needed to balance out the input levels depending on input selection.