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Thread: Teensy audio board or teensy prop shield LC for my project?

  1. #1
    Junior Member
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    Feb 2018
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    Teensy audio board or teensy prop shield LC for my project?

    Okay I spent hours on making my old thread, but it logged me out, had to relog and lost everything I wrote, so here is the tl;dr, and will answer question (probably would've with my other one.)

    I am wanting to build a voice amplifier for my 3m half face respirator, I found 3d models of 3m 6092x series cartridge on thingiverse, I plan to modify for my needs, and use to house all these components if space is willing.

    ** - optional if not possible

    If I went with audio board.
    Teensy 4.0
    electret microphone
    lm358 or 386 (and whatever else is needed for the circuit)
    2 watt 8 ohm speaker
    3.7 @ 1a+ lipo battery
    adafruit powerboost 500 charger
    bluetooth module**
    sd card (relation if bluetooth is supported)**
    10k potentiometer for volume output control

    if I went with prop shield LC.
    Teensy 3.2-3.6
    electret microphone
    2 watt 8 ohm speaker
    3.7 @ 1a+ lipo battery
    adafruit powerboost 500 charger
    bluetooth module or esp32**
    sd card module (relation if bluetooth is supported)**
    10k potentiometer for volume output control

    reason for bluetooth is if I can use it to play audio files I have stored on the serial memory or sd card** on the prop shield or audio board.

    between choosing either board, parts list isn't that much different. what I am listing is what I intend to buy which ever board I decide on, if I am missing any core components, or if I should consider changing components, please let me know, and I appreciate taking time out of your day to read my thread. Thanks in advance.

  2. #2
    Senior Member+ MichaelMeissner's Avatar
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    This is one of those things where the answer is it depends.

    Note the prop shield is mono only. It has a built-in amplifier so that you can hook up a single 2watt 4/8ohm speaker directly. It has an 8 megabyte flash memory as part of the prop shield. It was designed for the Teensy 3.2. If you want to use the larger 3.5 or 3.6, you will need to run a wire from the A21 pin to the pin on the back of the prop shield to connect the audio output. While there is a way to do audio output without a audio shield on the Teensy 4.0/4.1 (using MQS) it will interfere with using SPI devices like displays. Note, there is no microphone input on the prop shield.

    The audio shield can handle stereo output. It has a headphone jack for a direct connection. For the speakers, you would need to add an appropriate amplifier between the line out pins and the speakers. It does have a micro-SD card built-in. You can solder a 16 megabyte flash memory chip for permanent storage in addition to the micro-SD card. The soldering involves surface mount soldering. The audio shield has support for adding an electret microphone directly. There is a co-processor on the audio shield, but I don't know what sorts of things it does. If you go the audio shield route, be sure to order the right board. Revision C is for the Teensy 3.2, 3.5, and 3.6. Revision D is for the Teensy 4.0 and 4.1.

    In terms of lipo batteries, I like the Adafruit Teensy -> Featherwing adapter, which includes a lipo charger. I like it because it is a lot sturdier than the boards where you have to solder in the lipo plug. Note, the featherwing adapter was designed for the Teensy 3.2. If you are mounting a Teensy 3.5, 3.6, or 4.1, you need to add some risers to mount the Teensy up higher to clear the lipo plug. And there are a few tweaks you may need to do for the Teensy 4.0/4.1 boards if you use the featherwing to mount other feather boards.

    If you go with the Teensy 3.6 or 4.1, it has a second USB port that acts as a USB host, and you can connect various USB devices. I've seen posts about people connecting bluetooth devices to it, but I've not done it myself, so I don't know what sort of restrictions there are.

  3. #3
    Senior Member
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    May 2015
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    USA
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    705
    Possibly a i2s MEMs microphone for input into the teensy?

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