Re: [sdiy] Another Sequencer Q

[Roman]

Let's assume you have 2 separate sequencers with 555, 193 and 138 each.
To make them work in series, I'd suggest the following:
connect 4 outputs of 1st 193 counter to P inputs of the second one respectively Q0 to P0, Q1 to P1 etc.. Connect Q3 (pin7) of 193 counter via 2k resistor to negative enable of 2nd 138 decoder (pin4) tied together with middle contact of 1st section of DPDT. Lower contact of the same section connect to enable of 2nd 138 (pin6), upper to GND.
Second section of DPDT is simpler. Middle goes to GND, lower to parallel load of second 193 counter (pin11).

When DPDT lever in the up position, they will work as 16-step sequencer. When it's in the bottom position, they will work independent.

If you choose HC series instead of LS (less current, same fuctionality) you can use 10k instead of 2k mentioned, but you also need to add 100k pullups on pin 6 of 1st 138, and pin 11 of 2nd 193.

Hope that helps.
If not, I'll draw a schematic
Roman

---- Wiadomość Oryginalna ----
Od: Pat Kammerer <spivkurl at wearerecords.com>
Do: sdiy <synth-diy at dropmix.xs4all.nl>
Data: Thu, 17 Jun 2004 23:39:11 -0500
Temat: [sdiy] Another Sequencer Q

>Thanks to everyone who helped with my previous question on distribution.
>
>Now I'm wondering about modifications to the basic circuit.
>
>The sequencer is pretty basic with a 555 acting as clock for a74ls193
>up/down counter which drives a 74ls138 demultiplexer.  I want to make two 8
>step sequencers for a bit of a controller module (with some LFO's and
>sample/hold too), but I would like to have a switch which puts them in
>series to make a seamless 16 step sequencer.  I've been thinking it could be
>done with another 555 triggering the clocks, or some sort of schmidt trigger
>on the last step... but, since these digital things are a bit beyond my
>grasp, I'm not sure how to design this part.  (I am trying to learn...)
>
>I'm sure there's a way.  Thank you.
>Pat
>
>