[sdiy] trying to understand appregiators in late 70's synths

[Florian Anwander]

Hi Dan

> i just want to figure out how the heck to do it!! 
I think the idea for an arpeggiator came with the first matrix style 
keyboard. The arpeggio is the scan of the keyboard matrix that has to be 
done anyway, but only with a lower clock speed.

If you understood the basic principle of a matrix based keyboard, then 
you will be able to build an arpeggiator with sheer hardware too (and 
assumingly also a sequencer won't be too difficult).

In the german issue 07/08 1981 of Elektor was the schematic for a 6-Bit 
keyboard encoder. basically it is a switch matrix scanned by two 4051's.
The common-in/out of one 4051 is connected to 'high'. The common-in/out 
of the other 4051 delivers a trigger if the related key in the matrix is 
pressed.
The 4051's are addressed from an 4040. The adress bus is sent to a latch 
(two 4042's), whitch is clocked by the trigger from the matrix.

This schematic is missing only the circuit which generates a gate 
(either simply a flipflop, or something more complicated if you want an 
algorithm based gate creation).

I'll try to scan it.

Florian