i finally got the switches i was missing for my anushri today so i finished the last cosmetical changes of the build and tried to fix a small issue i have with it:
i have no -1oct sub osc signal (everything else is working perfect.)
i should mention my anushri is a late prototype (i got from fcd72 when he decided his pile of anushris was big enough after i missed the first kit run - thanks again fcd!)
it is a late revision prototype (the one with the inverted subosc level pot - mobo says rev.c , controllboard has no rev. number only says “cc-by-sa, OlivierGillet” and is yellow)
i don’t think the issue is related to that, because the routing of the -1 oct sub signal looks like it is like the final revision.
i probed the out pins of the 4024 and they all work except the /2 one which has only a faint signal which to me sounds like it is some kind of bleed through from the vco signal (does not sound lower than the vco signal.)
resistance to ground from the /2 output is the same as from /4 so i don`t think a short to ground is the problem.
what is the next step to find out, whats wrong here?
The sub-oscillator has worked on all revisions of the PCB
If you have another CD4024, try it. If you can lift the pin with the /2 signal (so that it does not touch the socket) and directly probe the pin, try it (to make sure the pin output is not shorted downstream).
same thing with upbent /2 pin.
so i guess that 4024 is kaput.
i am sure i have another one somewhere. will go on a search mission later.
thanks a lot for your help!
i did not realize it was likely only one output pin of the ic would be broken.
To late to throw one into the post for delivery tomorrow ;-(
thanks fcd, but no problem.
would have been nice though. i just found out, i only got 4040 here right now, which is basically the same thing, but with another pinout.
new 4024 solved the problem
Very odd … had the same problem, and the same solution
Can it be that a 74HC4024 (which did not work for sub-1) is not quite the same as a CD4024 (which does work for sub-1) ?
As the number implies its not the same.
The HC one is from the HiSpeed CMOS family the CD4024 is TTL. See here
Albeit they have the same functionality and pinout they have otherwise quite different Specs, its like comparing a FIAT 500 with a Maserati Grantourismo: both come from Italy, need gasoline, have 2 doors and 4 seats albeit the rest is a bit different.
Ah, thanks … I should have known … (although I would have expected the 74 series to be TTL and the CD to be CMOS ?).
I had both in my drawer, so I must have ordered the CD4024 for the Anushri, and the 74HC4024 for another project - if only I could remember which one
Looking at the BOM again: this does specify a 74HC4024 (see the Reichelt column).
Perhaps this should be updated ? The Mouser entry is for a CD4024, so that one is OK.
74HC4024 and CD4024 are both CMOS. And both should work here.
The CD4024 is required for Anushri!
Main difference is the supply voltage range:
74HC4024: 2V - 6V
CD4024: 3V - 15V
I looked at the datasheets for both, and they sure do look the same …
It could be that my (new) 74HC4024 was faulty, but there might be small differences in timing, for example.
Just had a look at the Anushri schematics. The 4024 is connected to VEE (
5V) and VCC (+5V), so we have a supply voltage of 10V. That’s to much for the 74HC4024 (specified for 2V 6V).
Conclusion: The CD4024 is required for the Anushri!
Ah … so the Reichelt column of the BOM should be updated indeed.
MOS 4024 is the right part?
That looks OK - has the correct voltage specs.
Thank you pichenettes for correcting the BOM.
I wasn’t shure where I ordered and which one I used for my Anushri, so I just checked it:
In my Anushri a 74HC4024 is working without any problem at 10V! The question is, how long? The absolute maximum rating according to the data sheet is 7V.
Mine didn’t seem to last long … (it was a new one from Reichelt).