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Blue Hell
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Joined: Apr 03, 2004 Posts: 22431 Location: The Netherlands, Enschede
Audio files: 216
G2 patch files: 319
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Posted: Thu Dec 07, 2017 4:10 pm Post subject:
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chatted a bit with wmonk about this puzzle ... maybe it gives some ideas?
Code: | [22:49:40] Jan for .. whenyou like a puzzle ... :: http://electro-music.com/forum/post-431923.html#431923
[22:52:37] wmonk oh, he is confusing pin numbers with output numbers, it seems
[22:52:39] wmonk
[22:52:51] wmonk probably a short somewhere too
[22:52:56] Jan heh .. dont think so
[22:53:23] wmonk and rotary switches, they work in mirror, or something like that
[22:53:28] Jan he mentions bothdivision rate and pin number in some posts - correctly
[22:54:00] Jan actually one of the few people posting accurately about experiments
[22:54:11] Jan or - seemingly so
[22:54:40] wmonk hmm
[22:54:47] wmonk oh, he used +/- 6V signals
[22:54:56] wmonk on a chip thats powered from 0 - 15V
[22:55:03] wmonk most chips dont like that
[22:55:23] Jan clipped in the input circuits
[22:55:32] wmonk oh yeah
[22:56:23] [INFO] Font size is 7pt
[22:56:31] [INFO] Font size is 9pt
[22:56:50] wmonk the +/-3V square wave... hmm, that might be a gain of the schmitt trigger problem
[22:57:07] Jan yeah that may be a tad low
[22:57:40] wmonk I have that thing in my modular
[22:57:45] wmonk the yusynth clock dividers
[22:57:50] wmonk no problems whatsoever
[22:57:51] Jan ah
[22:58:00] Jan designseems solid tome
[22:58:21] wmonk I used the PCB layout of his website though
[22:58:35] Jan he is breading it
[22:59:36] Jan now in most cases .. when it dont work .. the circuit is not what you thinkit to be ... but cant come up with a model
[22:59:45] wmonk aha
[23:01:18] wmonk looking at datasheet and schematic
[23:01:45] Jan Ihave the COS/MOS book on the tab;e too
[23:01:48] wmonk pinout in schematic is correct according to datasheet
[23:02:02] Jan andhad checked that as well
[23:02:06] wmonk so either there is some floating CMOS input pin
[23:02:14] wmonk not that hard on a breadboard
[23:02:28] Jan yeahcould be .. but allthree behave the same he sez
[23:02:52] wmonk in that case its three times the same error
[23:03:06] wmonk not that hard on breadboard either
[23:03:09] Jan een ezel in het algemeen
[23:03:30] wmonk if you are convinced something is good, it usually isnt
[23:03:40] Jan yeah - could be
[23:04:00] Jan whenit was copied over section by section
[23:04:17] wmonk diodes reversed would fuck it up too
[23:04:26] Jan he checked those
[23:04:47] wmonk and rotarty switches are evil, how you need to wire those
[23:04:59] Jan sometimes yes
[23:05:09] Jan but he works with wires
[23:05:32] Jan bypassingthe switches .. or .. replacing .. I hope
[23:05:49] Jan and assume
[23:06:31] wmonk 100nFs in place as close as possible to the chip?
[23:06:41] Jan I think you are right about some fuckup in the breading
[23:06:42] wmonk especially with breadboards
[23:07:06] Jan yeah could be .. or grounding was my latest - and last prolly - idea
[23:07:44] Jan oh damn .. some breads dont have continues power rails
[23:07:54] Jan you needto patch those
[23:08:02] wmonk yup
[23:08:21] Jan going topaste this discussion intothat thread, ok?
[23:08:40] wmonk sure
[23:08:44] Jan k |
_________________ Jan |
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flagada
Joined: Dec 15, 2016 Posts: 13 Location: Amsterdam
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Posted: Fri Dec 08, 2017 12:06 am Post subject:
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Hi Jan, thanks for thinking along and trying to find help! But I think I have found the reason for the strange behaviour. Btw: I built it on stripboard (veroboard), not on a breadboard.
I recently built the MFOS 32 step sequencer, and Ray was talking about a strange reset at some pin that he could remove by adding a 1nF cap to ground (he called it a glitch removal cap). So I took out a 1nF cap and... Bingo!
When I add a 1nF cap between pin 7 and ground, the strange behaviour is gone! (pin 7 is were the 3rd division is, just before the 4th were things go wrong).
Then I noticed that 1 of the dividers was still acting strange, even with the cap. The only difference was that it's tracks were longer than those of the other two.
I has to do with stripboard, and the fact that adjacent strips/tracks can influence each other, especially when those tracks are long. For instance by forming a capacitor, resulting in stray capacitance. But I guess that there are more effects that can occur like sensitive parts picking up electric fields. I have built many circuits on stripboard and two times before I have had issues that could be solved by minimizing the length of the tracks.
So now I have shortened the track were pin 7 is soldered as much as possible. I only could shorten it by 0,75 cm, but the total length was only 1,5 cm so I effectively cut it in two. And now, all three dividers work normal, even without the 1nF cap! That is, with the +6 Volt gates. Fingers crossed: I still have to put the switches and the wires back in place.  |
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Blue Hell
Site Admin

Joined: Apr 03, 2004 Posts: 22431 Location: The Netherlands, Enschede
Audio files: 216
G2 patch files: 319
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Posted: Fri Dec 08, 2017 5:25 am Post subject:
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Great :-)
And re. the strip board turning into a bread board .. that's what happens with chinese whispering! _________________ Jan |
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