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<DIV><FONT face=Arial size=2>Assuming the 24ppq pulse is 50% dutycycle
generating a short pulse on very hi/low and low /hi transition as you propose
seems a usable method.</FONT></DIV>
<DIV><FONT face=Arial size=2>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The bad news; most probably your 24ppq clock
pulse is not 50% dutycycle :(</FONT></DIV>
<DIV><FONT face=Arial size=2>Therefore IMO your best option might be to use a
PLL circuit like a 4046.</FONT></DIV>
<DIV><FONT face=Arial size=2>The data sheet will show you the circuit because
this is a typical application for a 4046 :)</FONT></DIV></FONT></DIV>
<DIV><FONT face=Arial size=2>Down side of this solution is that the PLL might
need some time to lock to a (sudden) tempo change.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>However when your 24ppq clock is indeed
symmetrical, generating pulses on every transition is indeed a
option.</FONT></DIV>
<DIV><FONT face=Arial size=2>The advantage would be that is doesn't have
tracking problems when the tempo changes.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>You can do this quite easy with 3 Schmitt
trigger gates like those in the 4093.</FONT></DIV>
<DIV><FONT face=Arial size=2>The data sheet for the CD4093 on the
Fairchild-semiconductor website shows how to make a negative triggered "gated
one shot".</FONT></DIV>
<DIV><FONT face=Arial size=2>You need two of these, one you feed with the 24ppq
pulse the other with the inverse of the 24ppq pulse.</FONT></DIV>
<DIV><FONT face=Arial size=2>The output of the "one shot" circuits can be added
together with 2 diodes and a 33k resistor to ground where the diodes
meet.</FONT></DIV>
<DIV><FONT face=Arial size=2>Basically you now have your 48ppq pulse, but
it might be a good idea to buffer this signal.</FONT></DIV>
<DIV><FONT face=Arial size=2>One way to do this is to send it though the
left over 4th gate in the 4093</FONT><FONT face=Arial size=2>. </FONT></DIV>
<DIV><FONT face=Arial size=2>The 4093 gate inverts the signal therefore
you need to add a second inverting circuit as output
buffer.</FONT></DIV>
<DIV><FONT face=Arial size=2>Otherwise your 48ppq clock would run slightly
"late".</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>HTH</FONT></DIV>
<DIV><FONT face=Arial size=2>Theo</FONT></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A href="mailto:E.B.Smits@chello.nl" title=E.B.Smits@chello.nl>E.B.S.</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
href="mailto:synth-diy@dropmix.xs4all.nl"
title=synth-diy@dropmix.xs4all.nl>synth-diy@dropmix.xs4all.nl</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, October 28, 2002 4:40
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [sdiy] 24 --> 48 PPQ double
clock pulse</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>
<DIV><FONT face=Arial size=2>Hi everyone,</FONT></DIV>
<DIV><FONT face=Arial size=2>I just subscribed again after a few years. Is the
list still active? This list helped me great in the past and now i have a
question.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Last week a bought a Linndrum and already
like it alot. To sync it to other devices there is a clock in and out. I
allready found out it runs on 48 PPQ (pulses per quarter measure). My problem
is that the rest of my drummachines run on 24 PPQ (roland boxes) so i would
like to double the pulse rate.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Is there a simple circuit that can do this?
</FONT></DIV>
<DIV><FONT face=Arial size=2>I thought of something that outputs a pulse on
the start and end of the 24PPQ pulse but i don't know how to implement
this. Are there any other (better) alternatives? </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Any help would be much appreciated.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks in advance.</FONT></DIV>
<DIV><FONT face=Arial size=2>Greetings,</FONT></DIV>
<DIV><FONT face=Arial size=2>Eric (Amsterdam)</FONT></DIV>
<DIV><FONT face=Arial
size=2></FONT> </DIV></FONT></DIV></BLOCKQUOTE></BODY></HTML>