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mopie992
Joined: Dec 17, 2016 Posts: 6 Location: Ohio
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gdavis
Joined: Feb 27, 2013 Posts: 359 Location: San Diego
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Posted: Tue Dec 27, 2016 2:29 pm Post subject:
Re: CV question |
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mopie992 wrote: |
1) is CV and VCO the same thing? (http://learningaboutelectronics.com/Articles/Voltage-controlled-oscillator-VCO-circuit-with-a-555-timer.php) |
No, they're not the same thing.
CV stands for Control Voltage. It is a signal that is used to control some parameter of a device.
VCO stands for Voltage Controlled Oscillator. The oscillator circuit generates a basic wave form like a triangle or saw tooth wave.
The frequency of the VCO is controlled by providing it a CV. The higher the CV, the higher the pitch (usually).
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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? |
The CV notations are simply a schematic convention called "labels". Any wires that have the same label should be connected together. It's just a way to clean up the schematic, making it easier to read without a bunch of lines going all over the place.
In your schematic, the cathodes of the diodes, pin 7 of the 555 and R1 should all be connected together. In this case, the schematic is simple enough that they could have just as well been connected by a line, but in more complex schematics, using labels can really make things easier to read.
Quote: | 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? |
The simplest answer to this is to ask the person that bent it. There are no rules when it comes to circuit bending, I think that's kind of the point.
Though I suspect you're talking about toys that make a sound and take some sort of input to control them? First thing you need to do is get the concept of input and output straight. A CV output generates a CV that is provided to something else. A CV input receives a CV from another source, allowing the circuit to respond to it in some way. Think of the signal as traveling from the output to the input.
So a toy that makes sounds and has been bent with a pitch CV input would need a CV source (keyboard, sequencer etc) connected to it to control the pitch that way.
Hope that helps.
Gary _________________ My synth build blog: http://gndsynth.blogspot.com/ |
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mopie992
Joined: Dec 17, 2016 Posts: 6 Location: Ohio
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Posted: Wed Dec 28, 2016 10:28 am Post subject:
Re: CV question |
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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 |
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gdavis
Joined: Feb 27, 2013 Posts: 359 Location: San Diego
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Posted: Wed Dec 28, 2016 11:33 am Post subject:
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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. _________________ My synth build blog: http://gndsynth.blogspot.com/ |
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mopie992
Joined: Dec 17, 2016 Posts: 6 Location: Ohio
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Posted: Wed Dec 28, 2016 11:49 am Post subject:
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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 |
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gdavis
Joined: Feb 27, 2013 Posts: 359 Location: San Diego
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Posted: Wed Dec 28, 2016 1:40 pm Post subject:
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Ah ok. Ya, you've got it a little backwards 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. _________________ My synth build blog: http://gndsynth.blogspot.com/ |
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