Switching Signals using momentaries, sequential switches...

fonik · Last edited by fonik on Wed Apr 01, 2009 2:06 am; edited 6 times in total

This is what i'd liked to do: i wanted to have one momentary switch on the frontpanel to step thru i.e. different waveforms or channels or whatever. the active channel would be indicated by a LED. i know this could easily be done using a double pole rotary, but i want a momentary.

my idea was to use a 4017 clocked by the debounced momentary. the outputs of the 4017 would then control SPST ICs (i.e. the MAX313 rom maxims).

for 4 channels with LEDs i would need the 4017 and 2x MAX313.

any ideas how to do it easier or with less ICs?

[EDIT: uploaded the final schematic providing all bells and whistles]

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Inventor · Posted: Fri Jan 09, 2009 7:40 pm Post subject:

That sounds like the way to do it! I suppose you'll want to put an LED on each output, no doubt that was your plan, eh?

fonik · Posted: Fri Jan 09, 2009 7:51 pm Post subject:

Inventor · Posted: Fri Jan 09, 2009 8:17 pm Post subject:

Too bad there isn't an counter with open collector outputs or open drain outputs, then you could just shunt the signals quiet except for the active one. Might get some leakage though.

You could use a PIC to do that in a variety of different ways, perhaps.

I dunno, just thinking out loud.

RF · Posted: Fri Jan 09, 2009 8:51 pm Post subject:

Is there is a way to initially load one bit into a shift register (ie. 4015) send the output back into the input and use your momentary switch as the clock? scratch

bruce

Inventor · Posted: Sat Jan 10, 2009 3:38 am Post subject:

fonik · Posted: Sat Jan 10, 2009 6:57 am Post subject:

Uncle Krunkus · Posted: Sat Jan 10, 2009 7:09 am Post subject:

Wouldn't a 4024 need a separate B to D for the LED indicators?

Inventor · Posted: Sat Jan 10, 2009 7:17 am Post subject:

Inventor · Posted: Sat Jan 10, 2009 7:20 am Post subject:

You could also play games with opamps, like this. Sum the digital output into the oscillator signal with gain. Then when the output is one, the opamp will hit the rail and no oscillator signal will get out, and when the output is zero you get your signal. If you have to have an opamp there anyway there are no added parts.

blue hell · Posted: Sat Jan 10, 2009 7:21 am Post subject:

fonik · Posted: Sat Jan 10, 2009 7:29 am Post subject:

blue hell · Posted: Sat Jan 10, 2009 7:37 am Post subject:

richardc64 · Posted: Sat Jan 10, 2009 8:15 am Post subject:

fonik · Posted: Sun Jan 11, 2009 5:29 am Post subject:

blue hell · Posted: Sun Jan 11, 2009 5:33 am Post subject:

fonik · Posted: Sun Jan 11, 2009 10:08 am Post subject:

Scott Stites · Posted: Sun Jan 11, 2009 4:16 pm Post subject:

Playing the feature creep for a moment. Oh, hell, who's pretending? Very Happy

Why use that counter? The CD4516 was built to make stuff like this much more versatile.

I know you said "simple", but it wouldn't take a whole lot of surgery to make this really kick.

A CD4516 would allow you to count up and count down. You could also jam an input in, so you wouldn't have to work sequentially. Each channel could have its own momentary - you could jump from channel 2 to channel 4, for example, or 3 to 2, just by pushing the associated switch. Creeping forward from that, each channel could have its own pulse input so you could automate that process. Forward/reverse could be a switch.

I'd use a diode matrix for the momentary inputs for the jamming, but you could use a priority encoder, too, which is, of course, another IC.

Back under the rock....

Cheerios,
Scott

Scott Stites · Posted: Sun Jan 11, 2009 5:08 pm Post subject:

Here's what I'm thinking about - it's a rough draft of the concept. Dunno if it works exactly as drawn (capacitor value might need played with) and debouncing would need to be addressed. I think reverse would be gilding the lily, but individual selection would be great - you could pre-patch stuff and select among things. Especially the way you patch up things like that (I'm thinking of those Klee videos and samples).

Cheerios,
Scott

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Scott Stites · Posted: Sun Jan 11, 2009 5:55 pm Post subject:

Here's an implementation that would allow external signals to select any of the four channels arbitrarily.

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fonik · Posted: Mon Jan 12, 2009 10:13 am Post subject:

scott, you are driving me crazy! first i had an idea how to do something i want - then do you taking this far beyond with such nice ideas, and now i am thinking of how to use this for my synth Shocked

honestly a great idea. i will see how this fits in my UI concept (big words Embarassed

).

Scott Stites · Posted: Mon Jan 12, 2009 12:09 pm Post subject:

Hey! You started it by posting that juicy schematic. Laughing

Sorry about that - there's something about CMOS that is just so endless. It's the true Tinkertoys of Synth DIY. I never know where/when to stop....

Anyway, whatever you come up with, I bet it'll be awesome.

Cheerios,
Scott

Inventor · Posted: Tue Jan 13, 2009 10:10 pm Post subject:

You know, this isn't schmooze, but I just thought I'd mention that I once had a cat named CMOS. CMOS was black and white and a very smart cat. I once observed her watching a geometry show on public television with fascination.

I think if CMOS were still with us, she'd be watching the LED's and wondering what made them blink! Haha, now back to your design fun, folks...

fonik · Posted: Wed Jan 14, 2009 4:45 am Post subject:

actually OT, however:
here is the updated schematic of the VC sequential switch. i simplified and corrected the LED circuitry as mentioned, and added two switches:

SW1 selects the powering of the 4052. when powered from -8V to +8V it is in bipolar mode for audio and LFO, when powered from GND to +15V it is for clock and envelopes. you could process clock and envelopes in bipolar mode, too, as long as you assure not to exceed the limits (however there are protecting diodes on the I/O's).

SW2 routes the 8V from the LEDs to the reset of the CD4024, thus allowing to change the number of steps (2, 3 or 4). is the diode really needed (a proposal from peter grenader)?

i am now thinking about a manual reset switch (momentary). would it be sufficient to wire the momentary to +8V?

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blue hell · Posted: Wed Jan 14, 2009 6:25 am Post subject:

I see a small problem Wink

When Q2 conducts and IC4 happens to be in such a state that LED3 or LED4 are on and SW2 is in the right position too ... there is a short circuit from +V8 to GND .. maybe move R11 to the other side of IC4?