[sdiy] Re: eti 4600

[Stephen Lenham]

Hi Julian, 

First stop, if you haven't already, would be to pick up the schematics from 
the excellent Cloned Analogue Gear site: 

http://omega.tellus.vallentuna.se/anders/ 

Provided that you can source something suitable, as everything else is there 
I'd say that the easiest option is to simply fit a keyboard to your existing 
unit. The keyboard is a standard 49-note part with a single closing contact 
per key, so pretty much anything with the right span could probably be made 
to work. 

If you'd prefer to convert to CV control, the 4600 uses linear (Hz/volt) 
VCOs driven from a pseudo-digital keyboard interface generating an 
exponential control signal by switching between various taps on resistor 
chains (very much like Yamaha's monophonic CS-series synths). So you'd need 
a Hz/V capable MIDI-CV converter and would need to plumb the CV and gate 
signals into the right points, perhaps with some scaling or level-shifting. 
Looking at the schematic, that doesn't look too hard - the output of IC8 
looks like a good place to break into for the CV while the collector of Q5 
would be appropriate for the gate signal. 

Best of luck! 

Steve L. (also in the UK) 


Julian writes: 

> Hi there, 
> 
> I have an Maplins / ETI 4600.  It has no keyboard (but does have the
> keyboard controller module) 
> 
> I either need to find a keyboard (unlikely) or get it under some sort of cv
> controll. 
> 
> 
> Two things here then: 
> 
> 1) If i CV it, then theres no point in me keeping woodwork.  Wood (sorry,
> couldnt resist ;) anyone like it?  Its the standard maplins bits that they
> did at the time.  Im in england. 
> 
> 2) Anyone have any experiance of getting these under cv / midi controll?
> Any pointers to texts that i can read on the subject? 
> 
> Cheers, Julian 
> 
>