├── Applications
└── ClockDivision_and_RhythmGeneration.md
├── Controller
├── Divide_Controller.c
└── README.md
├── Hardware
├── Control Board Schematic.png
├── FrontPanel
│ ├── SubHarmonics Front Panel.kicad_pcb
│ ├── SubHarmonics Front Panel.kicad_pro
│ └── SubHarmonics Front Panel.kicad_sch
├── Graphics
│ ├── Input Stage Switching Behaviour.md
│ ├── Modified Switching Labelled.png
│ ├── Modified Switching in Noise Labelled.png
│ ├── Noise 2.png
│ ├── Original Switching Labelled.png
│ ├── Original Switching in Same Noise Labelled.png
│ └── Original Switching in Same Noise Near Threshold Labelled.png
├── PCBs
│ ├── SubHarmonics Control Board v1 BoM.txt
│ ├── SubHarmonics Control Board v1.brd
│ ├── SubHarmonics Control Board v1.sch
│ ├── SubHarmonics Main Board BoM v2.txt
│ ├── SubHarmonics Main Board v2.brd
│ └── SubHarmonics Main Board v2.sch
├── README.md
└── SubHarmonics Main Board Schematic v2.png
├── LICENSE.txt
└── README.md
/Applications/ClockDivision_and_RhythmGeneration.md:
--------------------------------------------------------------------------------
1 | If you reduce the frequency of SubHarmonics' VCO or apply a clock signal to the 'Ext X In' from an LFO or similar source,
2 | you enable a range of opportunities in **Clock Division** and **Rhythm Generation**.
3 |
4 | ## SubHarmonics as a Clock Divider
5 |
6 | The two divider chains of SubHarmonics will offer direct division of the X clock by ratios of:
7 |
8 | 2, 4, 6, 8, 10, 12, 14 & 16 (for the A output)
9 |
10 | and
11 |
12 | 4, 6, 8, 10, 12, 14, 16, & 18 (for the B output)
13 |
14 | These divisions can be set either by the manual m & n divisor controls or by CV inputs.
15 |
16 | Many 'secondary' divisions can be established between A and B outputs.
17 |
18 | For example, with m=2 and n=6 the ratio between X and A is 1:2 and the ratio between X and B is 1:6,
19 | making the ratio between A and B 2:6 (1:3).
20 |
21 | Similarly, other odd integer ratios can be established via this 'secondary' approach, such that all integer ratios up
22 | to ten can be achieved:
23 |
24 |
25 | 
26 |
27 |
28 | Similarly, even integer divisions from 10 to 18 can be achieved directly.
29 |
30 | ## Building Rhythm using SubHarmonics
31 |
32 | Given the clock division described above, it is possible to take the divided clock signals and use them to trigger
33 | percussive sounds, making SubHarmonics a Rhythm Generator.
34 |
35 | The complexity of the rhythms generated is greatly increased if logic operations (AND, OR XOR, etc) are performed between
36 | the clock signals (X, A & B) to derive more interesting patterns.
37 |
38 | Remember that SubHarmonics has it's own pair of internal logic modulators, which combine the A and B signals (through OR
39 | and XOR functions). These are combined at the 'ModMix' output and can be selected by the 'Mix' control (or by CV).
40 | This was desiged for use when the ModMix output was interpreted as an 'analog' audio signal (rather than a Boolean switching
41 | signal). Accorindingly, there are a couple of issues for the present 'Rhythm Generator' application:
42 |
43 | 1) Signals from the 'ModMix' output are inverted, running from 0 to -3.75V. To use as conventional (positive true) logic
44 | signals, they must be inverted. I use a Voltage Processor to perform this inversion ('Maths' or any capable processor can
45 | do the job). You can just shift the level (rather than do an inversion) but this results in a different function - interesting
46 | as it will generate a different pattern and potentially useful if you don't have the resource to do the actual inversion.
47 |
48 | 2) There is no real meaning in the mixed signals for intermediate settings of the 'Mix' control in this context; the mix
49 | is only relevant to the output when used in 'analog' applications - so switching between the two modulators is best achieved
50 | with changes between extreme settings of the 'Mix' control (0 or 5V CV) to give either the XOR or the OR modulator.
51 |
52 | The consequence of changing the Mix control is illustrated in this example:
53 |
54 |
55 | 
56 |
57 |
58 | The 'scope traces show:
59 | * the X signal (top trace, Yellow)
60 | * the A subharmonic, m=8, (second trace, Cyan)
61 | * the B subharmonic, n=16, (third trace, Blue)
62 | * the Mix output, (bottom trace, Purple)
63 |
64 | The left-hand image shows the response with the OR modulator (Mix control fully clockwise or 5V CV Input) and the right-hand
65 | trace shows the response with the XOR modulator (Mix control fully counter clockwise or 0V CV input).
66 |
67 | Finally, AND **MOST IMPORTANTLY**, the two dividers are independant. This allows you to deliberately change the 'phase' between
68 | the SubHarmonics A & B. This introduces **additional variation in rhythm generation**.
69 |
70 | Variation is achieved by briefly changing the setting of one of the divisors (m or n), which introduces a relative delay
71 | (or advance, depending if you increase or decrease the divisor) relative to the other subharmonic, thereby changing the
72 | 'phase'.
73 |
74 | The process is not deterministic, but you will soon 'get the feel for it'.
75 |
76 | I prefer to adjust the largest divisor (i.e. max(m,n)) by one step for a couple of seconds and listen for the result before returning
77 | to the nominal value.
78 |
79 | There is a video, demonstrating these ideas with two percussion voices, [here](https://youtu.be/6WWO7RoppK4).
80 |
81 | The period, T0, of a pattern generated by mixing subharmonics m & n is given by:
82 |
83 | T0 = Tx.m.n/*gcd(m,n)*
84 |
85 | where Tx is the clock period and *gcd()* is the [greatest common divisor.](https://en.wikipedia.org/wiki/Greatest_common_divisor)
86 |
87 | Some examples are tabulated below:
88 |
89 |
90 | 
91 |
92 |
93 | You can easily set up a reasonably complex rhythm source, with triggers from A, B, logical operations on A and B (I like to
94 | use an external AND gate driven by A and B, occasionally with extra inputs - as there is no AND modulator internal to SubHarmonics)
95 | and, of course, ModMix.
96 |
97 | You establish a basic pattern by setting m & n and introduce variation by
98 | * changing the 'phase' and
99 | * switching between the internal modulators.
100 |
101 | ---
102 |
103 | **SubHarmonics** can be used to generate
104 | * melody, using its VCO,
105 | * bass, using its dividers,
106 | * harmony, using its modulators,
107 | * **and rhythm**, using the process described above.
108 |
--------------------------------------------------------------------------------
/Controller/Divide_Controller.c:
--------------------------------------------------------------------------------
1 | // Divide_Controller.c
2 | //
3 | // Software for the 'SubHarmonics' Harmonic Division VCO
4 | // m0xpd
5 | // 2023
6 | // https://github.com/m0xpd/SubHarmonics
7 | //
8 | //
9 | // PIC16F676 Configuration Bit Settings...
10 |
11 | #pragma config FOSC = INTRCIO // Oscillator Selection bits (INTOSC oscillator: I/O function on RA4/OSC2/CLKOUT pin, I/O function on RA5/OSC1/CLKIN)
12 | #pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT disabled)
13 | #pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT enabled)
14 | #pragma config MCLRE = ON // RA3/MCLR pin function select (RA3/MCLR pin function is MCLR)
15 | #pragma config BOREN = ON // Brown-out Detect Enable bit (BOD enabled)
16 | #pragma config CP = OFF // Code Protection bit (Program Memory code protection is disabled)
17 | #pragma config CPD = OFF // Data Code Protection bit (Data memory code protection is disabled)
18 |
19 |
20 | #include
21 | #define _XTAL_FREQ 4000000
22 |
23 | int Divide1 = 0;
24 | int Divide2 = 0;
25 | int voltage;
26 |
27 | void ADC_Init()
28 | {
29 | ADCON0 = 0x81; //ADC Module Turned ON and Clock is selected
30 | ADCON1 = 0b100; ;
31 | }
32 |
33 | unsigned int ADC_Read(unsigned char channel)
34 | {
35 | if(channel > 7) //If Invalid channel selected
36 | return 0; //Return 0
37 | ADCON0 &= 0x81; //Clear the Channel Selection Bits
38 | ADCON0 |= channel<<2; //Setting the required Bits
39 | __delay_ms(2); //time to charge hold capacitor
40 | GO_nDONE = 1; //Initializes A/D Conversion
41 | while(GO_nDONE); //Wait for A/D Conversion to complete
42 | return ((ADRESH<<8)+ADRESL); //Return Result
43 | }
44 |
45 | void setDiv1(){ // set Divider 1
46 | if(Divide1&1){
47 | RC5=1;
48 | }
49 | else{
50 | RC5=0;
51 | }
52 | if(Divide1&2){
53 | RC4=1;
54 | }
55 | else{
56 | RC4=0;
57 | }
58 | if(Divide1&4){
59 | RC3=1;
60 | }
61 | else{
62 | RC3=0;
63 | }
64 | }
65 |
66 | void setDiv2(){ // set Divider 2
67 | if(Divide2&1){
68 | RA5=1;
69 | }
70 | else{
71 | RA5=0;
72 | }
73 | if(Divide2&2){
74 | RA4=1;
75 | }
76 | else{
77 | RA4=0;
78 | }
79 | if(Divide2&4){
80 | RC0=1;
81 | }
82 | else{
83 | RC0=0;
84 | }
85 | }
86 | void main(){
87 | ANSEL=0X00; // all pins are digital
88 | TRISC=0X00;
89 | TRISA=0X00;
90 | // AN6 is analog input for Divide1 Potentiometer
91 | TRISC2 = 1; // on RC2, pin 8
92 | // AN5 is analog input for DIVIDE 2 Potentiometer
93 | TRISC1 = 1; // on RC1, pin 10
94 | ADC_Init();
95 |
96 |
97 | while(1){
98 | voltage=ADC_Read(0x6); // Just loop round doing this...
99 | Divide1=voltage/128;
100 | voltage=ADC_Read(0x5);
101 | Divide2=voltage/128;
102 | setDiv1();
103 | setDiv2();
104 | __delay_ms(5);
105 | }
106 |
107 | }
108 |
109 |
110 |
--------------------------------------------------------------------------------
/Controller/README.md:
--------------------------------------------------------------------------------
1 | # Controller Code for SubHarmonics
2 |
3 | Code for the PIC 16F676 microcontroller is found [here.](https://github.com/m0xpd/SubHarmonics/blob/main/Controller/Divide_Controller.c)
4 |
5 | It was developed in C in Microchip's [MPLAB IDE](https://www.microchip.com/en-us/tools-resources/develop/mplab-x-ide).
6 |
7 | The [code](https://github.com/m0xpd/SubHarmonics/blob/main/Controller/Divide_Controller.c) should be placed within an MPLAB project for the 16F676, built and programmed into the device using a suitable programmer.
8 |
9 | I programmed the first PIC using my [PICKit 3](https://www.microchip.com/en-us/development-tool/PG164130) and my old [k1el PIC Programming Adapter](https://hamcrafters2.com/PICPGM.html), but I designed an In-Circuit Serial Programming
10 | Interface into the SubHarmonics Main Board, so you can program directly on the module:
11 |
12 | 
13 |
14 |
15 | The PICKit3 supplies easily enough current to power the module; no special setting or modification needs to be made to the module during programming.
16 |
17 | I will try to post a complete MPLAB project (rather than just the C code) and a .hex file in this repository once I've figured out how to do it.
18 |
--------------------------------------------------------------------------------
/Hardware/Control Board Schematic.png:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/m0xpd/SubHarmonics/d5fe7d4088630697cd0fa463e93f25ff565f8afe/Hardware/Control Board Schematic.png
--------------------------------------------------------------------------------
/Hardware/FrontPanel/SubHarmonics Front Panel.kicad_pro:
--------------------------------------------------------------------------------
1 | {
2 | "board": {
3 | "design_settings": {
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13 | "dimension_precision": 4,
14 | "dimension_units": 3,
15 | "dimensions": {
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35 | "pads": {
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38 | "width": 1.524
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40 | "silk_line_width": 0.15,
41 | "silk_text_italic": false,
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43 | "silk_text_size_v": 1.0,
44 | "silk_text_thickness": 0.15,
45 | "silk_text_upright": false,
46 | "zones": {
47 | "45_degree_only": false,
48 | "min_clearance": 0.508
49 | }
50 | },
51 | "diff_pair_dimensions": [],
52 | "drc_exclusions": [],
53 | "meta": {
54 | "version": 2
55 | },
56 | "rule_severities": {
57 | "annular_width": "error",
58 | "clearance": "error",
59 | "copper_edge_clearance": "error",
60 | "courtyards_overlap": "error",
61 | "diff_pair_gap_out_of_range": "error",
62 | "diff_pair_uncoupled_length_too_long": "error",
63 | "drill_out_of_range": "error",
64 | "duplicate_footprints": "warning",
65 | "extra_footprint": "warning",
66 | "footprint_type_mismatch": "error",
67 | "hole_clearance": "error",
68 | "hole_near_hole": "error",
69 | "invalid_outline": "error",
70 | "item_on_disabled_layer": "error",
71 | "items_not_allowed": "error",
72 | "length_out_of_range": "error",
73 | "malformed_courtyard": "error",
74 | "microvia_drill_out_of_range": "error",
75 | "missing_courtyard": "ignore",
76 | "missing_footprint": "warning",
77 | "net_conflict": "warning",
78 | "npth_inside_courtyard": "ignore",
79 | "padstack": "error",
80 | "pth_inside_courtyard": "ignore",
81 | "shorting_items": "error",
82 | "silk_over_copper": "warning",
83 | "silk_overlap": "warning",
84 | "skew_out_of_range": "error",
85 | "through_hole_pad_without_hole": "error",
86 | "too_many_vias": "error",
87 | "track_dangling": "warning",
88 | "track_width": "error",
89 | "tracks_crossing": "error",
90 | "unconnected_items": "error",
91 | "unresolved_variable": "error",
92 | "via_dangling": "warning",
93 | "zone_has_empty_net": "error",
94 | "zones_intersect": "error"
95 | },
96 | "rules": {
97 | "allow_blind_buried_vias": false,
98 | "allow_microvias": false,
99 | "max_error": 0.005,
100 | "min_clearance": 0.0,
101 | "min_copper_edge_clearance": 0.0,
102 | "min_hole_clearance": 0.25,
103 | "min_hole_to_hole": 0.25,
104 | "min_microvia_diameter": 0.19999999999999998,
105 | "min_microvia_drill": 0.09999999999999999,
106 | "min_silk_clearance": 0.0,
107 | "min_through_hole_diameter": 0.3,
108 | "min_track_width": 0.19999999999999998,
109 | "min_via_annular_width": 0.049999999999999996,
110 | "min_via_diameter": 0.39999999999999997,
111 | "solder_mask_clearance": 0.0,
112 | "solder_mask_min_width": 0.0,
113 | "use_height_for_length_calcs": true
114 | },
115 | "track_widths": [],
116 | "via_dimensions": [],
117 | "zones_allow_external_fillets": false,
118 | "zones_use_no_outline": true
119 | },
120 | "layer_presets": []
121 | },
122 | "boards": [],
123 | "cvpcb": {
124 | "equivalence_files": []
125 | },
126 | "libraries": {
127 | "pinned_footprint_libs": [],
128 | "pinned_symbol_libs": []
129 | },
130 | "meta": {
131 | "filename": "SubHarmonics Front Panel.kicad_pro",
132 | "version": 1
133 | },
134 | "net_settings": {
135 | "classes": [
136 | {
137 | "bus_width": 12.0,
138 | "clearance": 0.2,
139 | "diff_pair_gap": 0.25,
140 | "diff_pair_via_gap": 0.25,
141 | "diff_pair_width": 0.2,
142 | "line_style": 0,
143 | "microvia_diameter": 0.3,
144 | "microvia_drill": 0.1,
145 | "name": "Default",
146 | "pcb_color": "rgba(0, 0, 0, 0.000)",
147 | "schematic_color": "rgba(0, 0, 0, 0.000)",
148 | "track_width": 0.25,
149 | "via_diameter": 0.8,
150 | "via_drill": 0.4,
151 | "wire_width": 6.0
152 | }
153 | ],
154 | "meta": {
155 | "version": 2
156 | },
157 | "net_colors": null
158 | },
159 | "pcbnew": {
160 | "last_paths": {
161 | "gencad": "",
162 | "idf": "",
163 | "netlist": "",
164 | "specctra_dsn": "",
165 | "step": "",
166 | "vrml": ""
167 | },
168 | "page_layout_descr_file": ""
169 | },
170 | "schematic": {
171 | "legacy_lib_dir": "",
172 | "legacy_lib_list": []
173 | },
174 | "sheets": [],
175 | "text_variables": {}
176 | }
177 |
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/Hardware/FrontPanel/SubHarmonics Front Panel.kicad_sch:
--------------------------------------------------------------------------------
1 | (kicad_sch (version 20211123) (generator eeschema)
2 | (paper "A4")
3 | (lib_symbols)
4 | (symbol_instances)
5 | )
6 |
--------------------------------------------------------------------------------
/Hardware/Graphics/Input Stage Switching Behaviour.md:
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1 | # Input Switching Behaviour
2 |
3 | The pulses applied to the SubHarmonics' divider chains are derived from either
4 | * the internal VCO or
5 | * the "Ext X In" input
6 |
7 | via the input stage formed of Q4 & Q5, Q6 and IC6C.
8 |
9 | These active elements amplify the input and form it into a pulse signal, which is saturated at levels of the +/- 12V
10 | power rails (at the collector of Q6) and subsequently half-wave rectified, inverted and attenuated (by D6 and IC6C)
11 | to pulses of approximately 5V.
12 |
13 | The Q4, Q5 stage is a stripped-down version of a conventional transistor [Schmitt Trigger.](https://en.wikipedia.org/wiki/Schmitt_trigger)
14 |
15 | In the present application, the input stage is required to have high sensitivity (a low value of 'HIGH THRESHOLD'),
16 | as the output of the VCO is rather small (~1.5 V peak). Accordingly, a low magnitude of the emitter resistor
17 | R19 = 10R was initially chosen in order to obtain a switching threshold of 0.85V.
18 |
19 | Unfortunately, this 10R resistor destroys almost all the hysteresis which is the defining property of a Schmitt Trigger.
20 |
21 | The images below show the switching behaviour of SubHarmonics with R19 at values of 10R and 470R.
22 |
23 |
24 | 
25 |
26 |
27 | 
28 |
29 |
30 | You can see that the 10 Ohm resistor results in switching of the 'X output' (Blue trace) at the same (0.85V) point on the upward
31 | and downward transistions of the External X input (Cyan trace). The switching point is shown by the 'scope's "A cursor", which
32 | superimoses a (white) horizontal line on the screen and records a numerical value at top left. The HIGH and LOW THRESHOLDS are
33 | equal and there is no hysteresis.
34 |
35 | The 470 Ohm resistor results in switching at 1.4V on upward transitions of the input (HIGH THRESHOLD = 1.4V, shown by the 'A cursor')
36 | whilst switching on the downward transition occurs at the lower input voltage of ~1.05V (LOW THRESHOLD = 1.05V, shown by the 'B cursor',
37 | which adds a dashed white horizontal line). There is now approximatey 0.35V of hysteresis.
38 |
39 | Although it is possible to further increase the emitter resistor magnitude in other applications (and thereby achieve greater hysteresis),
40 | this is won at the expense of still greater increases in the value of HIGH THRESHOLD. I have found that 470R is the largest
41 | value that can be used in SubHarmonics in order that the signal from the internal VCO is still detected.
42 |
43 | If we deliberately add 350mV (pk-pk) of noise:
44 |
45 |
46 | 
47 |
48 | to the external X input, the potential benefits of the Schmitt Trigger action become clear.
49 |
50 |
51 | The modified (R19=470R) circuit operates well in the presence of the noise,
52 |
53 |
54 | 
55 |
56 |
57 | with nice, clear, regular transitions of the (Blue) X output trace.
58 |
59 | However, the circuit in original configuration (R19 = 10R) suffers visible disruption of the (Blue) X output
60 | with the same noisy external X input
61 |
62 | 
63 |
64 |
65 | This can be made to LOOK more dramatic by reducing the input signal (and keeping the noise amplitude the same).
66 |
67 | 
68 |
69 |
70 | Note that it is not the peak 'signal' to noise ratio that is important; rather it is the THRESHOLD to noise ratio.
71 |
72 | What we did most significantly in the figure above was reduce the GRADIENT of the input signal around the
73 | threshold voltage, so we changed the effective timescale; the system spent more time around the decision point
74 | and there was more opportunity for the noise to cause false triggers, which showed up as visible lines on the 'scope.
75 |
76 | # Choosing a value for R19
77 |
78 | So, if you build a 'SubHarmonics' module you have a choice.
79 | * you could opt for the original R19 = 10R value, with the best possible input sensitivity (switching threshold = 0.85V),
80 | but NO Schmitt Trigger action, or
81 | * you could opt for the maximum R19 = 470R value, with a loss of input sensitivity (HIGH THSRESHOLD = 1.4V) and ~0.35V
82 | Schmitt Trigger 'hysteresis', or
83 | * you could opt for a mid-point compromise.
84 |
85 | I have built both versions (R19 = 10R, R19 = 470R). Both work well.
86 |
87 | I used the original (R19=10R) for six months and never noticed any problem with noise immunity on the 'Ext X In' input
88 | which made me wish there was Schmitt Trigger action. However, we are used to having high amplitude, noise-free signals
89 | avaialble from our oscillators, so that's hardly surprising.
90 |
91 | On the other hand, now I've enabled the Schmitt Trigger functionality, the same high amplitude oscillator and clock
92 | signals can still trigger the SubHarmonics module at the 'Ext X In' input but I get the "extra insurance" of 0.35V of
93 | noise immunity at no additional expense (a 470R resistor is no more expensive than a 10R resistor - or even a wire link!).
94 |
95 | So - all things considered - I guess I prefer the revised version with R19 = 470R.
96 |
97 | You must make your own choice.
98 |
99 | # Acknowledgement
100 |
101 | All this interest in the magnitude of R19 and the reinstatement of Schmitt Trigger action was prompted by a question raised
102 | by Yves Chartier, and subsequent discussion. I am grateful for Yves' valuable contribution and support.
103 |
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/Hardware/PCBs/SubHarmonics Control Board v1 BoM.txt:
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1 | Partlist exported from /Users/pauldarlington/Documents/EAGLE/projects/Harmonic Division Oscillator/SubHarmonics Control Board v1.sch at 04/05/2023 07:58
2 |
3 | Part Value Device Package Description POPULARITY SPICEPREFIX
4 | C11 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
5 | C12 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
6 | C13 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
7 | D9 1N5817-T 1N5817-T DO41-7.6 1.0A SCHOTTKY BARRIER RECTIFIER 0
8 | D10 1N5817-T 1N5817-T DO41-7.6 1.0A SCHOTTKY BARRIER RECTIFIER 0
9 | D11 1N5817-T 1N5817-T DO41-7.6 1.0A SCHOTTKY BARRIER RECTIFIER 0
10 | D12 1N5817-T 1N5817-T DO41-7.6 1.0A SCHOTTKY BARRIER RECTIFIER 0
11 | IC11 4051N 4051N DIL16 8-channel ANALOG MULTIPLEXER 15
12 | IC12 4051N 4051N DIL16 8-channel ANALOG MULTIPLEXER 15
13 | JP4 PINHD-1X20 1X20 PIN HEADER 6
14 | JP5 PINHD-1X20 1X20 PIN HEADER 6
15 | LED1 LED3MM LED3MM LED
16 | LED2 LED3MM LED3MM LED
17 | LED3 LED3MM LED3MM LED
18 | LED4 LED3MM LED3MM LED
19 | LED5 LED3MM LED3MM LED
20 | LED6 LED3MM LED3MM LED
21 | LED7 LED3MM LED3MM LED
22 | LED8 LED3MM LED3MM LED
23 | LED9 LED3MM LED3MM LED
24 | LED10 LED3MM LED3MM LED
25 | LED11 LED3MM LED3MM LED
26 | LED12 LED3MM LED3MM LED
27 | LED13 LED3MM LED3MM LED
28 | LED14 LED3MM LED3MM LED
29 | LED15 LED3MM LED3MM LED
30 | LED16 LED3MM LED3MM LED
31 | R30 1k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
32 | R31 220k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
33 | R32 10k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
34 | R33 1k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
35 | R34 220k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
36 | R35 10k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
37 | R36 1k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
38 | R37 220k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
39 | R38 470 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
40 | R39 470 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
41 | R40 470 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
42 | R41 470 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
43 | R42 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
44 | R43 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
45 | R44 33k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
46 | R45 1M R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
47 | R46 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
48 | R47 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
49 | R48 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
50 | R49 2k2 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
51 | R50 2k2 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
52 | SK1 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
53 | SK2 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
54 | SK3 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
55 | SK4 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
56 | SK5 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
57 | SK6 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
58 | SK7 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
59 | SK8 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
60 | SK9 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
61 | SK10 THONKICONN_JACK THONKICONN_JACK WQP-PJ301M-12_JACK
62 | VAR1 10k VARISTOR C025-024X044 NTC Varistor
63 | VAR2 10k VARISTOR C025-024X044 NTC Varistor
64 | VAR3 10k VARISTOR C025-024X044 NTC Varistor
65 | VAR4 10k VARISTOR C025-024X044 NTC Varistor
66 | VR1 100k 9MM_SNAP-IN_POT_ 9MM_SNAP-IN_POT 9mm vertical snap-in pot, Alpha / Panasonic style
67 | VR2 100k 9MM_SNAP-IN_POT_ 9MM_SNAP-IN_POT 9mm vertical snap-in pot, Alpha / Panasonic style
68 | VR3 1M 9MM_SNAP-IN_POT_ 9MM_SNAP-IN_POT 9mm vertical snap-in pot, Alpha / Panasonic style
69 | VR4 100k 9MM_SNAP-IN_POT_ 9MM_SNAP-IN_POT 9mm vertical snap-in pot, Alpha / Panasonic style
70 | VR5 100k 9MM_SNAP-IN_POT_ 9MM_SNAP-IN_POT 9mm vertical snap-in pot, Alpha / Panasonic style
71 | VR6 100k 9MM_SNAP-IN_POT_ 9MM_SNAP-IN_POT 9mm vertical snap-in pot, Alpha / Panasonic style
72 |
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/Hardware/PCBs/SubHarmonics Main Board BoM v2.txt:
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1 | Partlist exported from /Users/pauldarlington/Documents/EAGLE/projects/Harmonic Division Oscillator/SubHarmonics Main Board v2.sch at 22/10/2023 07:06
2 |
3 | Part Value Device Package Description MF MPN OC_FARNELL OC_NEWARK POPULARITY SPICEPREFIX
4 | C1 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
5 | C2 1u CPOL-EUE2.5-5 E2,5-5 POLARIZED CAPACITOR, European symbol 16 C
6 | C3 10u CPOL-EUE2.5-5 E2,5-5 POLARIZED CAPACITOR, European symbol 16 C
7 | C4 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
8 | C5 22u CPOL-EUE2.5-5 E2,5-5 POLARIZED CAPACITOR, European symbol 16 C
9 | C6 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
10 | C7 22u CPOL-EUE2.5-5 E2,5-5 POLARIZED CAPACITOR, European symbol 16 C
11 | C8 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
12 | C9 0.1u C-EU050-025X075 C050-025X075 CAPACITOR, European symbol 29 C
13 | C10 2n2 C-EU050-030X075 C050-030X075 CAPACITOR, European symbol 9 C
14 | C11 1u CPOL-EUE2.5-5 E2,5-5 POLARIZED CAPACITOR, European symbol 16 C
15 | D1 1N5817 SCHOTTKY-DIODEDO35-7 DO35-7 Schottky Diode 3
16 | D2 1N5817 SCHOTTKY-DIODEDO35-7 DO35-7 Schottky Diode 3
17 | D3 1N4148DO35-7 1N4148DO35-7 DO35-7 DIODE 58
18 | D4 1N4148DO35-7 1N4148DO35-7 DO35-7 DIODE 58
19 | D5 1N4148DO35-7 1N4148DO35-7 DO35-7 DIODE 58
20 | D6 1N4148DO35-7 1N4148DO35-7 DO35-7 DIODE 58
21 | D7 1N4148DO35-7 1N4148DO35-7 DO35-7 DIODE 58
22 | D8 1N4148DO35-7 1N4148DO35-7 DO35-7 DIODE 58
23 | IC1 40106N 40106N DIL14 Hex SCHMITT TRIGGER 4
24 | IC2 4051N 4051N DIL16 8-channel ANALOG MULTIPLEXER 15
25 | IC3 4051N 4051N DIL16 8-channel ANALOG MULTIPLEXER 15
26 | IC4 PIC16F676P PIC16F676P DIL14 14-Pin, Flash-Based 8-Bit CMOS Microcontroller MICROCHIP PIC16F676-I/P 9760512 54K2829 0
27 | IC5 LM324N LM324N DIL14 OP AMP 9
28 | IC6 LM324N LM324N DIL14 OP AMP 9
29 | IC7 4017N 4017N DIL16 COUNTER/DIVIDER 2
30 | IC8 4017N 4017N DIL16 COUNTER/DIVIDER 2
31 | IC9 4013N 4013N DIL14 Dual D FLIP FLOP, set/reset 4
32 | IC10 4001N 4001N DIL14 Quad 2-input NOR 1
33 | IC11 LM13700N LM13700N DIL16 Dual OTA with buffers
34 | IC12 78LXX 78LXX VOLTAGE REGULATOR 6
35 | JP1 PINHD-1X6 1X06 PIN HEADER 79
36 | JP2 PINHD-1X20 1X20 PIN HEADER 6
37 | JP3 PINHD-1X20 1X20 PIN HEADER 6
38 | Q1 2N3906 2N3906 TO92 PNP Transistor 11
39 | Q2 BC556A BC556A TO92-EBC PNP Transistror 0
40 | Q3 BC546A BC546A TO92-EBC NPN Transistor 0
41 | Q4 BC546A BC546A TO92-EBC NPN Transistor 0
42 | Q5 BC546A BC546A TO92-EBC NPN Transistor 0
43 | Q6 BC556A BC556 TO92-EBC PNP Transistror 2
44 | R1 10 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
45 | R2 10 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
46 | R3 10k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
47 | R4 270k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
48 | R5 10k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
49 | R6 1k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
50 | R7 6k8 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
51 | R8 220k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
52 | R9 220k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
53 | R10 1k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
54 | R11 1k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
55 | R12 47k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
56 | R13 1k5 R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
57 | R14 1M R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
58 | R15 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
59 | R16 1M R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
60 | R17 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
61 | R18 22k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
62 | R19 See Text R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
63 | R20 22k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
64 | R21 33k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
65 | R22 10k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
66 | R23 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
67 | R24 47k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
68 | R25 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
69 | R26 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
70 | R27 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
71 | R28 100k R-EU_0204/7 0204/7 RESISTOR, European symbol 79 R
72 | TR1 100k BOURNS_3362P_TRIMMERP BOURNS_3362P_TRIMMER 3362 Series
73 | TR2 1k TRIM_EU-B64Y B64Y POTENTIOMETER 0
74 | X2 2510- 2510- PAK100/2500-10 3M (TM) Pak 100 4-Wall Header 3M 2510-6002UB 9838244 46F4725 0
75 |
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/Hardware/README.md:
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1 | # Hardware
2 | This folder contains hardware descriptions of the 'SubHarmonics' module.
3 |
4 | The information is presented as EAGLE 'sch' and 'brd' files for the two PCBs (in the [PCBs folder](https://github.com/m0xpd/SubHarmonics/tree/main/Hardware/PCBs) ) and as a small Kicad project for the front panel (in
5 | the FrontPanel folder).
6 |
7 | SubHarmonics is implemented in two modules, each of which has its own PCB. There is a Main Board, hosting the majority of the electronics and
8 | a Control Board, which contains all the front panel components including the division indicator LEDs and associated decoders.
9 |
10 | ## Main Board Description
11 |
12 | The Main Board schematic is available [here](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/SubHarmonics%20Main%20Board%20Schematic%20v2.png) (or by clicking on the graphic below)
13 |
14 |
15 |
16 | 
17 |
18 |
19 | The VCO was inspired by the ['Shapes VCO' design by Moritz Klein](https://www.youtube.com/watch?v=QBatvo8bCa4), subsequently used in his VCO for the [Erica Synths Edu DIY VCO](https://www.ericasynths.lv/shop/diy-kits-1/edu-diy-vco/). Since developing 'SubHarmonics', I have learned that the core of the 40106 VCO was not a Klein original, but had been proposed earlier by Mark Shaner (a.k.a. "Synthmonger"), who published the idea [here](https://electro-music.com/forum/topic-28799.html) back in 2008.
20 |
21 | The output of this 'Shaner' 40106 VCO - or the input from an external 'X' source - is applied to the 'Divider_In' input of the SubHarmonic Dividers, the input stages of which produce a 0 : 5V pulse at node 'X' on the schematic. There is a detailed description of the derivation of this pulse signal, including
22 | discussion of options to set shared emitter resistor R19 to either maximise input sensitivity or enable a degree of noise immunity, [here.](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/Graphics/Input%20Stage%20Switching%20Behaviour.md)
23 |
24 | The system was designed around 'available materials' I found lying around my bench - in this case, mainly CD4000-series CMOS logic devices.
25 |
26 | The divisions in each of the two channels are achieved by a CD4015 (Decade counter) and a CD4051 (Analog Mux/Demux) in conventional
27 | configuration. The divisor is set by a PIC microcontroller, which reads a potentiometer or a CV input signal and decodes the voltage (0-5V) into
28 | one-of-8 settings for the dividers.
29 |
30 | A further divide-by-2 stage, implemented in a CD4013 (D-type SR flip-flop) applied to the outputs of the dividers adds another octave of division
31 | (necessary to implement the m=2 setting on the A channel).
32 |
33 | The outputs of the dividers, A and B (and their complements, not_A and not_B) are fed to two modulators, implemented in a quad NOR package (CD4001).
34 |
35 | The results of the OR and XOR operations are mixed in a voltage-controlled crossfader, implemented in half an LM13700.
36 |
37 | The [schematic](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/SubHarmonics%20Main%20Board%20Schematic%20v2.png) and [BoM](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/PCBs/SubHarmonics%20Main%20Board%20BoM%20v2.txt) show LM324 quad op-amps. These work fine in this application, but you can substitute the ubiquitous TL074 if you prefer.
38 |
39 | The Main Board includes an In-Circuit Serial Programming (ICSP) interface (JP1) to facilitate programming the PIC.
40 |
41 | There is a [.sch](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/PCBs/SubHarmonics%20Main%20Board%20v2.sch) file, a [.brd](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/PCBs/SubHarmonics%20Main%20Board%20v2.brd) file and a [BoM](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/PCBs/SubHarmonics%20Main%20Board%20BoM%20v2.txt) for the Main Board in EAGLE format in the [PCBs folder](https://github.com/m0xpd/SubHarmonics/tree/main/Hardware/PCBs).
42 |
43 | ## Control Board Description
44 |
45 | The Control Board schematic is available [here](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/Control%20Board%20Schematic.png) (or by clicking on the graphic below)
46 |
47 |
48 | 
49 |
50 |
51 | In addition to controls, inputs and outputs, the Control Board hosts the division indicator LEDs and decoders to control these (which again use
52 | CD4051 analog demuxers).
53 |
54 | As well as to CV inputs for Pitch and FM, there are CV inputs for the divisors m and n and for the modulation mix. These last three are designed
55 | to operate over a range of 0 to 5V, but are protected such that voltages outside these limits will cause no damage.
56 |
57 | A 0V input on the modulation mix CV input gives the XOR modulation and a 5V input gives the OR modulation (which is spectrally richer, as it includes the
58 | harmonics of A and B as well as the sum and difference harmonics). An intermediate control voltage gives a mix of both modulation types.
59 |
60 | There is a [.sch](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/PCBs/SubHarmonics%20Control%20Board%20v1.sch) file, a [.brd](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/PCBs/SubHarmonics%20Control%20Board%20v1.brd) file and a [BoM](https://github.com/m0xpd/SubHarmonics/blob/main/Hardware/PCBs/SubHarmonics%20Control%20Board%20v1%20BoM.txt) for the Control Board in EAGLE format in the [PCBs folder.](https://github.com/m0xpd/SubHarmonics/tree/main/Hardware/PCBs)
61 |
62 | The Main and Control boards are joined by two 20-way 0.1 inch pitch headers. These have been specified with electrical redundancy (several pins are
63 | unused) to provide mechanical stability and security in assembling the module.
64 |
65 |
66 | The completed PCBs are seen in the photo below, which shows the Main Board from both sides and the Control Board from the 'top' side (the front panel
67 | components all are mounted on the 'bottom' side).
68 |
69 |
70 | 
71 |
72 |
73 |
74 | ## Front Panel
75 |
76 |
77 | 
78 |
79 |
80 |
81 | A simple Kicad project defining a Front Panel for the module is available in the [FrontPanel folder.](https://github.com/m0xpd/SubHarmonics/tree/main/Hardware/FrontPanel)
82 |
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/Hardware/SubHarmonics Main Board Schematic v2.png:
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https://raw.githubusercontent.com/m0xpd/SubHarmonics/d5fe7d4088630697cd0fa463e93f25ff565f8afe/Hardware/SubHarmonics Main Board Schematic v2.png
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/README.md:
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1 | # SubHarmonics
2 |
3 |
4 | 'SubHarmonics' is a Eurorack module which generates two squarewaves ('A' and 'B') which are sub-harmonics of another signal, 'X'.
5 |
6 |
7 | 
8 |
9 |
10 |
11 | The signal X is either
12 | i) generated by the module's internal Voltage Controlled Oscillator
13 | or
14 | ii) is derived from an external signal applied to the module's 'Ext X In' input.
15 |
16 | The sub-harmonics are generated by hardware dividers, which divide the frequency of X by integer divisors (m, n) of 2, 4, 6, 8, 10, 12, 14, 16 or 18,
17 | giving the unit a range of a little over four octaves (18 ≈ 2 4.17 ).
18 |
19 | These divisors (m := f x / f A , n := f x / f B ) are voltage controlled - they can be set by potentiometers or by control voltages applied from external sources.
20 |
21 | It is seen that the signals A and B are themselves related in frequency by 'the ratio of two small integers' (m/n). So, in addition to each being
22 | sub-harmonics of X, the ratio between A and B often falls at a musically useful interval;
23 |
24 | 'SubHarmonics' generates harmony as well as bass.
25 |
26 |
27 |
28 | Other applications of 'SubHarmonics' in Clock Division and Rhythm Generation are described [here.](https://github.com/m0xpd/SubHarmonics/blob/main/Applications/ClockDivision_and_RhythmGeneration.md)
29 |
30 |
31 |
32 | ### Internal Modulators
33 |
34 | SubHarmonics includes a pair of internal modulators, which combine the A and B signals together (through an OR and an Exclusive OR operation) to
35 | exploit and develop the harmonic relationship between A and B into a richer sound. The OR modulation is equivalent (for these signals A, B) to simple
36 | amplitude modulation, as performed by (e.g.) an AND gate, whilst the Exclusive OR modulation implements the balanced modulation of A with B (as in a
37 | 'ring modulator'). I described the equivalence of OR and AND gates as modulators for the special class of 'antipalindromic' inputs (such as the present
38 | A and B signals) at tedious length [here.](http://m0xpd.blogspot.com/2023/03/logic-gates-and-modulation-curiosity.html)
39 |
40 | The two different modulation results are combined in a voltage-controlled crossfader circuit (controlled by a potentiometer or an external CV input)
41 | to give a single output which offers a choice OR A MIX of the modulation types at the 'Mod Mix' output.
42 |
43 | An introductory video, demonstrating SubHarmonics' features, is available [here](https://youtu.be/j_IT1Ucp6_4)
44 |
45 | ### Setup
46 |
47 | There are two presets that need adjustment on completion of the module to setup for use. Both are located on the topside of the Main Board.
48 |
49 | TR2 (a multi-turn 1k preset) controls the 1V/Octave tracking. It should be set by connecting the module to a reliable source of pitch CV signals and monitoring the outputs. I use octave outputs from a BeatStep Pro (you can use a keyboard with CV pitch outputs or simply a known voltage source) and listen to the pitch change. I find it easy to tune octaves by ear but, if you are uncertain, use a tuner or frequency counter.
50 |
51 | TR1 (a single turn 100k preset) controls the balance of the modulation mix crossfader. To set it properly requires access to an oscilloscope to see the 'Mod Mix' output waveform. If you have no access to a 'scope, set TR1 to about 60kΩ.
52 |
53 | If you do have a 'scope, set the divisors to m=2, n=6 (using the front panel controls) and the frequency to an arbitrary value (around 300Hz). View the 'A' and 'Mod Mix' outputs on the 'scope. Adjust TR1 until you see these waveforms when you put the Mix control at extreme ends of its travel (or, equivalently, apply 0V or 5V CV signals to the Mix input):
54 |
55 |
56 | 
57 |
58 |
59 | (the yellow trace is the 'A' output, which stays the same in this setup process and is included only as a 'reference', the blue trace is the 'Mod Mix' output, which will change when you adjust TR1)
60 |
61 | [If you do not see this waveform on the ModMix output with these settings, it may be due to the phase relationship between the dividers - if this is the case, change the value of 'n' using the potentiometer all the way up to 18 and back to 6 and see if the phase is re-aligned. This is perfectly normal and is not a fault - there is another 'mode' of the system in the m=2, n=6 configuration to that illustrated above.]
62 |
63 | Note that the 'Mod Mix' output is inverted (it runs 0 to approx -4V); there wasn't a spare op-amp stage to restore polarity after the crossfader.
64 | This doesn't matter in ordinary applications; the ear is insensitive to the inversion and it will sound the same! There are, however, some implications of this inversion which are important to the 'time-domain' applications discussed [here.](https://github.com/m0xpd/SubHarmonics/blob/main/Applications/ClockDivision_and_RhythmGeneration.md)
65 |
66 |
67 |
68 | ### Miscellaneous Details
69 |
70 | The sub-harmonic generation and all signal processing is performed in hardware.
71 |
72 | A small (PIC) microcontroller is used to read the potentiometers and CV inputs and set the dividers.
73 |
74 | Details of the two PCBs and front panel are provided in the [Hardware](https://github.com/m0xpd/SubHarmonics/tree/main/Hardware) folder. Code for
75 | the 16F676 PIC is presented in the [Controller](https://github.com/m0xpd/SubHarmonics/tree/main/Controller) folder.
76 |
77 | SubHarmonics is:
78 | 12HP wide,
79 | requires 38mm behind the front panel (with the power header fitted) and
80 | draws 13.5mA from the 12V rail and 5mA from the -12V rail.
81 |
82 | The design is published under a Creative Commons CC BY-SA 4.0 [License](https://github.com/m0xpd/SubHarmonics/blob/main/LICENSE.txt).
83 |
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