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<p>Hi Benjamin,</p>
<p>thanks for your kind response. That is some useful info already.<br>
I suspected the use of a counter and logic already based on the
rhythms that came out of the thing and Twin-T was something I
suspected based on the sounds. But the noise circuit would have
been a hard guess.</p>
<p>The sounds being toy-like is somewhat of the appeal in my case
(for the person who asked me to mod it), but I am unhappy with the
undercomplex rhythms. This should be a matter of figuring out
where to inject trigger signals and coming up with a control
scheme for it. Since everybody and their dog are doing euclidian
rhythms for a while now I wanted to revive the idea of the Relabi
pattern (<a moz-do-not-send="true"
href="https://www.johnberndt.org/relabi/Relabi_essay.htm">Relabi:
Patterns of the Self-Erasing Pulse</a>, John Berndt, August
2009) for an experiment with this. Maybe with repeatable seed
values and potential auto-reset.</p>
<p>I guess I will just have to trace the circuit out then. Maybe
something to do over the Christmas break.</p>
<p>Your idea of a use of the case for your own purpose sounds
interesting as well. Should I come up with a schematic I will make
sure to share it here as well.</p>
<p>Greets,</p>
<p>David/atoav</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 2025-11-24 12:52, Benjamin Tremblay
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:6415E9E5-737A-472B-957D-A5B0A4394AED@me.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div>I never found a schematic. But the circuit is not hard to
trace.</div>
<div>The ic is a 4017, producing 6-8 step sequences. The kick drum
and other drum circuits are very typical twin t circuits. The
snare is just a tom tom sound, no white noise of its own. The
hi-hat/shaker sound uses a coil like the Boss DR-55 to produce
that whistling blue noise. In my experience with 2 of these
machines there is a wide range of deviations between components
and sound quality, and the trim pots are not enough to get
things sounding nice. It’s a toy basically and the kick drum has
no kick. I designed a pcb with some of the Monotribe drum voices
and room for a Xiao type microcontroller to fit in the enclosure
but I have not gotten around to trying it out. This is because
the new circuits would require a better power supply than a 9v
battery and it just seemed like too much love for such a low
quality toy. </div>
<div>But winter is coming so I may need a small project like this
to keep me busy. (In particular the Monotribe kick drum sound
and snare would help the CRM-260. I have a mod to extend decay
on the kick and add swept pitch but it’s a half sine wave sound
that is quite nasty.)</div>
<br id="lineBreakAtBeginningOfSignature">
<div dir="ltr">Benjamin Tremblay</div>
<div dir="ltr"><br>
<blockquote type="cite">On Nov 24, 2025, at 6:02 AM, David Huss
via Synth-diy <a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a> wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<meta http-equiv="content-type"
content="text/html; charset=UTF-8">
<p>Hi,<br>
<br>
I have a AK Drummer (CRM-260) Rhythm Machine and I am
looking for a schematic. </p>
<p>I searched the web high and low. I figured out that this
was also sold under the names Conrad CRM‑260 or CORT CRM-260
in what seems to be identical devices (apart from the
different manufacturer logo). </p>
<p>I found <a moz-do-not-send="true"
href="https://www.youtube.com/watch?v=9z71-mFVPcs">a 10
year old youtube video</a> where someone has moded the
thing, but there is no description and in a comment from 5
years ago they say the documentation has been lost. </p>
<p>Does anyone know a thing?<br>
<br>
All the best,</p>
<p>David/atoav</p>
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