Teensy 4.0 600MHz ARM Cortex M-7 MCU - ideal for digital MCU based theremin?

Posted: 9/8/2021 5:49:00 AM
andreyrogatkin

Joined: 1/27/2021

Hi, Buggins! Please check your private messages. I can't get in touch with you . 

Posted: 9/15/2021 7:11:37 PM
Buggins

From: Theremin Motherland

Joined: 3/16/2017

Created teensytheremin organization and theremin project on github.

Will put all schematics and firmware there.


Created github pages site with description of project - for documentation, build instructions, etc.

Posted: 10/16/2021 3:55:23 AM
Buggins

From: Theremin Motherland

Joined: 3/16/2017

Project pages updated

Published Teensy 4.1 Theremin Main Board KiCAD project and schematics in PDF

Published Teensy 4.1 Theremin Display and Controls Board KiCAD project and schematics in PDF

Previous LT1711 comparator based oscillator is unstable (starts oscillating at high frequency) when hand touches antenna.

New candidate for oscillator is described in this post


TODO: BOM and soldering instructions

Posted: 10/22/2021 1:57:50 PM
Flounderguts

Joined: 10/24/2020

Good article on mcu oscillators...

not sure if it will help, but I thought of it when I was reading this...

https://en.wikipedia.org/wiki/Numerically-controlled_oscillator?wprov=sfla1

Posted: 10/22/2021 6:03:43 PM
Buggins

From: Theremin Motherland

Joined: 3/16/2017


Good article on mcu oscillators...

not sure if it will help, but I thought of it when I was reading this...


It might be useful for FPGA theremin implementation - e.g. for generation of reference frequency in phase shift or pll based sensors.


Not for usual oscillator.

Posted: 10/22/2021 6:16:16 PM
Buggins

From: Theremin Motherland

Joined: 3/16/2017

Unusual current sensing oscillator: details in this post


LTSpice model file is available on GitHub


SN74LVC2GU04 and other component models can be downloaded here

UPD: adding several output buffers in parallel provides bigger drive current. With 2 additional inverters in parallel with existing one gives 400Vpp on antenna.

LVC2GU04 model is a bit strange. Sometimes, provides empty signals - neither current nor voltage is visible in components connected with U04.
Does someone know where to find good lvc unbuffered inverter model?

Capacitor added to R7/R8 reference voltage sometimes helps.


Posted: 11/10/2021 11:41:19 AM
Buggins

From: Theremin Motherland

Joined: 3/16/2017

New candidate for digital theremin sensor oscillator. Details in this post.

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