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 Forum index » DIY Hardware and Software » YuSynth
Clock divider Led resistors
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Satindas



Joined: Mar 26, 2011
Posts: 39
Location: uk

PostPosted: Thu Feb 09, 2012 3:15 pm    Post subject: Clock divider Led resistors Reply with quote  Mark this post and the followings unread

Hi Yves,
Could you tell me which resistors to change for the Clock Divider LED's.
My blue led is soooo bright. Cool

Many thanks
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ungleichklang



Joined: Dec 03, 2011
Posts: 82
Location: East-Belgium

PostPosted: Fri Feb 10, 2012 1:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

I haven't build it, but as far as I can see from the shematics,
the devider has 3 LEDs
they are connected to (R12, R24, R36) 220R resistors.
I think (I am pretty shure) you have to change those Smile

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Satindas



Joined: Mar 26, 2011
Posts: 39
Location: uk

PostPosted: Fri Feb 10, 2012 3:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

ungleichklang wrote:
I haven't build it, but as far as I can see from the shematics,
the devider has 3 LEDs
they are connected to (R12, R24, R36) 220R resistors.
I think (I am pretty shure) you have to change those Smile


Thanks ungleichklang. I was suspecting those resistors but not sure if it could also be down to 13, 25 & 37. Changing either of these two groups would seem to alter the potential divider across the output..
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Fri Feb 10, 2012 8:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
I was suspecting those resistors but not sure if it could also be down to 13, 25 & 37. Changing either of these two groups would seem to alter the potential divider across the output..


Yes- you're exactly right.

Since you're trying to use those #$S# blue LEDs, it's not unusual to have to use a 10K resistor with them. That will mess things up in this case.

Here's what I think you could try (do it on one of the circuits first to see if this works)

1) Connect the cathode of the blue LED to a 10K resistor to ground.
2) Connect the top side of R12 directly to the emitter of the transistor (pin 7 on the schematic). You should probably increase the size of that resistor until the output level is at 10V (if you have the zener diode in place, this won't matter).

I think that should do the trick. Alternately you could change R12 to 10K, and do some math to work out a new value for R13 that would restore the output level to 10V.

OR you could just use regular LEDs Laughing

Gary
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Satindas



Joined: Mar 26, 2011
Posts: 39
Location: uk

PostPosted: Sat Feb 11, 2012 1:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks Gary. That all makes sense. I think I'll do a quick simulation based on your suggestions (my electronics math is rubbish). Why did I choose blue? For quicker id. I have a different colour led for each output; red, yellow and bue. I'd settle for red,yellow and green but I'm red/green colour blind. colors
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Satindas



Joined: Mar 26, 2011
Posts: 39
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PostPosted: Sat Feb 11, 2012 2:11 am    Post subject: Reply with quote  Mark this post and the followings unread

so this is how it looks...

Replace R36 with 470R connected to emitter of Q9 (maintains 10V at output)
Blue led to ground via 3K3 resistor ( 3.54 mA through led = half of original current)

Doing it the other way; subbing a 1K for R36 and 3K for R37 gives 9.48V out and 3.16mA through the led. (good enough for jazz!)

So...Gary I like your idea of a separate ground connection for the led. At least that way if the led fails I still have a clock output.
thanks Gary... Now I can remove my shades
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Sat Feb 11, 2012 7:01 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm glad I could help.

BTW - I have one of those modules sitting on my table right now. Still waiting to get built!

I like the idea of using different LED colors for each channel. I think I might do that. Thanks for the idea!


Gary
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wackelpeter



Joined: May 05, 2013
Posts: 61
Location: germany
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PostPosted: Tue Oct 28, 2014 11:42 am    Post subject: Reply with quote  Mark this post and the followings unread

hi all,
i have just built that module as double divider on stripboard and it works, but i have a problem that it seems to suck too much current when the LED is on... first noticed that when i got my 3rd and 4th 555vco working with it on the same case and power supply... i noticed slightly variations in pitch when the LED was on and so measured the Output voltage which Drops a bit and the current... the voltage goes down ca.200mV and the current of all my modules in that case is 123 to 124mA and when i turn in a Trigger in that module and raise the Speed so my multimeter can caught that current it goes up to 129-130mA...

my power supply is a traco 15215 with 0,5A Output... have it in use in 2 other cases without any problems...
what can i do to erase These voltage Drops? have already used different resistors 3,3k for r13 and 1,5k for R12... the voltage Drops went slightly lower but are still audible in my vco... red LED is slightly better than green...
should i go for low current LED's or are there any other things to tweak it a bit better?
also have used 2 different 4017 Chips hfe and CD but without any changes...

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jksuperstar



Joined: Aug 20, 2004
Posts: 2491
Location: Denver
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PostPosted: Tue Oct 28, 2014 1:23 pm    Post subject: Reply with quote  Mark this post and the followings unread

What kind of 555?

I'm digging through my mental archives (which takes some time these days), but I think one of the types of 555 timer (Bipolar, CMOS) could basically short power to ground depending on the circuit implementation.

At least it's a starting point to look into.
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wackelpeter



Joined: May 05, 2013
Posts: 61
Location: germany
Audio files: 7

PostPosted: Tue Oct 28, 2014 2:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

no timers included in this circuit...

here's the schematic:
http://yusynth.net/Modular/Commun/DIVIDER/ClockDivider-sch.gif

the 4017 chip itself i think isn't causing that Problems because as Long as the buffer isn't included (LED traces left open) no voltage drops occured...
it's somewhere in the buffer stage i guess...

btw. don't know exactly if these voltage Drops also appear with other psu's or if they where better buffered... i think i just have to minimize the current drawn by the led somehow... tomorrow i'll try to change the resistors r12 & r13 with some higher values... simply higher resistor value less current...

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prgdeltablues



Joined: Sep 25, 2006
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PostPosted: Wed Oct 29, 2014 6:21 am    Post subject: Reply with quote  Mark this post and the followings unread

I've built that module - with two of Fonik's clock dividers too, on one board, no problems with the LED such as you describe. The type of LED shouldn't make much difference. As designed, the LED is drawing a bit under 10mA (15V less LED voltage drop, across R12+R13. I use low current LED's aiming for about 2 mA draw or less - from memory, I probably used 4k7 or 10k for R13. I do use a separate 'dirty' ground for LEDs and digital chips from the 'clean' analog ground though.

Have you got enough decoupling - you could try increasing C1 and C2 to say 22u, and ensure you've decoupled the 4017s too. Otherwise it suggests a near short to ground somewhere around the LED/buffer. Does the effect occur for all of the 4017 circuits - or just one - try taking all the 4017s out and replace them one at a time - if it is a short, it would be unlikely it would be present on all three sub-circuits.

Peter
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wackelpeter



Joined: May 05, 2013
Posts: 61
Location: germany
Audio files: 7

PostPosted: Wed Oct 29, 2014 12:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi,

it's getting a bit curious...

well what i've done so far changed both decoupling caps (General and tranny) to 22uF
chip is already decoupled with an 100nf as Close as possible between + and gnd...
changed r13 to 30k and r12 to 1k5 (i have an 5V Z-Diode at the Output, but it's the same w/o)
also put collector of buffering tranny with 1k to + for LED...
best result gave a blue LED...
what i dsicovered now and haven't noticed earlier is that it takes some time before this pitch shifting appear... first i plug in the power nothing happens, pitch is constant, led and Trigger Signal work perfect and after a while (sometimes 10 secs or the other time after an Minute or so, the pitch begin to shift... Looks more like an problrm with the supply i guess, correct???
took another 47uF between - gnd + trying to stabilize that a bit further.. but same again...

tested that again with the led wires left open, means nothing connected after the Emitter of the tranny.. and voila same again... hasn't to do with the led as expected... or at least the buffer is just a small part of the whole Problem...
btw. it's the same on both dividers... built only 2 of them due to the lack of space on that Piece of stripboard...
what Kind of Chips for the 4017 are best recommended... i have tried HCF4017BE and Cd4017BE

when i have some more time i'll Change the psu with one out of my other cases... to check that possibility of a whacky psu...

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wackelpeter



Joined: May 05, 2013
Posts: 61
Location: germany
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PostPosted: Thu Oct 30, 2014 12:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

ok Folks, thanks for all the recommendations and tipps but you have better asked me first if i triple or quadruple checked my wiring and layout... Laughing

hmm... well was at least to blind and stupid to see that i forgot to put pin 13 on ground... Rolling Eyes
now it works wonderfull and no pitch shifting at all...


edit: Erratum... the second one didn't work as well as the first one... seems as one of my attempts was part of the solution... because the 2nd one is now as per schematic.... seems as i have to solder a bit...

R12 1K5 and R13 30K and the C of the buffering Transistor through a 1K5 resistor to Vled and voila perfect...

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