CV question

mopie992 · Joined: Dec 17, 2016 Posts: 6 Location: Ohio

Hello again
I've found a number of schematics for building 8 and 16 step sequencers, but many have "CV" as an input (output?) and 99% of the time it is just stated.. input a CV. or "I have modified/bent a toy as the CV" without going into it much.
I have read and am still a tad confused...

ok so my questions:

1) is CV and VCO the same thing? (http://learningaboutelectronics.com/Articles/Voltage-controlled-oscillator-VCO-circuit-with-a-555-timer.php)

2) on the schematic I have attached here, are the 2 CV notations stating these are connected (as in the 555 is the CV?)? or is the external CV going to both connections?

3) if i have a bent toy (and I have a number of them, mostly Pitch bends and static makers, but you get the idea) how does one know if that output is CV?

thanks!

theMopie

complete_sch.png

Description:

8 step sequencer schematic

Filesize:

14.33 KB

Viewed:

252 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

gdavis · Posted: Tue Dec 27, 2016 2:29 pm Post subject: Re: CV question

mopie992 · Joined: Dec 17, 2016 Posts: 6 Location: Ohio

Thanks Gary this helps!
Of course this begs more questions though...

Say i wanted to use a toy that I have bent as the CV for this sequencer (opposed to the 555 oscillator in the schematic originally attached).
I have searched for CV circuit, but came up with mostly goose eggs or VCO schematics, so I guess the main question is how do you build/create a CV?

I suspect this is not the right question, but I'm learning so any help is appreciated

I have built this sequencer and a few others but they all run off their own oscillators and have no external inputs. I have tried to put an APC in, but again I don't know how to know if that qualifies as a CV.

thanks in advance.

theMopie

gdavis · Posted: Wed Dec 28, 2016 11:33 am Post subject:

It sounds like you've still got things a little backwards. The sequencer is generally a CV source, you don't send a CV to it. Unless there is some parameter of the sequencer you want to have under CV control? There are two 555 oscillators in the circuit so I'm not sure which one you're referring to. It might help if you asked questions in terms of what you want to accomplish instead of terms you may not quite understand.

Honestly this isn't a very good circuit to use as a study of CV as it doesn't actually use any CV's. Even the parts labeled as "CV" aren't actually a CV.

Generating a CV can be quite simple, often a pot set up as a voltage divider is all that is needed. However, adding the ability to control a circuit with CV when the circuit doesn't already work on CV's is not trivial, it's usually much more difficult than people realize.

Oh, and I don't know what an APC is.

mopie992 · Joined: Dec 17, 2016 Posts: 6 Location: Ohio

It is common for me to try to run before I can walk, but then again falling down means you get to get back up again right?

Ok I have built a few sequencers based on 4017 & 555s as well as CasperElectronic's 40610/4040/4015 (http://casperelectronics.com/finished-pieces/omsynth-minilab/omsynth-video-tutorials/video-2-sequencers/.. He has 3 superb tutorial videos)

What I would like to do is have the steps of the sequencer be the sound a bent toy. I have a a number of bent kids toys that make great sounds and noise, so if i could have those sounds in the sequencer (and control the pitch of each with the pot per step) that could be a fun noise maker/sequencer . i think.
So thats probably why I have the concept a bit backwards... I'm thinking linearly -> Bent toy -> sequencer -> speaker.

APC- Atari Punk Console, this was the starting point of my noise making journey.

thanks again

theMopie

gdavis · Posted: Wed Dec 28, 2016 1:40 pm Post subject:

Ah ok. Ya, you've got it a little backwards Smile

I think what may be confusing you is that some of the sequencers you're looking at also include an oscillator to make sound, so they are really two things in one - sequencer and sound source. What you want is the toy is making the sounds, with the sequencer controlling the pitch of the toy. The toy is replacing the sound oscillator.

So it would be sequencer -> bent toy -> speaker.

The sequencer is the CV source. It outputs it's CV to the toys CV input. The toy responds to that CV by varying it's pitch accordingly. The toy outputs it's sound to the speaker.

I'm assuming the toy has been bent to add a CV input.

The circuit you originally posted isn't quite suitable for this. It could be modified to work, but if you've already built another more suitable sequencer, may as well use that.

The last circuit in the Casper page you linked, "8 STEP VOLTAGE SEQUENCER" should work. It is generating a CV output that you could connect to your toy.

The wire labeled "sequenced voltage out..." is the CV output which would be connected to the CV input of the toy. You would also want to connect the toys ground to the ground of the sequencer. Powering the sequencer from the toys power may be a good idea as well, but I'd need more information to know exactly. As long as their grounds are connected and the sequencer is powered from 5V to 9V you'll likely be OK.