# Arduino based VCOs? **URL:** \ **Category:** DIY STUFF\ **Created:** [March 26, 2021, 3:06am UTC](https://lookmumnocomputer.discourse.group/t/arduino-based-vcos/3242 "2021-03-26T03:06:34Z")\ **Posts on this page:** 4\ **Page:** 2
**Author:** ![fredrik](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/fredrik/32/682_2.png) [@fredrik](https://lookmumnocomputer.discourse.group/u/fredrik)\ **Post date:** [April 14, 2021, 4:35pm UTC](https://lookmumnocomputer.discourse.group/t/arduino-based-vcos/3242/21 "2021-04-14T16:35:49Z")
To clarify, VIN should be 7-12 V and is regulated to 5 V by an onboard regulator. If you provide 5 V yourself, connect it to +5V, not VIN. See here: > [@Design glitches: Arduino Nano supply voltage](https://lookmumnocomputer.discourse.group/t/design-glitches-arduino-nano-supply-voltage/795): > > (thought I’d collect my nano supply notes in one place to make it easier to link to) A common design glitch in circuits that use an Arduino Nano is to connect regulated 5 V to the VIN pin instead of the +5V pin. This results in the Arduino running at a lower internal supply voltage, often 4 V or below, which may be a problem if the design depends on analog inputs or digital output levels. Voltages below 4.5 V are also out of spec for the 16 MHz clock used by the Nano. Details below, but TL;DR … (that’s for a Nano, but Leonardo has a similar power supply, using an NCP1117 that is similar to the LM1117 and AMS1117 regulators mentioned there, with a 1.2 V drop) The input pins have protection diodes to deal with input voltages above and below the supply rails, but they cannot handle a lot of current, so unless you have current limiting resistors on the way in, over- and undervoltages may fry them. > [@1222 Tuner VCO Module](https://lookmumnocomputer.discourse.group/t/1222-tuner-vco-module/16/47): > > The AVR chips have clamping diodes on all inputs, which keep the voltages between −0.5 V to Vcc + 0.5 V, so as long as you don’t fry the diodes, the chip will survive higher input voltages (there’s an Atmel appnote that shows how to detect zero crossings in 240 V AC with two 1M resistors and nothing else). ---
**Author:** ![AKS2346](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/aks2346/32/11458_2.png) [@AKS2346](https://lookmumnocomputer.discourse.group/u/AKS2346)\ **Post date:** [April 14, 2021, 6:01pm UTC](https://lookmumnocomputer.discourse.group/t/arduino-based-vcos/3242/22 "2021-04-14T18:01:37Z")
Fredrick, Thank you for the excellent and clear information. That’s a lot better than what I was trying to say. Appreciate it. I can say that it is possible to send CV into an Arduino and using various libraries have it act as a VCO and its been working pretty well for me! The issue has only that the Mozzi library spits out a PWM basically on its output pin that has to be integrated into an actual wave and it took me some back and forth to get a high quality signal out. Mozzi docs have a suggested resistor capacitor combination but for some reason it didn’t work for me out of the box and I had to fiddle. ---
**Author:** ![K.ostas](https://avatars.discourse-cdn.com/v4/letter/k/ed655f/32.png) [@K.ostas](https://lookmumnocomputer.discourse.group/u/K.ostas)\ **Post date:** [August 24, 2023, 8:22pm UTC](https://lookmumnocomputer.discourse.group/t/arduino-based-vcos/3242/23 "2023-08-24T20:22:42Z")
There is also [this](https://www.instructables.com/Arduino-Voltage-Controlled-Wavetable-Oscillator/) wavetable DCO. I was wondering whether anyone has tried it, or attempted to build something similar. ---
**Author:** ![K.ostas](https://avatars.discourse-cdn.com/v4/letter/k/ed655f/32.png) [@K.ostas](https://lookmumnocomputer.discourse.group/u/K.ostas)\ **Post date:** [September 4, 2023, 12:11pm UTC](https://lookmumnocomputer.discourse.group/t/arduino-based-vcos/3242/24 "2023-09-04T12:11:42Z")
And just two days after I asked, someone did build it, as per the instructables page! [Previous page](https://lookmumnocomputer.discourse.group/t/arduino-based-vcos/3242.md?page=1)