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 Forum index » DIY Hardware and Software
Simple ribbon controller for V/Hz synth
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nicolas3141



Joined: May 25, 2007
Posts: 138
Location: Christchurch, New Zealand

PostPosted: Thu Mar 05, 2009 2:24 am    Post subject: Simple ribbon controller for V/Hz synth Reply with quote  Mark this post and the followings unread

Continuing my simple synth series. Design goals: simple and educational circuit, 9V battery powered. V/Hz with CV output of about 1-5V giving at least two octaves of reasonable linearity. Stripboard layout shown with no cuts required. If you have a 5 or 6V reference voltage already available you can use that instead of C1 and U1. If you are building it into your synth you can use the main power supply instead of the battery and you won't need the stereo socket with the power-on-when-plugged-in earthing arrangement. Multiple output sockets on this can be very handy in a modular synth.

Finding suitable tape is the hardest bit. I have tested quite a few video/audio/computer-backup tapes and found that pro-grade tapes from the 80s or earlier are the most likely to be suitable (amongst older pro-grade tapes I found I needed to test about a dozen tapes to find two or three suitable ones). Modern consumer grade VHS is not so likely to be suitable. I think you want somewhere between 10K and 100K per 10cm of tape. Most tapes are more like 1M or more over that distance which is too high to be useful. I have found one oddball that was about 3K per 10cm.

One thing to note is that the contact resistance can be quite high. For example if you get a reading of 100K over 10cm, 25K of that might be the probe to tape contact resistances. So 1cm would read about 30K. This doesn't usually matter too much with a three wire voltage divider type circuits like this, but will affect the linearity slightly.

I have some quarter inch tape from a computer backup cartridge and some half inch tape from professional TV betacam that both give me a reading of just under 100K per 10cm. Both work well with 25-30cm of tape as the ribbon, but the betacam tape seems to wear out much much faster. I stick the tape down with double sided sticky tape. Long and high resistance ribbon controllers are more likely to pick up hum and noise. C3 is there to quite that down, but does slow the response slightly. You may need to adjust the value of C3. Use the smallest value that still kills the noise.

You only need to find one tape that works and it will supply you and everyone you know with ribbon controllers for the rest of your life including regular replacements of the ribbon if necessary. So if there is anyone in Christchurch, New Zealand who needs some suitable tape, feel free to contact me.

Cheers,
Nicolas


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Pehr



Joined: Aug 14, 2005
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PostPosted: Thu Mar 05, 2009 3:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Wow! Very Happy

Is it possible to make a thread with the collection of all your current and coming circuits. Or even a subforum? Very Happy

I really like these simple synth circuits. Cool

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creatorlars



Joined: Nov 26, 2007
Posts: 524
Location: Denton, TX
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PostPosted: Thu Mar 05, 2009 9:50 am    Post subject: Reply with quote  Mark this post and the followings unread

This is awesome! I have a Korg Micro-Preset that is V/Hz that needs to be recased. I tried making a ribbon controller for it before because I dislike the keyboard and wanted to turn it into a ribbon controller based synth.

I dug out all my old VHS tapes and out of 30 or 40 I only found one or two that are 10K which seem to work (except not with the Korg, being V/Hz.) Only bad thing is that it was my Peewee Herman's Christmas Special tape! Sad But now I can resurrect this project.

I second the motion for a website or single thread with all of your schematics! Information on adapting for standard modular levels/power would be great too.
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nicolas3141



Joined: May 25, 2007
Posts: 138
Location: Christchurch, New Zealand

PostPosted: Fri Mar 06, 2009 4:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Matching VCO - http://electro-music.com/forum/post-231723.html
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Dego



Joined: Apr 22, 2008
Posts: 139
Location: Sweden

PostPosted: Mon May 25, 2009 6:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Pehr wrote:
Wow! Very Happy

Is it possible to make a thread with the collection of all your current and coming circuits. Or even a subforum? Very Happy

I really like these simple synth circuits. Cool


I agree. It would be good to have them all together.

I have built the LFO, VCLFO (not tried the cv yet). I have the ADSR ready soon. Think I am going to build the filter as well. Smile
Just have to score a lm13600n first...
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Pehr



Joined: Aug 14, 2005
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PostPosted: Mon May 25, 2009 10:00 am    Post subject: Reply with quote  Mark this post and the followings unread

[quote="Dego"]
Pehr wrote:
Just have to score a lm13600n first...


doesn't the 13700 work aswell?

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Dego



Joined: Apr 22, 2008
Posts: 139
Location: Sweden

PostPosted: Mon May 25, 2009 10:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Yeah, but they are also expensive.
Mouser suggests this one as a replacement:
http://se.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMutXGli8Ay4kEnP%2fCY8WwSLRooVB6dPAf4%3d

It is much cheaper...
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radek tymecki



Joined: Mar 22, 2009
Posts: 71
Location: PL

PostPosted: Sat May 08, 2010 2:29 am    Post subject: Reply with quote  Mark this post and the followings unread

u can use also NE5517N
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nicolas3141



Joined: May 25, 2007
Posts: 138
Location: Christchurch, New Zealand

PostPosted: Sun Aug 01, 2010 2:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Here is a suggestion for how to turn this circuit into a keyboard controller. This circuit is currently completely untested.

Cheers,
Nicolas


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inlifeindeath



Joined: Apr 02, 2010
Posts: 315
Location: Albuquerque, NM

PostPosted: Mon Jan 03, 2011 5:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

just built one of these from my copy of "The Terminator"! This thing is awesome; I used a 5 volt reg and a 2n3904 and am getting just under 5 octaves on the Saw VCO. You rule Nicolas!

Which resistor would I need to sub in order to get a range control pot?
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darkomen



Joined: Jun 21, 2010
Posts: 40
Location: USA

PostPosted: Tue Apr 12, 2011 6:32 am    Post subject: Reply with quote  Mark this post and the followings unread

How would I go about adding a gate and trigger out from your ribbon (or keyboard) controller in order to work with your modules?
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inlifeindeath



Joined: Apr 02, 2010
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Location: Albuquerque, NM

PostPosted: Tue Apr 12, 2011 8:04 am    Post subject: Reply with quote  Mark this post and the followings unread

the ouput can be used as a gate signal. it will gate for as long as you hold down the string. i used it successfully on my soundlab to trigger the AR gen
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darkomen



Joined: Jun 21, 2010
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Location: USA

PostPosted: Tue Apr 12, 2011 8:53 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the reply. What about a trigger, could I use a schmitt-trigger configured as a one shot?

Also, semi-related to this thread. I see that the nicolas circuits use V/Hz, how do you determine the voltage needed to get a certain frequency?
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inlifeindeath



Joined: Apr 02, 2010
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Location: Albuquerque, NM

PostPosted: Wed Apr 13, 2011 5:53 am    Post subject: Reply with quote  Mark this post and the followings unread

try the one shot below, i would think it should work. not sure how to estimate frequency. you could always use a trim pot to change the range.


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darkomen



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PostPosted: Thu Apr 14, 2011 4:59 am    Post subject: Reply with quote  Mark this post and the followings unread

So I think I've figured out a good solution for a gate/trigger. If I have a comparator that compares the CV being played to 0V I could have it output a constant 5V for the gate as long as the note is on. For the trigger I found the CGS gate to trigger converter. I'm going to try this over the weekend to see how it work.
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darkomen



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PostPosted: Thu Apr 14, 2011 5:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Also found this one from MFOS, which uses the one-shot 40106.

http://www.musicfromouterspace.com/analogsynth_new/HOT_TIPS/PDF/gatebuffer20090923_assembly.pdf[/url]
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inlifeindeath



Joined: Apr 02, 2010
Posts: 315
Location: Albuquerque, NM

PostPosted: Tue Mar 13, 2012 10:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

just finished a dual verison. video here:http://youtu.be/rf0kp-jo_yI

better video tomorrow.

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inlifeindeath



Joined: Apr 02, 2010
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PostPosted: Wed Mar 14, 2012 11:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

fyi, used the cv output for both VCO freq and to gate a VCA, works just fine.
Also, no voltage reg.

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