Re-creating E-Bow effect using teensy 3.5 and an audio shield

mick

Active member
Hi everyone,

I'd like to build this device using a teensy and an audio shield, essentially re-creating the circuit as a digital one.

http://www.luigimarino.net/building/c-bow.html

c-bow-schematic.jpg

There's some very well documented details on Luigi's page. My initial idea was to simply hook up the piezo/contact mic directly to the mic input of the audio shield, and then take one of the line-out pins and hook it up to an LM386 in order to amplify the signal.

Does this make sense? Or is there more going on in the circuit that I'm missing? Luigi's circuit runs on 9V, so therefore I figured it's best to only take the part which amplifies the signal.

Any suggestions around this would be really appreciated. I've worked plenty with microcontrollers and 5/3.3V logic, but 9V analog circuits are a bit new to me.

Best,
Mickey
 
Well it appears to be a variable low pass filter and a power amp output. The LM386 hasn't been made for years, doubt you'll find one that's not a fake, perhaps a small class-D chip would be a suitable replacement?

The 100k pot setting the low-pass needs something like a 100 ohm resistor in series with it to prevent destabilizing the opamp (they can't drive capacitive loads directly).
 
yeah I got rid of most of that, simply hooking up a contact mic to the teensy audio board and a basic amplifier circuit such as below:

Screenshot 2022-07-10 185115.jpg

I based it off the datasheet of the LM386, luckily I still managed to get a few of them. Though I agree that it would have made sense to look for a different amplifier.
 
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