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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
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Posted: Tue Sep 11, 2012 2:33 am Post subject:
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ah been looking into Dave's idea
using LM3914 to CD4532 and CD4051 he had the answer all along it seems
it would prevent a double output from ever occuring thanks Dave
only thing missing is NOT gates on the LM3914 outputs to drive the CD4532 inputs and we can also have LED indicators running directly from the LM3914 as well
So for an 8 way CV addressable switch seemingly it can be done with
only 3 chips 8 x 2n3904 and a hand full of resistors and caps and 8 LED's
although for a stand alone module i would also add a sample and hold to the incoming CV before the LM3914 to provide a clocking/ timing ability
the YASH circuit comes to mind
it could also be done from the CD4532 enable in pin but i think the sample and hold would be preferable as it effectively prevents output changes during the clock pulse on time.
would make an excellent module by itself i think and well worth the effort to prototype, what do you think matthias ? _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
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Posted: Tue Sep 11, 2012 6:34 am Post subject:
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yep. dave, you have become a CMOS guru, my friend! _________________
cheers,
matthias
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Big Boss at fonitronik
Tech Buddy at Random*Source |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
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Posted: Tue Sep 11, 2012 6:36 am Post subject:
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@diablojoy: would make a nice module indeed. _________________
cheers,
matthias
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Big Boss at fonitronik
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
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Posted: Tue Sep 11, 2012 4:03 pm Post subject:
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hmm one slightly annoying limitation
the CD4051 will switch bipolar signals but is limited to around +/-7.5 volts
in that case the chip must be supplied +/- 7.5 volts on the VDD and VEE pins respectively but in that case it will not be able to switch a +10v
signal such as a gate or reset . If VDD is supplied with +15v and VEE is at ground then gate , reset or clock signals could be switched, which is fine for the original topic but you can then no longer switch bipolar signals
If to be used for a CV addressable switch module this is quite limiting indeed
To get around this so far my only thought is to use the CD4051 I/O's to switch a pair of DG412 chips instead of doing the signal switching directly.
but it does add some more complication to the circuit
Anyone have another idea ? _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Wed Sep 12, 2012 12:06 am Post subject:
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diablojoy wrote: | hmm one slightly annoying limitation
the CD4051 will switch bipolar signals but is limited to around +/-7.5 volts
in that case the chip must be supplied +/- 7.5 volts on the VDD and VEE pins respectively but in that case it will not be able to switch a +10v
signal such as a gate or reset . If VDD is supplied with +15v and VEE is at ground then gate , reset or clock signals could be switched, which is fine for the original topic but you can then no longer switch bipolar signals
If to be used for a CV addressable switch module this is quite limiting indeed
To get around this so far my only thought is to use the CD4051 I/O's to switch a pair of DG412 chips instead of doing the signal switching directly.
but it does add some more complication to the circuit
Anyone have another idea ? |
one could just use diodes for protection/limitation. who needs 10V gates anyways? _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
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Posted: Wed Sep 12, 2012 1:22 am Post subject:
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Quote: | one could just use diodes for protection/limitation. who needs 10V gates anyways? |
Need perhaps not however i have gear that puts out 10 volt clock and gate signals [M2C as an example] and modules that happily accept that as an input as i believe many others do as well
limiting to 7.5 volt signals may be acceptable for 99% of what is out there
but it is touch and go for triggering cmos powered at 15v with out front ending it first, I know you cover that with your designs matthias but that
may not always be the case with others.
with my previously mentioned matrix sequencer idea it isnt an issue at all the levels involved are known and can be accounted for quite
easily, only one would be bipolar and that is well within the 15 v peak to peak for the other 3 the CD4051 can just be powered from 15v with VEE tied to ground and it wont matter.
For a CV addressable switch where i dont know who is putting what into where however i thought to try and cover as many variables as possible
then again as you correctly say who needs 10 volt gates perhaps i am trying a little too hard at covering all the bases and being a little too paranoid about it
protection diodes do sound good and easy .
edit: hmm the data sheet just says 15 volt peak to peak but only shows an example for +/- 7.5 volt supply for bipolar use, makes me wonder if a CD4051 will work with a offset supply with VDD at +10v and VEE at -5v but would VSS then still be at 0v - GND ? _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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Dave Kendall
Joined: May 26, 2007 Posts: 421 Location: England
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
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Posted: Wed Sep 12, 2012 12:21 pm Post subject:
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cheers, dave! that's a good find! and the price is okay for some DIY: about 3.50 EUR here at rs-components. _________________
cheers,
matthias
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
Audio files: 11
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Posted: Wed Sep 12, 2012 2:23 pm Post subject:
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Quote: | Simplest way might be with a DG408 - it's a 44V(!) version of the 4051. |
Damn Dave you really are good No make that brilliant !
will have a look over the datasheet tonight thanks again.
edit : must be my birthday [ 666 ] _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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JingleJoe
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
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Posted: Thu Sep 13, 2012 9:11 am Post subject:
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diablojoy wrote: |
edit : must be my birthday [ 666 ] |
While I was out walking just before I saw a bus with the number "666"
As for that high voltage multiplexor, read closely, I think it says somewhere that it's ground can only be 24 V below V+. _________________ As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"
Green Dungeon Alchemist Laboratories |
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
Audio files: 11
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Posted: Thu Sep 13, 2012 3:21 pm Post subject:
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Quote: | As for that high voltage multiplexor, read closely, I think it says somewhere that it's ground can only be 24 V below V+. |
Hi JingleJoe
Its referenced from V- and is a max value only
with +/-15 volt supply it will all be fine
in that case GND will be at 0V
If I am understanding it correctly it is the maximum to be taken into consideration perhaps mostly for in the case of when a single positive supply is used where the V- pin is tied to GND for switching larger positive voltage only signals , in that case the GND pin becomes a virtual GND and will need to be at a + voltage decided by the value supplied to the V+ pin.
So if V+ is at +44V and V- is at 0V then GND pin will need to be at a minimum of +20V but also no more than +25V . The half way point would be what is being aimed at here.
edit : To put it another way, once the positive supply to V+ pin exceeds +24V the GND pin must be supplied a positive voltage to keep up.
So the chip does cover a lot of possible ranges.
666 no longer. oh well _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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delayed
Joined: Jun 24, 2008 Posts: 130 Location: TN
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Posted: Fri Sep 14, 2012 12:39 am Post subject:
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just subing to this to see how it turns out |
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JingleJoe
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
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Posted: Fri Sep 14, 2012 1:41 am Post subject:
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diablojoy wrote: |
If I am understanding it correctly it is the maximum to be taken into consideration perhaps mostly for in the case of when a single positive supply is used where the V- pin is tied to GND for switching larger positive voltage only signals , in that case the GND pin becomes a virtual GND and will need to be at a + voltage decided by the value supplied to the V+ pin.
So if V+ is at +44V and V- is at 0V then GND pin will need to be at a minimum of +20V but also no more than +25V . The half way point would be what is being aimed at here.
edit : To put it another way, once the positive supply to V+ pin exceeds +24V the GND pin must be supplied a positive voltage to keep up.
So the chip does cover a lot of possible ranges.
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Yes
diablojoy wrote: |
666 no longer. oh well |
All things are fleeting. _________________ As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"
Green Dungeon Alchemist Laboratories |
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
Audio files: 11
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Posted: Fri Sep 14, 2012 3:49 am Post subject:
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Delayed wrote
Quote: | just subing to this to see how it turns out |
I expect at least a couple of projects could come from this so i am reasonably confident it will turn out very well,
I would be surprised if matthias or dave did not come up with something from it quite soon, certainly quicker than i am likely to anyway.
However my final goal is for a bigger project which i have had in mind for several years so i will be pursuing this for as long as it takes.
first thing is to come up with a working prototype 8 way CV controlled switch
I have now made a start at least, most of the basic schematic is sorted
and I ordered the required chips as of yesterday, its now down to details ....of course the devil is in the details and i am not so fast . I will start a new topic when i have something or perhaps Matthias or dave will, any way it goes i feel good _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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