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teddexter
Joined: Feb 27, 2009 Posts: 9 Location: Leicester
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slacker
Joined: Nov 18, 2007 Posts: 301 Location: England
Audio files: 11
G2 patch files: 1
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Posted: Wed Jun 17, 2009 10:50 am Post subject:
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Welcome aboard
CD4049s and CD4069s are very similar so most of the time if a design uses one you can substitute the other, especially using them for audio. The chips are physically different, so aren't directly interchangeable, but if you're making your own layouts that's not a problem.
To drive CMOS chips you need to get the signal up to a level where's it's swinging between ground and whatever the supply voltage is. You might be able to do that by sticking a couple of CD4049/4069 stages in series.
A really easy way to do it is to use an LM386 as a preamp that will easily drive CMOS chips. Have a look at the PWM from here as an example.
If you don't mind using opamps, I designed an octave down pedal that used an opamp front end to drive a CMOS divider chip. The schematic and stuff is here. Just use the first 3 opamp stages, the first one gives a nice boost, the second filters the signal to improve tracking and the third stage is a comparator to give a nice solid square wave signal to drive the CMOS.
Hope that helps |
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teddexter
Joined: Feb 27, 2009 Posts: 9 Location: Leicester
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Posted: Thu Jun 18, 2009 12:32 am Post subject:
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Thanks Slacker the LM386 circuit looks to be right up my street as its simple. The Nicolas Collins book gives an example of LM386 power amp and I wasn't sure if it would be too powerful as a preamp (somehow) so I'm sure that will give the necessary "oomph" required. I'll give this one a go and report back (like the pwm feature too). Your second link seems to have expired though (have you got another source for that?).
Cheers
Ted |
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teddexter
Joined: Feb 27, 2009 Posts: 9 Location: Leicester
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Posted: Thu Jun 18, 2009 1:11 am Post subject:
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Also Nicolas Collins book talks about using CD4040 for octave divisions of a guitar fed into a 4049 for example (his circuits are very lunettarie), which is pretty cool, but was wondering if there is an easy way to divide the frequency to get notes other than an octave apart and even turn notes into chords. I suspect I may be getting into somewhat trickier territory here.
Ted |
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teddexter
Joined: Feb 27, 2009 Posts: 9 Location: Leicester
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Posted: Thu Jun 18, 2009 7:28 am Post subject:
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That post for the octave pedal is working now thanks. Also nice and straightforward. I geuss I could use just the first two stages even and get something that sounds rougher. I kind of like noise sounds. I'll let you know what I go with.
Cheers
Ted |
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slacker
Joined: Nov 18, 2007 Posts: 301 Location: England
Audio files: 11
G2 patch files: 1
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Posted: Thu Jun 18, 2009 10:33 am Post subject:
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I don't know what was up with the link, it wouldn't work for me earlier either.
Here's a direct link to the schematic in case it goes funny again http://www.eskimo.plus.com/fxstuff/slacktave.png
If you want non octave divisions you can use a CD4017 counter, with that you can get 1 and 2 octaves down and 1 and 2 octaves + a 4th below.
If you want other divisions it gets trickier, you need to multiply up the signal and then divide it.
There's some posts here somewhere about doing it. |
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teddexter
Joined: Feb 27, 2009 Posts: 9 Location: Leicester
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Posted: Fri Jun 19, 2009 1:10 am Post subject:
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slacker
Joined: Nov 18, 2007 Posts: 301 Location: England
Audio files: 11
G2 patch files: 1
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Posted: Fri Jun 19, 2009 1:08 pm Post subject:
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Yeah you're right it could
A while ago I tried hooking my guitar up to my Lunetta which has a version of the "multidivide" circuit it in and it does sound a bit like an arpeggiator. |
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