I though that this might be of some use for adapting a LM13700 to an existing 3080 project.
(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/finished%20side%20I.jpg)
Here's the PDF with info and PCB print:
https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/LM13700%20-%20CA3080%20adapter%20board.pdf (https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/LM13700%20-%20CA3080%20adapter%20board.pdf)
Nice. Now we just need to make an adapter board for all of the fake LM13700 chips from china. ;D
Good work!
You know what's funny....
Before I started working on this I wanted to make sure that there wasn't one available on the net....so I searched around....
Do you know what I found? An adapter board to combine two 3080s to make a 13700! :icon_eek:
Nice work Armdnrdy! really nice pdf !
Haha what 2 3080 adapter board! crazyness!
I was lookn at it and wasnt sure about the resistors. Pull down resistors from power and input ? That works good for most applications ?
I been trying to figure out how to use the buffers on the 13700 , found a few projects that used them but they where for synth modules I think. Got any ideas for implementing the buffers ?
Thanks Jim.
The two resistors make a voltage divider on the non inverting input. The inverting input is tied to the output.
I found a post on Texas Instrument's site where the question was asked, "How to deal with the un-used cell for LM13700?"
The answer from a T.I. engineer was: set up the unused portion as a unity gain follower with it's input at half supply.
I figured for the price of two 10K resistors, (next to nothing) and a couple millimeters of board space...it can't hurt.
As far as using the buffers...I don't really see the buffers used in the project files that I have. The designer of the LM13600/700 stated in an article that they were added because 3080 designs generally use buffers.
I am not aware of such designs.
The buffers collectors are tied to V+......so that limits the use as a local general purpose NPN.
Hopefully R.G. will pop in! :icon_wink:
Here's a good read by Ray Marston. Article on 3080s and 13700s.
Understanding and using OTA Op Amp ICs:
http://www.nutsvolts.com/uploads/magazine_downloads/11/April%202003%20Ray%20Marston%20-%20Understanding%20and%20Using%20OTA%20Op-Amps.pdf
Quote from: Mustachio on December 08, 2013, 09:34:05 PM
Haha what 2 3080 adapter board! crazyness!
I actually need one of those ...
Quote from: midwayfair on December 08, 2013, 11:32:40 PM
Quote from: Mustachio on December 08, 2013, 09:34:05 PM
Haha what 2 3080 adapter board! crazyness!
I actually need one of those ...
Blasphemy! Your in luck I believe thats called an LM13700 :icon_biggrin:
Nice link armdnrdy! I looked up the next edition with the lm13700 info.
http://www.nutsvolts.com/uploads/magazine_downloads/11/May%202003%20Ray%20Marston%20-%20Understanding%20And%20Using%20OTA%20OP-Amps.pdf
Check out the bottom vcf's looks like their using the buffers. I gotta try bread boarding something up with that when I get time I love vcf's!
:::Edit:::
Oh yeah when I first read the url I read it as Nuts And Volts and lol'd! that would be a great site but nutsvolts is great too! :icon_lol:
I have a combined copy saved in my OTA folder.
I thought the link that I posted had both articles. ???
Good you found it! Great articles!
Quote from: Mustachio on December 09, 2013, 12:05:39 AM
Quote from: midwayfair on December 08, 2013, 11:32:40 PM
Quote from: Mustachio on December 08, 2013, 09:34:05 PM
Haha what 2 3080 adapter board! crazyness!
I actually need one of those ...
Blasphemy! Your in luck I believe thats called an LM13700 :icon_biggrin:
Madbean's Sharkfin (FSH-1) uses two 3080s instead of an LM13700. Brian said it was because it fit better on the layout, but the two 3080s are right in line with each other, so I'm a little confused by that reasoning. I bought the 3080s, but every time I look at them, I think "eewwwww."
Quote from: midwayfair on December 09, 2013, 09:53:53 AM
Madbean's Sharkfin (FSH-1) uses two 3080s instead of an LM13700. Brian said it was because it fit better on the layout, but the two 3080s are right in line with each other, so I'm a little confused by that reasoning.
It has to do with where the pins are on the chip for a given function. I prefer two dual opamps to one quad opamp for the same reason. The signal flow on the PCB layout can be improved. I suspect that Brian has read my "PCB Layout for Musical Effects", where the topic is addressed. I've posted the concept here, too.
That, my friend, is very useful. Thanks!
Buffers are actually separated from OTAs, you can use them for anything you need:
Vref buffering, extra filtering stage, OTA's Vc etc..
You can make 4 LP/HP filters out of a 13700 using buffers, or double buffer a dynacomp...
Quote from: R.G. on December 09, 2013, 10:06:03 AM
Quote from: midwayfair on December 09, 2013, 09:53:53 AM
Madbean's Sharkfin (FSH-1) uses two 3080s instead of an LM13700. Brian said it was because it fit better on the layout, but the two 3080s are right in line with each other, so I'm a little confused by that reasoning.
It has to do with where the pins are on the chip for a given function. I prefer two dual opamps to one quad opamp for the same reason.
So ... you're saying we can't win? Noisy 3080s or awkward 13700 signal flows? :(
;)
BTW, RG, the smallbear link for your book on your site seems to be broken. Maybe the link changed. http://www.smallbearelec.com/servlet/Detail?no=679
What about the SSM 2164 quad VCA? Not OTA I know, but only Ashdown pedals seem to use them.
Maybe Gilbert cell.
It is possible to make an OTA with monolithic pairs of transistors. I think I posted that here some years ago. The tracking and such won't be as good, but you *can* make them.
The input diffamp is what's critical for matching, and everything else needs matched only locally to the pair, as the others are all current mirrors. The mismatch from mirror to mirror is much less important than mismatch within the pair, and matched pairs are what you can get. There are no resistors or caps in an OTA - only active devices. It's all silicon.
Quote from: R.G. on December 09, 2013, 05:35:14 PM
The input diffamp is what's critical for matching, and everything else needs matched only locally to the pair, as the others are all current mirrors. The mismatch from mirror to mirror is much less important than mismatch within the pair, and matched pairs are what you can get. There are no resistors or caps in an OTA - only active devices. It's all silicon.
Is it essential that the Darlington pair in the emitter follower buffer of both the 13700 and 3094 be matched?......or....not so much?
Matching doesn't mean all that much for Darlington pairs. In fact, it's usually counterproductive. The first transistor in the cascade (as opposed to pair) is guaranteed to be working at a collector current that's 1/HFE of the second. So you want a first device that's optimized for gain, bandwidth, linearity, etc. at a much lower current. This is one reason that monolithic darlingtons are generally better performing than discrete - a lot of thought went into optimizing them for the situation.
So not matched - but selected for a particular performance. Got it. Thank you
If your tired of using FET for MXR noisegate I recommend this http://hammer.ampage.org/files/Expander.gif (http://hammer.ampage.org/files/Expander.gif)
I got this way back years on Mark's website and I built this using separate TL061 and 3080 and its verified. I just copied the PCB design and scale to fit my case.
Although the PCB is not for LM3700 but I think it can be done. If only someone can redesign the PCB into LM3700 :)
(http://i186.photobucket.com/albums/x139/rogeryu_ph/ExpanerandNS2noisegate.jpg)
Quote from: midwayfair on December 09, 2013, 09:53:53 AM
Quote from: Mustachio on December 09, 2013, 12:05:39 AM
Quote from: midwayfair on December 08, 2013, 11:32:40 PM
Quote from: Mustachio on December 08, 2013, 09:34:05 PM
Haha what 2 3080 adapter board! crazyness!
I actually need one of those ...
Blasphemy! Your in luck I believe thats called an LM13700 :icon_biggrin:
Madbean's Sharkfin (FSH-1) uses two 3080s instead of an LM13700. Brian said it was because it fit better on the layout, but the two 3080s are right in line with each other, so I'm a little confused by that reasoning. I bought the 3080s, but every time I look at them, I think "eewwwww."
Oh nice Jon! I built the FSH from tonepad a few years ago. I hadn't seen madbeans version but I gotta say everything that comes from madbean is top notch! Its a very cool pedal but I did have a time getting the sample hold part how I liked it. Had to play with a bunch of different j201s . In the long run it was great but I had almost wished I built it with less controls like the original. Switching modes had me changing most the controls to get it how I liked the sound , so having 2 foot switches was pointless on mine . I would have been better off wiring the S/H mode on a toggle like the filter direction mode.
Are you gonna do a video when you build yours ? Id like to hear it because I wasn't fully happy with mine and started cannibalizing it for parts. The filter section on it was really nice though!
That expander/gate from Mark looks really neat! Instead of redesigning for the lm13700 should just make the adapter board armdnrdy made for this thread. I've been needing a noise gate maybe ill give it a try soon.
Thanks again for the Adapter board armdnrdy I think it will help a lot of people out !
I just finished up the files for a LM13700 - CA3094 adapter board. This first version is for use in a circuit that leaves pin one unconnected (frequency compensation) and ties pin 8 (source /drive output) to V+.
I've seen a lot of circuits that use this configuration.
The second version is a bit more difficult. It includes the use of both pin 1 and 8.
It will include a discrete split darlington pair with a 2K resistor on the first transistor's collector and a 47K base resistor on the second transistor.
I still have to work out some of the details for the second version. Every step I take....I'm forced to learn something! :icon_wink:
Looking through available data on darlington pair calculations, it looks like to properly calculate the specs of any given pair...you would need the information from the individual application.
The 3094 spec sheet lists the hFE at min. 16,000 / max. 100,000 for the given test conditions. That's quite a swing!
So..if you were to use four 3094s in the issue "J" small stone, you would have to "match" the buffers hFE to guarantee similar performance in each phase stage. (In theory of course)
Since I don't think that would have been a wise production decision, EHX would have installed available 3094s to achieve the desired effect without "matching".
With that being said, I'm looking to devise the easiest way possible for users to construct a "work alike" 3094 adapter board using a 13700 OTA, and a split darlington pair.
My thought is to use a known low hFE transistor for the first Q of the cascade, and a known high hFE transistor for the second.
Something like a PN2222 and a MPSA18.
I don't have any 3094s for testing purposes...and at $5.00+ for questionable authenticity.....I think it's going to stay that way!
Am I on the right track or way off the trail?
I whipped up this schematic showing the common pins of the 3094 and the potential work around.
(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/13700-3094%20II.jpg)
Quote from: DIMstompboxes on December 09, 2013, 06:06:26 PM
If your tired of using FET for MXR noisegate I recommend this http://hammer.ampage.org/files/Expander.gif (http://hammer.ampage.org/files/Expander.gif)
I got this way back years on Mark's website and I built this using separate TL061 and 3080 and its verified. I just copied the PCB design and scale to fit my case.
Although the PCB is not for LM3700 but I think it can be done. If only someone can redesign the PCB into LM3700 :)
(http://i186.photobucket.com/albums/x139/rogeryu_ph/ExpanerandNS2noisegate.jpg)
I wonder If anyone is intrested in making this gate to suit the lm13700 please
It looks intresting to a bunch of us who are striving to rework the mxr noise gate. Please pm me if you think you can help.
thanks
Sorry for threadjacking.
Rich,
I'm not sure I understand your request.
If this project is reworked for a 13700, how is that going to help "rework" the MXR noise gate which is JFET based?
True It might not help with reworking the mxr gate.
We are trying all differant ideas to get a Gate that works without defunkt parts (2n5952)
and is reasonable to build. theres lots of other considerations but for now an lm13700 is one of the considerations so it just might help Larry .
Gotcha!
On your build, I see two controls...one for the sensitivity. What is the other one? In the schematic I see a switch for expander/normal. Did you put that on a rotary type switch or use a pot to make it adjustable?
It was DIMstompboxs post i qouted. sorry cant help
Here's your noise gate with a LM13700.
I'll post the project tomorrow. (it's 1:00am right now....time to sleep!)
(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Noise%20Gate.jpg)
Omg
Thanks dude
Thats excellant I'll give it a try
Rich
Quote from: armdnrdy on December 12, 2013, 03:52:49 AM
Here's your noise gate with a LM13700.
I'll post the project tomorrow. (it's 1:00am right now....time to sleep!)
(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Noise%20Gate.jpg)
And???? what happend with this???? yeahhhhhhh please don´t let it DIE!!!!!!!!!!!!!!
Quote from: GodSaveMetal on September 05, 2014, 10:24:47 PM
And???? what happend with this???? yeahhhhhhh please don´t let it DIE!!!!!!!!!!!!!!
Search function..."noise gate"
http://www.diystompboxes.com/smfforum/index.php?topic=105397.0
What about using the CA3280 ? :)
Quote from: chicago_mike on September 06, 2014, 06:19:04 PM
What about using the CA3280 ? :)
A 3280 would work just fine in this circuit. Due to the different pinout..you would have to make a daughter board or rework the routing. The 3280 has been discontinued for years. That's why I used the easily obtained 13700 for a replacement for the 3080. If you have a drawer of 3280s and some time on your hands...go for it!
Hi Larry from our temporary environment of hot sun, palm trees, fresh air & fun (!!) somebody once posted a rework of the EH Smallstone using 3280s, possibly back on the old forum days in the 90s. Mark may remember.
Quote from: StephenGiles on September 07, 2014, 03:05:52 AM
Hi Larry from our temporary environment of hot sun, palm trees, fresh air & fun (!!)
Hey Stephen,
From your decription...it sounds like you are visiting my neck of the woods....Southern California. :icon_wink: