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 Forum index » DIY Hardware and Software » Developers' Corner
4-Step Arpeggiator
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joshco



Joined: Nov 14, 2008
Posts: 55
Location: germany

PostPosted: Thu Aug 10, 2017 9:06 am    Post subject: 4-Step Arpeggiator
Subject description: Based on Baby10/4017
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Hi,

Currently I´m building a new synth project. This is an arpeggiator based on Baby 10. I have already ordered some PCB´s (Rev1).

In general these are two 4-Step Sequencer which are linked to each other.
The first four step sequence is transposed by a second four step row. The reset signal of the first sequencer clocks the second sequencer.

Its possible to use panel mounted Mute switches for the notes (and Transpose) Steps.

A switch determines the length for the arpeggio, either 3 or 2 Steps.

CV output is opamp buffered, the LED´s and gate outputs are buffered by ULN arrays.

Ideas and corrections are welcome!

Its a project for private use but i´m willing to share files and gerbers if wanted...(need rework at the moment)

Best regards
T.


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Last edited by joshco on Thu Aug 10, 2017 9:19 am; edited 3 times in total
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joshco



Joined: Nov 14, 2008
Posts: 55
Location: germany

PostPosted: Thu Aug 10, 2017 9:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Rev1 PCB


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Grumble



Joined: Nov 23, 2015
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PostPosted: Sat Aug 12, 2017 1:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

on IC4 pins 11 & 14 are both marked STEP3, is this ok?
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joshco



Joined: Nov 14, 2008
Posts: 55
Location: germany

PostPosted: Sun Aug 13, 2017 9:17 am    Post subject: Reply with quote  Mark this post and the followings unread

Grumble wrote:
on IC4 pins 11 & 14 are both marked STEP3, is this ok?


Fortunately it was an false label, the connection is correct.
There are the summing diodes missing in the schematic. They need to be installed on the wiper of the pots, to stay on the safe side.
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helge-h



Joined: Jun 17, 2014
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Location: Norway

PostPosted: Sun Aug 13, 2017 12:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

The output op amp looks wrong to me, you should put a resistor between pins 1 and 6 and between pins 6 and 7. 10 k would probably be correct, same as the other op amp just before it.
You should also be careful not to short any output pins on the 4017 in relation to the reset pin - it looks like there could be some trouble there the way its drawn now.

Helge
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Grumble



Joined: Nov 23, 2015
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PostPosted: Mon Aug 14, 2017 12:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Like what Helge says, look at this:
Posted Image, might have been reduced in size. Click Image to view fullscreen.
source: https://www.gearslutz.com/board/geekslutz-forum/937977-help-simple-stereo-mixer-design.html

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joshco



Joined: Nov 14, 2008
Posts: 55
Location: germany

PostPosted: Tue Aug 15, 2017 10:54 am    Post subject: Reply with quote  Mark this post and the followings unread

helge-h wrote:
The output op amp looks wrong to me, you should put a resistor between pins 1 and 6 and between pins 6 and 7. 10 k would probably be correct, same as the other op amp just before it.
You should also be careful not to short any output pins on the 4017 in relation to the reset pin - it looks like there could be some trouble there the way its drawn now.

Helge


Ok, thanks. I wanted to go low parts count on this board. I will check the opamp layout.
It seems that the reset pin should tied to ground with resistor and/or also blocked with diodes if i understand you correctly.
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joshco



Joined: Nov 14, 2008
Posts: 55
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PostPosted: Wed Aug 23, 2017 11:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Another update:
With protection diodes, pull down resistor on reset input, DC blocking cap and an additional CV input for transposing the ARP sequence externally.
I´m still waiting for the prototype boards before I post the Layout files.

Controls and Labels are:
Gate: Gate output of Arpeggio
CV: CV Notes of Arpeggio
In: Transpose CV input
Arp Length: Switch to select between 4,3, or 2 step Arpeggio
Arp Pots: CV Notes
Arp Led: Indicator of Arpeggio steps
Transpose Length: Switch to select between 4,3, or 2 step Transpose Sequence
SEQ Led: Indicator of transpose sequence steps
SEQ Pot: Notes to transpose the Arpeggio


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joshco



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PostPosted: Wed Aug 23, 2017 11:55 am    Post subject: Reply with quote  Mark this post and the followings unread

and the current pcb...(little messy since some parts were added afterwards, but its still low parts count. The diodes on the transpose pots need to be soldered directly to the lugs)


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