[ $5 ] DIY eurorack modular synth Clock SYNC LFO with Arduino / fast PWM frequency change

My 12th original eurorack modular synth DIY projects with arduino.
Clock sync LFO module , cheap and simple circuit.
The output circuit has been simplified by changing the PWM frequency of Arduino to a higher speed.
The PWM frequency is changed by directly controlling the register of the microcontroller.
working documents ( Source code )
note.com/solde...
Please support me to continue projects.
/ hagiwo
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My other DIY modular synth movie.
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[@IrregularShed]

Your modules are so inspirational, thank you for sharing them 🙇‍♂️

[@sonicatelierberlin6226]

It's done! excellent work, thanks to share it, I made mine with Eagle, if you want I can send you the files and you can put on your website to share.

[@HAGIWO]

correction: 3:39 60kHz-> 50kHz 6:15 picture is different

[@kristofkelemen2547]

Great work! I would like to ask that I want to use the clock input with the gate out output of a Behringer Td3. Behringer's gate output voltage is 0V and 12V. Can i use it or I have to change something? Thanks!!!

[@HAGIWO]

I think it will work with a 12V gate signal. All input/output circuits of the module have overvoltage protection circuits, so they will not be broken by 12V.

[@LAURISDIYCHANNELTV]

Hell yeah!

[@blackcloudstofollow]

I wonder; could you have two instances of this on one arduino nano? there is enough pins but is there another reason why it would or wouldn't be possible?

[@zoltorgrind]

Hello, please tell me how i can modify your circuit to use 5 din midi clock. I have a polyvox synthesizer and a midi kit is installed there, but modulation synchronization is impossible. I want to build your circuit to use it instead of a polyvox lfo generator, but I need to take sync from 5 din midi. Thank you.

[@trueboubou5936]

Great channel! Thank you very much for all the good stuff! I've just tried the schematic/code and was able to double the PWM frequency by using FAST PWM mode. only 2 lines had to be changed: TCCR1A = 0b00100011; TCCR1B = 0b00011001; Any reason you didn't use FAST PWM mode? Worked pretty well for me. I was able to lower the capacity of the lowpass filter's capacitor even more.. (to 0.1uf). Anyway, have a good one! Looking forward to your next project :)

[@lecheng-synth]

こんにちはhagiwo、私のpwm出力インタフェース上のRCフィルタ回路は、ご提示のような回路では、うまくフィルタリングできません。得られた振動波形は多くのバリがあり、あなたのビデオ上の平滑さがありません。これはなぜでしょうか。 Hello Hagiwo, the RC filtering circuit on my PWM output interface cannot filter well on the circuit you showed. The resulting oscillation waveform has many burrs and is not as smooth as in your video. Why is this?

[@HAGIWO]

The PWM frequency may be too low or the RC value may be incorrect. Is the PWM frequency greater than 50 kHz? The standard PWM frequency for the Arduino is 980 Hz, but this module clocks up to 50 kHz. Is the RC value correct?

[@lecheng-synth]

Thank you for your reply! My RC circuit is correct, and I suspect what may be causing the insufficient frequency of the PWM

[@-______-______-]

@@lecheng-synth What was it?

[@-______-______-]

If I wanted to give it the clock from my DAW, how do I connect it? Do I need a midi to cv converter?

[@HAGIWO]

Yes, a MIDI to CV module is required.

[@-______-______-]

@@HAGIWO many thanks for the reply.

[@hughman8597]

This is so incredible cool ! For me as a guy with almost no money a chance to have a good modular with a lot of cool modules ! Now you have to put a Fancy Name like "cookable influence" *hust* ;) on it (please don´t do that) and sell it for 349$ and you are a made man :) .

[@Sarahbuildsstepsequencers]

Nice! Very versatile! Haven’t seen such a module. Excellent demo. Thanks!

[@asciisynth]

You got a really clean output signal from PWM. Great module.

[@sachagirard561]

Would it be difficult to put a small display like the 0.96" to visualize the BPM number ?

[@HAGIWO]

Adding a display is not difficult. However, there are concerns about clock output delays due to display refreshes.

[@imnobody303]

Should not you consider to add an OP-amp for the output ? It could be a problem without because of the led, and you put multiple passive output. And you didn't have put protection circuit on the output.

[@HAGIWO]

thank you! Annotations have been added to the document.

[@compuzik]

Great Module, thanks for sharing. One banal question, are the Potis lin or log?

[@HAGIWO]

it is lin curve pot.Thank you!

[@raziel06001]

Nice ! Great one ! Just made it, I saw on your working documents that you're saying the pwm frequency should be around 50000Hz, but using your code is only at 1000Hz. As someone said earlier, by changing the register to fast pwm it works great. I also modify it a bit to have a secondary output using timer 2, which is only 8 bits, not really accurate but for some application is fine, and anyway I made this output to be square all the time, still in sync with the main. The only thing is that I can't get the clock synth working yet, not sure why, I'll look at it soon Thanks for sharing !

[@lecheng-synth]

Hello, I am also thinking about why my same RC filter cannot filter out the PWM signal, so I saw many burrs on the oscilloscope. This indicates that my PWM may only be 1000Hz and not high enough. If it runs at 50khz, it can be filtered, right? So why did Hagiwo's high-frequency PWM encoding not take effect?

[@davzmusic]

In the future you could probably try a smoothed random cv / Perlin noise implementation to modulate stuff smoothly like the Perlin noise seen in Vital VST or Serum's chaos

[@nugravityzm]

Next video 808 style Gate Sequencer + Arduino - PLEASE!!!

[@sonicatelierberlin6226]

hi, wonderfull work, I want to build one, only one question, wich diode is the Schottky?, I can not see the reference in the schematics. Thanks in advance.

[@HAGIWO]

I recommend Schottky with a forward voltage of 0.4V or less. I am using BAT43.thx!

[@sonicatelierberlin6226]

@@HAGIWO thanks for your answer, I did buy the BAT43, another questions more, in the Out there is a capacitor with the value 4.7 uF, is this capacitor a bipolar electrolitic or tantalum? my highest value in ceramic is 1uF and 10uF in Tantalum, or can I use a normal eletrolitic capacitor with this value? thanks in advance

[@HAGIWO]

@@sonicatelierberlin6226 I use ceramic capacitor.But any type of capacitor is OK.

[@anllume]

and it works! thank you so much for making this affordable, accessible, inspiring and fun! keep up the good work!.

[@soerenraudonis]

mutch apreciation for the genius simplicity of your code and circuits

[@romanopekushin3099]

I have never seen such a generator with such capabilities. I can certainly be wrong. A powerful tool. Everything will work out for you!

[@UnauthorisedService]

Super modulator 👏. It is built 👍

[@peterhutt4807]

pretty well explained, thanks

[@finonomastropiero4261]

Awesome

[@imnobody303]

I'm trying to look at your code but I see some stranges things : first, OCR1A is for pin 9 but you only use pin 10 (OCR1B), TCCR1A and TCCR1B must be set only once at setup, not every frame. And if I do like in your schematic I have issue with the output, not smooth. I'll comment after fixed that. I'll add a switch to select from inner or external clock, because if we put an external clock slower than 8 sec it will then switch to internal clock automatically.

[@imnobody303]

My first attempt with good results : setting timer freq frq = 62500. Then the registers TCCR1A = 0b00100011; TCCR1B = 0b00010001; for fast PWM 8 bits without correction at 62500Hz. And FlexiTimer2::set(5, 2.0 / frq, timer_count) to be sync with the PWM output frequency. And I'm able to reduce the output capacitor to as low a 2.2uF even 1uF. I also have to remove the count = 0 line after ext_count = 0 else it cancel counting and make artifact in the output signal.

[@HAGIWO]

For PWM acceleration, I referred to the linked code. It seems to work fine in my environment.blog.kts.jp.net/arduino-pwm-change-freq/

[@imnobody303]

@@HAGIWO Interesting, It seems I could increase the frq 800000 to 16000000.

[@Evgen-gf5eu]

Hi friend, already assembled sync LFO according your manual, at it is working, thank you!

[@Evgen-gf5eu]

Syc from external clock is fine

[@-______-______-]

@@Evgen-gf5euHow did you connect the external clock, via midi to cv converter?

[@Evgen-gf5eu]

@@-______-______- no i use another DIY clock module

[@leandroconejo]

Also worked without external clock sync ? tnx

[@Evgen-gf5eu]

@@leandroconejo yes, because it is LFO