# Verified Stripboard Layouts!

**URL:** <https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81>\
**Category:** DIY STUFF\
**Created:** [January 22, 2020, 6:51pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81 "2020-01-22T18:51:43Z")\
**Posts on this page:** 20\
**Page:** 25

<div class="post-metadata">

**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\
**Post date:** [October 26, 2022, 8:32pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/497 "2022-10-26T20:32:19Z")

</div>

“Bipolar” and “nonpolarized” mean essentially the same thing, the opposite of “polarized”. Usually “bipolar” refers to an electrolytic that is basically two polarized electrolytics back to back in the same package (and you can use two polarized electrolytics back to back as a substitute for a bipolar), but the point is to use a capacitor that isn’t polarized; whether that’s ceramic (always nonpolarized) or film (always nonpolarized) or electrolytic (either, but you want nonpolarized) isn’t that big a deal. Though film might perform better than ceramic in this case.

---

<div class="post-metadata">

**Author:** ![peternoya](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/peternoya/32/13307_2.png) [@peternoya](https://lookmumnocomputer.discourse.group/u/peternoya)\
**Post date:** [October 27, 2022, 3:54am UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/498 "2022-10-27T03:54:13Z")

</div>

Ronnberg himself uses film or ~~_bipolar_~~ **polarized** electrolytic in his build. He doesn’t say anything about the non-polarized on his page.

Note the white stripe that indicates the negative side of the capacitor in this image:

 ![20](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/8/7/871985bc3bcc6d005a3e57df5fa6be2384bc6013.jpeg)

And Here, how to properly connect the ~~_bipolar_~~ **polarized** electrolytic:  
 ![24](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/2/e/2e609c79bf5227ab335810b0c6701abfbacc90fb.png)

Following @Dud layout you will also be able to notice the correct polarization:

 ![triple-lfo-by-sound-bender](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/3/8/3857f61b73cb0435d097a5730b9181e4d15b61db.png)

And as said by @analogoutput, using non-polarized electrolytics will not make any difference.

Link to the original article:  
[https://web.archive.org/web/20191220104258/http://familjenronnberg.se/~niklas/diy/eurorack/lfo/](https://web.archive.org/web/20191220104258/http://familjenronnberg.se/~niklas/diy/eurorack/lfo/)

---

<div class="post-metadata">

**Author:** ![Bertindo](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/bertindo/32/22908_2.png) [@Bertindo](https://lookmumnocomputer.discourse.group/u/Bertindo)\
**Post date:** [October 27, 2022, 11:17am UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/499 "2022-10-27T11:17:40Z")

</div>

Thanks @analogoutput!  
as always your answer is at first quite a puzzle for a beginner like me, but after some puzzling and research that makes totally sense. Thanks for stimulating my learning curve!  
I’ll experiment with some polyester Film caps I have.

---

<div class="post-metadata">

**Author:** ![Bertindo](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/bertindo/32/22908_2.png) [@Bertindo](https://lookmumnocomputer.discourse.group/u/Bertindo)\
**Post date:** [October 27, 2022, 11:18am UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/500 "2022-10-27T11:18:16Z")

</div>

I did not notice the blue film cap…  
thnx for pointing out!

---

<div class="post-metadata">

**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\
**Post date:** [October 27, 2022, 11:59am UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/501 "2022-10-27T11:59:31Z")

</div>

> [@peternoya](#):
>
> Ronnberg himself uses film or bipolar electrolytic in his build. He doesn’t say anything about the non-polarized on his page.

The conventional terminology is that “bipolar” electrolytics are synonymous with “nonpolarized” electrolytics, as differentiated from “polarized” electrolytics. Bipolar or nonpolarized electrolytics have no white stripe. So it does appear a polarized electrolytic was used. For use with an AC voltage I guess you can get away with it, but it would not be my preference.

---

<div class="post-metadata">

**Author:** ![peternoya](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/peternoya/32/13307_2.png) [@peternoya](https://lookmumnocomputer.discourse.group/u/peternoya)\
**Post date:** [October 27, 2022, 5:34pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/502 "2022-10-27T17:34:01Z")

</div>

> [@analogoutput](#):
>
> “Bipolar” and “nonpolarized” mean essentially the same thing, the opposite of “polarized”.

You were very clear on this issue.  
I wonder why the hell I still made the same mistake…  
Thanks for correcting me.

> [@analogoutput](#):
>
> For use with an AC voltage I guess you can get away with it, but it would not be my preference.

Taking this opportunity I would like to ask:  
Which ideal option? Since film caps with high capacitance values have a very large package because they are usually manufactured for higher voltages.  
I wish I had a good option that didn’t take up so much space on the board layout.

---

<div class="post-metadata">

**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\
**Post date:** [October 27, 2022, 5:43pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/503 "2022-10-27T17:43:36Z")

</div>

What capacitance? Above 1uF bipolar electrolytics are probably best.

---

<div class="post-metadata">

**Author:** ![peternoya](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/peternoya/32/13307_2.png) [@peternoya](https://lookmumnocomputer.discourse.group/u/peternoya)\
**Post date:** [October 27, 2022, 6:13pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/504 "2022-10-27T18:13:07Z")

</div>

Yes, that answers my question. Thank you!

I would like to have your opinion on this:

> [@analogoutput](#):
>
> you can use two polarized electrolytics back to back as a substitute for a bipolar

It’s safe? Or does it have any disadvantage (or recommended adptations in circuit) compared to the ready made types?  
I had already researched this subject before, there are many disagreements but I didn’t find anything conclusive.

---

<div class="post-metadata">

**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\
**Post date:** [October 27, 2022, 7:38pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/505 "2022-10-27T19:38:42Z")

</div>

As I understand (I’m no expert) it’s safe and it works, the main disadvantage being footprint size.

---

<div class="post-metadata">

**Author:** ![peternoya](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/peternoya/32/13307_2.png) [@peternoya](https://lookmumnocomputer.discourse.group/u/peternoya)\
**Post date:** [October 27, 2022, 8:47pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/506 "2022-10-27T20:47:39Z")

</div>

Glad to know that. Thank’s for your time.

---

<div class="post-metadata">

**Author:** ![Bertindo](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/bertindo/32/22908_2.png) [@Bertindo](https://lookmumnocomputer.discourse.group/u/Bertindo)\
**Post date:** [November 7, 2022, 10:37am UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/507 "2022-11-07T10:37:45Z")

</div>

I am in the process of laying out a pcb for the Triple Sloth version.

> **[Triple Sloth — Nonlinearcircuits](https://www.nonlinearcircuits.com/modules/p/triple-sloth)**
>
> Description/Usage 8hp This module contains 3 Sloth chaos circuits. Each one runs at a different rate; Torpor takes approx. 15-30 seconds to travel around 2 strange attractors, Apathy takes 60-90 seconds and Inertia takes 30-40 minutes. There...

 ![triple sloth](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/8/f/8fa1f8389d87c644bdfafe8c22d3c992ed06b23d.jpeg)

Am I correct to think that, since it is mostly op-amp, these circuits should also work fine with +/-15V?  
Or should is foresee an LM7812/7912 optionally to be on the safe side?

---

<div class="post-metadata">

**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\
**Post date:** [November 7, 2022, 12:39pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/508 "2022-11-07T12:39:38Z")

</div>

I’d think ±15 V would be fine. You might want to adjust output levels. (I’m puzzled as to why some outputs (y and z for Inertia and Apathy) have voltage dividers while the rest don’t.)

---

<div class="post-metadata">

**Author:** ![savt22](https://avatars.discourse-cdn.com/v4/letter/s/ad7895/32.png) [@savt22](https://lookmumnocomputer.discourse.group/u/savt22)\
**Post date:** [January 3, 2023, 1:44pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/509 "2023-01-03T13:44:00Z")

</div>

![AS3364 Quad VCA](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/0/d/0d1ed6dc170181cd10904524a8e8188c3923337d.png)

Simple AS3364 Quad VCA board.

 ![EnvGen seperate controls](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/c/0/c08e0b8a82d3886dfca1f9239a425c6e08030462.png)

Dual ADSR with separate controls for each envelope generator.

 ![EnvGen shared controls](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/1/e/1e13ceb81677420b3af03c1664702a0b59a939c4.png)

Dual ADSR with controls shared between each envelope generator.

 ![Pi Pico DCO, Oscillators, ADSR, VCA](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/e/1/e1e1b82a6899cee6027ab16eccc0c58a1d802a17.jpeg)

Stripboard layout for core building blocks of a basic polyphonic build based on Polykit’s Pi Pico DCO. Could probably be squeezed into a 4-voice module without too much issue, lots of options for modding. Hopefully useful for someone out there.

---

<div class="post-metadata">

**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\
**Post date:** [January 3, 2023, 4:10pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/510 "2023-01-03T16:10:08Z")

</div>

For the Engen8 chip, with some few components, you have possibility to easy add the “Time duration”, “Loop mod”, “Gate Loop”, “Hold” … fonctions of the chip.

I built one and these simple additions are really very useful 🙂  
if you want to take a look

 ![1157+MINI+ADSR](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/7/1/71882f04ab8f5625bf4a70dd1d3de2dfc12624ab.jpeg)

> [@1157 MINI ADSR Module](https://lookmumnocomputer.discourse.group/t/1157-mini-adsr-module/359):
>
> This topic is made for the 1157 MINI ADSR which went up today! the Schematic and Bill of materials are available over here :- ill work on getting the other usual stuff for this module completed over the weekend! a simple version on stripboard and what not.

---

<div class="post-metadata">

**Author:** ![savt22](https://avatars.discourse-cdn.com/v4/letter/s/ad7895/32.png) [@savt22](https://lookmumnocomputer.discourse.group/u/savt22)\
**Post date:** [January 3, 2023, 4:46pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/511 "2023-01-03T16:46:31Z")

</div>

That’s definitely a good point! I didn’t want to include them for myself but could easily add them to the layout above. Will add them in and post something in the unverified lounge.

---

<div class="post-metadata">

**Author:** ![OneLove](https://avatars.discourse-cdn.com/v4/letter/o/eada6e/32.png) [@OneLove](https://lookmumnocomputer.discourse.group/u/OneLove)\
**Post date:** [January 3, 2023, 7:01pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/512 "2023-01-03T19:01:23Z")

</div>

Hi, I made a dual VCA as per this layout, so can confirm verified

> **[LM13700 dual VCA](https://knopslmodular.design.blog/2022/04/04/lm13700-dual-vca/)**
>
> This one is a version of benjiaos VCA, which in turn if a version of juanito moores VCA. I added a bit here and left out a bit there. I hope you like it. Two VCAs behind one gigantic faceplate A vi…

 ![img_20220518_192243](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/b/4/b464b379a422002e9bfcaba6fb9ca795f4c08ced.png)

---

<div class="post-metadata">

**Author:** ![AriaSalvatrice](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/ariasalvatrice/32/28804_2.png) [@AriaSalvatrice](https://lookmumnocomputer.discourse.group/u/AriaSalvatrice)\
**Post date:** [January 8, 2023, 10:11am UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/513 "2023-01-08T10:11:15Z")

</div>

Just finished making this little white noise daughterboard for a bigger S&H kosmo module build.

It’s 99% based on a @jkb design (itself based on a classic circuit), but with a cheaper op amp because I’m not dropping a whole euro on a chip. I like to split builds across multiple boards for easier debugging. No warranties, try it at home if you like to live dangerously.

Original project: [GitHub - polykit/kosmo-sample-and-hold: Schematics and PCB layout for a sample&hold / noise module in Kosmo format](https://github.com/polykit/kosmo-sample-and-hold/)

 ![white noise](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/c/d/cd70a870656afbf3997f47ef4807a787a7786cc0.jpeg)

---

<div class="post-metadata">

**Author:** ![savt22](https://avatars.discourse-cdn.com/v4/letter/s/ad7895/32.png) [@savt22](https://lookmumnocomputer.discourse.group/u/savt22)\
**Post date:** [June 4, 2023, 8:55pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/514 "2023-06-04T20:55:47Z")

</div>

HAGIWO Generative Sequencer, built and verified. Very cool module…

 ![Hagiwo random](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/1/7/17bbb0e6a88c08eddf9a83b666720986617b8cca.jpeg)

---

<div class="post-metadata">

**Author:** ![Synthlurker](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/synthlurker/32/21635_2.png) [@Synthlurker](https://lookmumnocomputer.discourse.group/u/Synthlurker)\
**Post date:** [June 23, 2023, 7:51pm UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/515 "2023-06-23T19:51:40Z")

</div>

The Atmega String Synth with MIDI input, built and therefore verified.

 ![Solina_atmega](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/a/f/afd1ee947e1c3d182be6fd749acbc3de5850eed5.png)  
Also here is the code that is very hard to find/get:

```auto
/* Arduino Synth from
  https://janostman.wordpress.com/2016/01/15/how-to-build-your-very-own-string-synth/
*/

/* Original code by Jan Ostman, Modified by Dave Field of Take The Moon
 *  
        https://moroccodave.com/
        https://takethemoon.com/
    
    Modifications are licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. 
    To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/.
        
    MODS:
    *****

    1. Keyboard port scanning removed - this version is MIDI-only
    2. Potentiometer inputs assigned to lower analog pins for ATMega328 compatibility
    3. DIP switch on digital pins 6, 7, 8, 9 added to allow MIDI channel selection
    4. MIDI handler re-written to use stock MIDI library and to be channel-aware
    5. Any resulting redundant code and variables removed

*/

#include <MIDI.h>

#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif

const unsigned char PS_2 = (1 << ADPS0);;
const unsigned char PS_4 = (1 << ADPS1);
const unsigned char PS_8 = (1 << ADPS1) | (1 << ADPS0);
const unsigned char PS_16 = (1 << ADPS2);
const unsigned char PS_32 = (1 << ADPS2) | (1 << ADPS0);
const unsigned char PS_64 = (1 << ADPS2) | (1 << ADPS1);
const unsigned char PS_128 = (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);

uint32_t NOTES[12] = {208065 >> 2, 220472 >> 2, 233516 >> 2, 247514 >> 2, 262149 >> 2, 277738 >> 2,
                      294281 >> 2, 311779 >> 2, 330390 >> 2, 349956 >> 2, 370794 >> 2, 392746 >> 2
                     };

const uint8_t ATTrates[32] = {
  1, 2, 3, 4, 5, 8, 12, 20, 32, 37, 43, 51, 64, 85, 128, 255, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
  0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};

const uint8_t RELrates[32] = {
  1, 2, 3, 4, 5, 8, 12, 20, 32, 37, 43, 51, 64, 85, 128, 255, 255, 128, 85, 64, 51, 43, 37, 32,
  20, 12, 8, 5, 4, 3, 2, 1
};

const uint8_t sinetable[256] PROGMEM = {
  127, 130, 133, 136, 139, 143, 146, 149, 152, 155, 158, 161, 164, 167, 170, 173, 176, 178,
  181, 184, 187, 190, 192, 195, 198, 200, 203, 205, 208, 210, 212, 215, 217, 219, 221,
  223, 225, 227, 229, 231, 233, 234, 236, 238, 239, 240,
  242, 243, 244, 245, 247, 248, 249, 249, 250, 251, 252, 252, 253, 253, 253, 254, 254, 254,
  254, 254, 254, 254, 253, 253, 253, 252, 252, 251, 250, 249, 249, 248, 247, 245, 244,
  243, 242, 240, 239, 238, 236, 234, 233, 231, 229, 227, 225, 223,
  221, 219, 217, 215, 212, 210, 208, 205, 203, 200, 198, 195, 192, 190, 187, 184, 181, 178,
  176, 173, 170, 167, 164, 161, 158, 155, 152, 149, 146, 143, 139, 136, 133, 130, 127,
  124, 121, 118, 115, 111, 108, 105, 102, 99, 96, 93, 90, 87, 84, 81, 78,
  76, 73, 70, 67, 64, 62, 59, 56, 54, 51, 49, 46, 44, 42, 39, 37, 35, 33, 31, 29, 27, 25, 23, 21,
  20, 18, 16, 15, 14, 12, 11, 10, 9, 7, 6, 5, 5, 4, 3, 2, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
  2, 2, 3, 4, 5, 5, 6, 7, 9, 10, 11, 12, 14, 15, 16, 18, 20, 21, 23, 25, 27, 29, 31,
  33, 35, 37, 39, 42, 44, 46, 49, 51, 54, 56, 59, 62, 64, 67, 70, 73, 76, 78, 81, 84, 87, 90, 93,
  96, 99, 102, 105, 108, 111, 115, 118, 121, 124
};

volatile uint8_t lfocounter;
volatile uint8_t lfocounter2;
volatile uint16_t lfoval;
volatile uint16_t lfoval2;
volatile uint8_t GATED = 1;
uint8_t OSCNOTES[4];
int16_t volume = 0;
uint8_t envcnt = 10;

//-------- Synth parameters --------------
uint32_t FREQ[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; //DCO pitch
volatile uint32_t DETUNE = 0; //Osc spread or detune
volatile uint16_t LFO = 32; //Lfo rate 0-255
volatile uint8_t VCA = 255; //VCA level 0-255
volatile uint8_t ATTACK = 1; // ENV Attack rate 0-255
volatile uint8_t RELEASE = 1; // ENV Release rate 0-255
volatile uint8_t ENVELOPE = 0; // ENV Shape
volatile uint8_t TRIG = 0; //MIDItrig 1=note ON
volatile int16_t MOD; //MODwheel
volatile int16_t BENDoffset; //Pitchbend center
volatile uint32_t olddetune;
uint32_t DCOPH[16];
uint8_t integrators[16];
uint8_t delayline[256];
volatile uint8_t writepointer;
volatile uint8_t PHASERMIX;
uint8_t DCO;
int16_t ENV;

/* --------- MIDI ----------- */
/* DIP Switch Setting = Channel (1=ON, 0=OFF)
    0000 = 1 0001 = 2 0010 = 3 0011 = 4
    0100 = 5 0101 = 6 0110 = 7 0111 = 8
    1000 = 9 1001 = 10 1010 = 11 1011 = 12
    1100 = 13 1101 = 14 1110 = 15 1111 = 16

DIP Switch Pins */
#define DIP_SW1 5
#define DIP_SW2 6
#define DIP_SW3 7
#define DIP_SW4 8
MIDI_CREATE_DEFAULT_INSTANCE();
byte MIDI_CHANNEL = 1;

/*

   INITIALISE

*/
void setup() {
  
  //PWM and GATE outputs
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
   
  // Set up Timer 1 to send a sample every interrupt.
  cli();
  // Set CTC mode
  // Have to set OCR1A *after*, otherwise it gets reset to 0!
  TCCR1B = (TCCR1B & ~_BV(WGM13)) | _BV(WGM12);
  TCCR1A = TCCR1A & ~(_BV(WGM11) | _BV(WGM10));
  // No prescaler
  TCCR1B = (TCCR1B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);
  // Set the compare register (OCR1A).
  // OCR1A is a 16-bit register, so we have to do this with interrupts disabled to be safe.
  OCR1A = 758; //F_CPU / SAMPLE_RATE;
  // Enable interrupt when TCNT1 == OCR1A
  TIMSK1 |= _BV(OCIE1A);
  //set timer0 interrupt at 61Hz
  TCCR0A = 0;// set entire TCCR0A register to 0
  TCCR0B = 0;// same for TCCR0B
  TCNT0 = 0;//initialize counter value to 0
  // set compare match register for 62hz increments
  OCR0A = 255;// = 61Hz
  // turn on CTC mode
  TCCR0A |= (1 << WGM01);
  // Set CS01 and CS00 bits for prescaler 1024
  TCCR0B |= (1 << CS02) | (0 << CS01) | (1 << CS00); //1024 prescaler
  // enable timer compare interrupt
  TIMSK0 |= (1 << OCIE0A);
  sei();
  // Set baud rate to 31,250. Requires modification if clock speed is not 16MHz.
  UBRR0H = ((F_CPU / 16 + 31250 / 2) / 31250 - 1) >> 8;
  UBRR0L = ((F_CPU / 16 + 31250 / 2) / 31250 - 1);
  // Set frame format to 8 data bits, no parity, 1 stop bit
  UCSR0C |= (1 << UCSZ01) | (1 << UCSZ00);
  // enable rx
  UCSR0B |= _BV(RXEN0);
  // USART RX interrupt enable bit on
  UCSR0B |= _BV(RXCIE0);
  // Set up Timer 2 to do pulse width modulation on the speaker pin.
  // Use internal clock (datasheet p.160)
  ASSR &= ~(_BV(EXCLK) | _BV(AS2));
  // Set fast PWM mode (p.157)
  TCCR2A |= _BV(WGM21) | _BV(WGM20);
  TCCR2B &= ~_BV(WGM22);
  // Do non-inverting PWM on pin OC2A (p.155)
  // On the Arduino this is pin 11.
  TCCR2A = (TCCR2A | _BV(COM2A1)) & ~_BV(COM2A0);
  TCCR2A &= ~(_BV(COM2B1) | _BV(COM2B0));
  // No prescaler (p.158)
  TCCR2B = (TCCR2B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);
  // Set initial pulse width to the first sample.
  OCR2A = 128;
  // set up the ADC
  BENDoffset = analogRead(5);
  ADCSRA &= ~PS_128; // remove bits set by Arduino library
  // you can choose a prescaler from above. PS_16, PS_32, PS_64 or PS_128
  ADCSRA |= PS_128;
  ADMUX = 69;
  sbi(ADCSRA, ADSC);

  // MIDI channel DIP switches
  pinMode(DIP_SW1, INPUT_PULLUP);
  pinMode(DIP_SW2, INPUT_PULLUP);
  pinMode(DIP_SW3, INPUT_PULLUP);
  pinMode(DIP_SW4, INPUT_PULLUP);
  
  MIDI_CHANNEL = ReadDipSwitch();

  // Initialise MIDI
  MIDI.begin(MIDI_CHANNEL);
  MIDI.setThruFilterMode(midi::Thru::Off);

  // Initialise MIDI message handlers
  MIDI.setHandleNoteOff(midiNoteOffHandler);
  MIDI.setHandleNoteOn(midiNoteOnHandler);
}

/*

   MAIN LOOP

*/
void loop() {
 
  int8_t MUX = 3;
  while (1) {

    digitalWrite(10, TRIG);
    //--------------- ADC block -------------------------------------
    while (bit_is_set(ADCSRA, ADSC)) ; //Wait for ADC EOC
    if (MUX == 5) DETUNE = ((ADCL + (ADCH << 8)) >> 3);
    if (MUX == 5) MOD = ((ADCL + (ADCH << 8)) >> 2);
    if (MUX == 4) PHASERMIX = ((ADCL + (ADCH << 8)) >> 2);
    if (MUX == 3) ENVELOPE = ((ADCL + (ADCH << 8)) >> 5);
    if (MUX == 3) ATTACK = ATTrates[ENVELOPE];
    if (MUX == 3) RELEASE = RELrates[ENVELOPE];
    if (RELEASE == 255) GATED = 0;
    if (RELEASE != 255) GATED = 1;
    if (DETUNE != olddetune) {
      olddetune = DETUNE;
      for (uint8_t i = 0; i < 4; i++) {
        if (FREQ[i << 1]) {
          FREQ[(i << 1) | 1] = FREQ[i << 1] + (((FREQ[i << 1] / 50) >> 0) * DETUNE / 127);
        }
      }
    }
    MUX++;
    if (MUX > 5) MUX = 3;
    ADMUX = 64 | MUX; //Select MUX
    sbi(ADCSRA, ADSC); //start next conversation
    //--------------------------------------------------------------------
  }
}

/*

   MAIN INTERRUPT

*/
ISR(TIMER1_COMPA_vect) {

   // poll midi
   MIDI.read();

  //-------------------- 8 DCO block ------------------------------------------
  DCO = 0;
  for (uint8_t i = 0; i < 8; i++) {
    if (integrators[i]) integrators[i]--; //Decrement integrators
    DCOPH[i] += FREQ[i]; //Add freq to phaseacc's
    if (DCOPH[i] & 0x800000) { //Check for integrator reset
      DCOPH[i] &= 0x7FFFFF; //Trim NCO
      integrators[i] = 28; //Reset integrator
    }
    DCO += integrators[i];
  }
  writepointer++;
  delayline[writepointer] = DCO;
  DCO += (delayline[(writepointer - lfoval2) & 255] * PHASERMIX) >> 8;

  //------------------ VCA block ------------------------------------
#define M(MX, MX1, MX2) \
  asm volatile ( \
                 "clr r26 \n\t" \
                 "mulsu %B1, %A2 \n\t" \
                 "movw %A0, r0 \n\t" \
                 "mul %A1, %A2 \n\t" \
                 "add %A0, r1 \n\t" \
                 "adc %B0, r26 \n\t" \
                 "clr r1 \n\t" \
                 : \
                 "=&r" (MX) \
                 : \
                 "a" (MX1), \
                 "a" (MX2) \
                 : \
                 "r26" \
               )
  if ((ATTACK == 255) && (TRIG == 1)) VCA = 255;
  if (!(envcnt--)) {
    envcnt = 20;
    if (VCA < volume) VCA++;
    if (VCA > volume) VCA--;
  }
  M(ENV, (int16_t)DCO, VCA);
  OCR2A = ENV;

  //-------------- Calc Sample freq ---------------------------------
  OCR1A = 758 - lfoval;

}

/*

   LFO INTERRUPT

*/
ISR(TIMER0_COMPA_vect) {
   
  //------------------------------ LFO Block -----------------------
  lfocounter += LFO;
  lfoval = (pgm_read_byte_near( sinetable + lfocounter ) * MOD) >> 10; //LFO for pitch
  lfoval2 = pgm_read_byte_near( sinetable + (lfocounter2++) ); //LFO for the Phaser

  //--------------------- ENV block ---------------------------------
  if ((TRIG == 1) && (volume < 255)) {
    volume += ATTACK;
    if (volume > 255) volume = 255;
  }
  if ((TRIG == 0) && (volume > 0)) {
    volume -= RELEASE;
    if (volume < 0) volume = 0;
  }
}

/ ****************
  MIDI HANDLERS
***************** /
void midiNoteOnHandler(byte channel, byte note, byte velocity) {
  handleMIDINOTE(0x90, note, 127);
}

void midiNoteOffHandler(byte channel, byte note, byte velocity) {
  handleMIDINOTE(0x80, note, 0);
}

/*

   MISC METHODS

*/
//---------------- Get the base frequency for the MIDI note ---------------
uint32_t MIDI2FREQ(byte note) {
  uint8_t key = note % 12;
  if (note < 36) return (NOTES[key] >> (1 + (35 - note) / 12));
  if (note > 47) return (NOTES[key] << ((note - 36) / 12));
  return NOTES[key];
}

//---------------- Handle Notes---------------------------------------
void handleMIDINOTE(uint8_t message, uint8_t note, uint8_t vel) {
  uint8_t i;
  uint32_t freq;
  if ((!vel) && (message == 0x90)) message = 0x80;
  if (message == 0x80) {
    for (i = 0; i < 4; i++) {
      if (OSCNOTES[i] == note) {
        if (!GATED) {
          FREQ[i << 1] = 0;
          FREQ[(i << 1) | 1] = 0;
        }
        OSCNOTES[i] = 0;
      }
    }
    if (!(OSCNOTES[0] | OSCNOTES[1] | OSCNOTES[2] | OSCNOTES[3])) TRIG = 0;
    return;
  }
  if (message == 0x90) {
    if ((!TRIG) && (GATED)) {
      for (i = 0; i < 8; i++) {
        FREQ[i] = 0;
      }
    }
    i = 0;
    while (i < 4) {
      if (!OSCNOTES[i]) {
        freq = MIDI2FREQ(note);
        FREQ[i << 1] = freq;
        FREQ[(i << 1) | 1] = FREQ[i << 1] + (((FREQ[i << 1] / 50) >> 0) * DETUNE / 127);
        OSCNOTES[i] = note;
        if (!TRIG) {
          TRIG = 1;
        }
        return;
      }
      i++;
    }
  }
}

/*
 * Get MIDI channel from dipswitches
 */
byte ReadDipSwitch() {
  byte value = 0;
  if (digitalRead(DIP_SW4) == LOW) value += 1;
  if (digitalRead(DIP_SW3) == LOW) value += 2;
  if (digitalRead(DIP_SW2) == LOW) value += 4;
  if (digitalRead(DIP_SW1) == LOW) value += 8;
  return (value + 1);
}

```

---

<div class="post-metadata">

**Author:** ![RocketMermaid](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/rocketmermaid/32/26529_2.png) [@RocketMermaid](https://lookmumnocomputer.discourse.group/u/RocketMermaid)\
**Post date:** [July 19, 2023, 2:20am UTC](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81/516 "2023-07-19T02:20:38Z")

</div>

It’s super-simple, but I just built myself a handful of lowpass gates based on the VTL5C3 vactrol:

 ![LPGDiagram](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/d/2/d29147ee79b96ddd6e806f519bc501156ce2e031.png)

The top strip acts as ground for everything. You can also use different pots for slightly different responses - I built a quad LPG using two 20Ks, one 10K and one 50K.

[Previous page](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81.md?page=24)

[Next page](https://lookmumnocomputer.discourse.group/t/verified-stripboard-layouts/81.md?page=26)