Tuned Harmonic Circuits

Pure Harmony GPL

 


2/1, the octave, is the most harmonically consonant musical interval.

3/2, the perfect fifth, is the second most harmonically consonant musical interval.

4/3, the perfect fourth, is the third most harmonically consonant musical interval.

This is the basis for Pure Harmony.

 

Equal Temperament Tuning is equally out of tune in all 12 keys, it is a compromise tuning.

Just Intonation/Pythagorean Tuning is in tune, in 1 of 12 keys. Traditionally, and as is still the case for all non-electronically pitched instruments, 12 different instruments are needed and a mid-song key change would require quickly switching guitars or jumping to another piano. Taking 12 instruments with me to anywhere I wanted to practice or perform material in any 2 or more key signatures is simply not practical.

Nowadays, with advancements in electronics, software and MIDI, it is entirely possible to carry just one instrument with me, and have the choice at the push of a button or pedal to choose between 12TET Equal Temperament, Just Intonation tuning in any key, Pythagorean Tuning in any key, as well as customisable microtonal tuning systems that can be dialled in and saved.

When tuned electronically, pure harmonic tuning systems allow the opportunity to play perfectly in tune, in all 12 keys, simply pressing a button or footswitch at the moment that there is a key change/modulation in the song.


The Arduino platform has been chosen to develop software-based pure harmonic top octave generators. Arduino Uno R3 or ATMega328P with Arduino R3 bootloader is the hardware that we are going to use for our examples.

A number of electronic musical instruments can be built from this, electronic organs and keyboards that use top octave generator chips can be modified to play pure harmonic tunings by swapping them out for this circuit.

Stay tuned, code and schematics will follow…

 

Choice Components

Here are some of the choice components that will feature in many of our future projects.

This list includes some legendary classics and some of our all-time favourites.

NE555 – Timer
http://www.ti.com/lit/ds/symlink/ne555.pdf

ICM7555 – CMOS RC Timer
https://www.intersil.com/content/dam/Intersil/documents/icm7/icm7555-56.pdf

PT2399 – Echo Processor IC
http://sound.westhost.com/pt2399.pdf

LTC-1799 – 1kHz to 33Mhz Precision Oscillator
http://cds.linear.com/docs/en/datasheet/1799fc.pdf

DS1307 – 64 x 8, Serial, I2C Real-Time Clock
http://datasheets.maximintegrated.com/en/ds/DS1307.pdf

M083B1 – Tone Generators / Top Octave Generators
http://www.milton.arachsys.com/nj71/pdf/m082.pdf

MK50240 – Top Octave Frequency Generator
http://synthdiy.com/files/2001/mk50240.pdf

ICL7226BIPL – 8-Digit Multi-Function Frequency Counter/Timer
http://www.intersil.com/content/dam/Intersil/documents/icm7/icm7226a-b.pdf

LM567CN – Tone Decoder
http://www.ti.com.cn/cn/lit/ds/symlink/lm567.pdf

ICL8038CCPD – Precision Waveform Generator/VCO
http://www.intersil.com/content/dam/Intersil/documents/icl8/icl8038.pdf

ISD4003 – Single-Chip Voice Record/Playback Devices
http://melabs.com/downloads/ISD4003.pdf

MSP430G2553 – Microcontroller
http://www.ti.com/lit/ds/symlink/msp430g2553.pdf

MSP430G2231 – Microcontroller
http://www.ti.com/product/MSP430G2231
http://www.ti.com/lit/ds/slas694j/slas694j.pdf

MSP430G2211 – Microcontroller
http://www.ti.com/lit/ds/symlink/msp430g2201.pdf

PIC16C63A – Microcontroller
http://ww1.microchip.com/downloads/en/DeviceDoc/30605D.pdf

PIC16F616 – Microcontroller
http://ww1.microchip.com/downloads/en/DeviceDoc/41288F.pdf

PIC16C924 – Microcontroller
http://www.alliedelec.com/m/d/a0b1fb1792da2d11650006dd6be1072f.pdf

AT89C2051-24PU – Microcontroller
http://www.atmel.com/images/doc0368.pdf

PCD8544/5110LCD – 48×84 Pixels Matrix LCD Controller/Driver
https://www.sparkfun.com/datasheets/LCD/Monochrome/Nokia5110.pdf

SN74HC595 – 8-Bit Shift Registers
http://www.ti.com/lit/ds/symlink/sn74hc595.pdf

SN76489AN – Digital Complex Sound Generator
http://www-uxsup.csx.cam.ac.uk/~bjh21/BBCdata/SN76489.pdf

SN74LS292N – Programmable Frequency Dividers and Digital Timers
http://www.ti.com.cn/cn/lit/ds/symlink/sn74ls294.pdf

SN74LS48 – BCD to 7-Segment Display
http://www.ti.com/lit/ds/symlink/sn5447a.pdf

SN74116N – Dual 4-Bit Latches with Clear
http://www.unicornelectronics.com/ftp/Data%20Sheets/74116.pdf

SN74LS151N – Data Selectors/Multiplexers
http://www.ti.com.cn/cn/lit/ds/symlink/sn54150.pdf

74LS86N – Quad 2-Input Exclusive OR Gate
http://www.applelogic.org/files/74LS86.pdf

DM74LS21N – Dual 4-Input AND Gates
http://ecee.colorado.edu/~mcclurel/fnm74ls21.pdf

DM74LS20N – Dual 4-Input NAND Gates
http://www.ti.com/lit/ds/symlink/dm54ls20.pdf

DM74LS54N – 4 Wide, 2-Input AND-OR-INVERT Gate
http://pdf.datasheetcatalog.com/datasheets2/53/53555_1.pdf

SN74LS157N – Quad 2-1 Data Selectors/Multiplexers
http://www.ti.com/lit/ds/symlink/sn54ls157.pdf

SN74LS160AN – BCD Decade/4-Bit Binary Counters
http://www.onsemi.com/pub_link/Collateral/SN74LS160A-D.PDF

SN74LS156N – Dual 2-4 Line Decoders/Demultiplexers
http://www.ti.com/lit/ds/symlink/sn74ls155a.pdf

SN74LS174N – Hex D-Type Flip-Flops with Clear (Single Rail Outputs)
http://www.ti.com/lit/ds/symlink/sn74s175.pdf

SN74LS175N – Quad D-Type Flip-Flops with Clear (Double Rail Outputs)
http://www.ti.com/lit/ds/symlink/sn74s175.pdf

SN7490AN – Decade Counters
http://www.ti.com/lit/ds/symlink/sn74ls90.pdf

SN7495AN – 4-Bit Parallel-Access Shift Registers
http://www.ti.com/lit/ds/symlink/sn7495a.pdf

SN74LS132N – Quad 2-Input Positive-NAND Schmitt Triggers
http://www.ti.com.cn/cn/lit/ds/symlink/sn74ls132.pdf

SN74LS163AN – 4-Bit Binary Counters (A/AN?)
http://www.ti.com.cn/cn/lit/ds/symlink/sn74ls161a.pdf

SN74LS09N – Quad 2-Input Positive-AND Gates with Open-Collector Outputs
http://www.ti.com/lit/ds/symlink/sn74ls09.pdf

SN7400N/SN74LS00N – Quad 2-Input Positive-NAND Gates
http://www.ti.com.cn/cn/lit/ds/symlink/sn74ls00.pdf

SN7416N – Hex Inverter Buffers/Drivers
http://www.ti.com.cn/cn/lit/ds/symlink/sn7406.pdf

SN74123N/SN74LS123N – Retriggerable Monostable Multivibrators
http://www.ti.com/lit/ds/symlink/sn74ls123.pdf

SN74LS136N – Quad 2-Input Exclusive-OR Gates
http://www.ti.com/lit/ds/sdls048/sdls048.pdf

SN74LS139N – Dual 1-of-4 Decoder/Demultiplexer
https://www.seattleu.edu/media/college-of-science-and-engineering/files/departments/electricalandcomputerengineering/74ls13969bd.pdf

SN74LS164N – 8-Bit Parallel-Out Serial Shift Registers
http://www.ti.com/lit/ds/symlink/sn74ls164.pdf

SN74LS165AN – Parallel-Load 8-Bit Shift Registers
http://www.ti.com/lit/ds/symlink/sn74ls165a.pdf

SN74HC240N – Octal Buffers and Line Drivers with 3-State Outputs
http://www.ti.com/lit/ds/symlink/sn54hc240.pdf

SN74LS14N – Hex Schmitt Trigger Inverters
http://www.ti.com/lit/ds/symlink/sn74ls14.pdf

CD40106B – Hex Schmitt Trigger Inverters
http://www.ti.com/lit/ds/symlink/cd40106b-mil.pdf

CD4040B – 12-Stage Binary Counter/Divider
http://www.ti.com.cn/cn/lit/ds/symlink/cd4040b.pdf

CD4017BE – Decade Counter
http://www.ti.com/lit/ds/symlink/cd4022b.pdf

CD4051BE – 8-Channel Analogue Multiplexer
http://www.ti.com.cn/cn/lit/ds/symlink/cd4051b.pdf

CD4046B – PLL Phase-Locked Loop
http://www.ti.com/lit/ds/symlink/cd4046b.pdf

CD4049UB – Hex Buffer/Converters
http://www.ti.com/lit/ds/symlink/cd4049ub-mil.pdf

CD4518B – Dual Up-Counters
http://www.ti.com/lit/ds/symlink/cd4518b.pdf

CD4093B – Quad 2-Input NAND Schmitt Triggers
http://www.ti.com.cn/cn/lit/ds/symlink/cd4093b.pdf

CD4510B – Presettable Up/Down Counters
http://www.ti.com.cn/cn/lit/ds/symlink/cd4516b.pdf

CD4029B – Presettable Up/Down Counter
http://www.ti.com/lit/ds/symlink/cd4029b.pdf

CD4521 – 24-Stage Frequency Divider
http://www.ti.com/lit/ds/symlink/cd4521b.pdf

CD4021BE – 8-Stage Static Shift Registers
http://www.ti.com/lit/ds/symlink/cd4021b.pdf

CD4082B – AND Gates
http://www.ti.com/lit/ds/symlink/cd4073b.pdf

CD4060B – 14-Stage Ripple-Carry Binary Counter/Divider and Oscillator
http://www.ti.com/lit/ds/symlink/cd4060b.pdf

CD4511 – BCD-to-7-Segment Latch Decoder Drivers
http://www.ti.com/lit/ds/symlink/cd4511b.pdf

2N3904 – Small Signal NPN Transistor
https://www.sparkfun.com/datasheets/Components/2N3904.pdf

2N5088 – Amplifier Transistors
http://www.onsemi.com/pub_link/Collateral/2N5088-D.PDF

MPSA18 – General Purpose Amplifier
http://www.redrok.com/NPN_MPSA18_45V_100mA_0.625W_Hfe400_TO-92.pdf

Burr Brown OPA2134 – Dual High Performance Audio Op-Amps
http://www.ti.com.cn/cn/lit/ds/symlink/opa2134.pdf

LM386 – Audio Power Amplifier
http://www.ti.com/lit/ds/symlink/lm386.pdf

JRC386 – Audio Power Amplifier
http://pdf.datasheetcatalog.com/datasheet/newjapanradio/de05001.pdf

LM324N – Quad Op-Amp
http://www.ti.com/lit/ds/symlink/lm124-n.pdf

JRC4558D – Dual Op-Amp
http://www.popular-hifi.com/shack/acc_renkforce_esa9/jrc4558.pdf

TDA2050 – Power-Amplifier
http://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier/TDA2050-Datasheet.pdf

LM3886 – Power-Amplifier
http://www.ti.com/lit/ds/symlink/lm3886.pdf

We are also going to be working with Raspberry Pi, Arduino Uno and Zilog Z80.

Stay tuned to find out about our projects that make use of all these components.

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