Maplin E&MM Harmony generator

[Matt the Modulator]

i bought an unmade maplin E&MM harmony generator a few years ago and ive only just got it working. it produces a square waveform that is a 5th / 3rd or octave (-3 to x3 octaves) of the input signal which must be a simple monophonic waveform with little or no modulation
ive done a little vid of it using a LSDJ -gameboy

E&MM Maplin Harmony generator

more infor and schematic of the unit can be found below  maplin no longer stock the ic's but farnell and rapid do.

http://www.flickr.com/photos/matt_the_modulator/sets/72157622340629246/

[Circuitbenders]

So it tracks an input signal and generates a waveform thats a certain harmony of the input? I'd imagine that its part of one of those mammoth Maplins E&MM analogue synths they used to sell isn't it?

I can't think of a single reason why i'd need one of these, and yet strangely i must have one! 

[Matt the Modulator]

So it tracks an input signal and generates a waveform thats a certain harmony of the input? I'd imagine that its part of one of those mammoth Maplins E&MM analogue synths they used to sell isn't it?

Yeh basically thats it it tracks a waveform square and saw seem to work best it has -3 -2 -1 unison +1 +2 +3 octaves selector with either octave, 5th, or 3rd harmonics selector. it probably is part of the synth system and like the maplin synths its plaqued by bad design ive had to replace a op amp allready and change a few resistors (cant remember what i did   ) iam not surprised these things rare well working anyway.

Its a funny design as it says in the manual (link above) the best way is too feed a single  VCO directly  into the unit  then put the mixed output through the filter and vca sections but it only likes signals of about 300ma pk-pk   silly really most synth output a wopping signal at the VCO stage. (ive added a volume input pot at the back)

It can work with just a SK or SA ECT synth pugged into it as it does have a envelope follower circuit that controlls the volume enevelope of the harmony signal and a circuit that freezes the devider circuit when the signal gets low but this set up produces pitchy jumps and glitches in a nice computer voice type way very unique and you do want one i cant put it down ive had it working again for a day and ive tried every riff i can find through it

E&MM harmony gen

[noystoise]

nice! next you should try replacing the rotary octave switch with a simple six channel mixer. heres something i've been working on:
SUGAR FIRE
its a glitch toy that i ran through a comparator then a frequency divider then 1/1 and 1/8 to separate vcf's modulated by some ramps. the frequency divider circuit really adds a lot more to the glitch. it adds a lot to everything really

[Matt the Modulator]

Great tones!

iam not sure  using sliders for the octave would work as its only has one pll circuit ?? but then i dont know much about whats really going on in this thing cheers for the idea

[Gordonjcp]

*Somewhere* I have the original article from E&MM for this.