Remaking a one-off custom job.. help...

[quadwould]

A well know Dub producer/mixer friend has this bit of kit. it is a one-off custom job, hand wiring and breadboard. he wants me to reverse engineer it and build another one for him. He would have going to the original designer, but unfortunately he i no longer with us.

Here are the obsolete parts..
First of a VCA of SSM 2013

second, a waveforme gen, RS 305 844 aka ICL8038CCPD
Below is what you get at the RS website.

" Waveform Generator,ICL8038CC
* RS Stock no. 305-844
* Manufact. part no. ICL8038CCPD
Discontinued product"

I'll pot pictures at some time soon. its fairly simple, yet crazy since it was done on project board.


so, anyone know where i can get these?

 

[gyraf]

SSM2013 qualifies as a "vintage" synth-ic, probably available for good money at that community.

8038 was a widely used function generator, and should still be possible to find at your local pusher.

Don't use any of these if you plan on building more than a few units.

Jakob E.

 

[quadwould]

Hi Jakob,


yeah thats the problem. Depending on if he is really satisfied with the first one i do, he might want to do a small production run (maybe 30 max .. or i hope no more.. too much work)

I am soon (once i upgrade my Mac to Tiger) to be entering the schematic and creating a PCB for this.

If there were replacement chips out there that were pin-for-pin that woud be really great. otherwise i will have to rework the schematic and pcb a little. If there are not pin for pin replacements out there, are there any ICs that sound the same (or damn near) with the same functions?

 

[gyraf]

To consider production, even small series - based on those chips - would probably be an error. Think of future repairs also!

My suggestion is: Build a proto with originals and an adaptation using moderns - and compare these (blind test!!!). Get the modernized at least as-good-as original, and serialise that in stead...

Jakob E.

 

[chrissugar]

[quote author="quadwould"]A well know Dub producer/mixer friend has this bit of kit. it is a one-off custom job, hand wiring and breadboard.[/quote]

Is it a Dub siren?

chrissugar

 

[quadwould]

Heh...nope Chrissugar, not a dub siren, but esentially has the same usage. Its a frequency generator, (usually used at very low frequencies) it can be hand triggered (which this guy like to do,) or it can be triggered from an input- like a sidechain. and has a couple of other whistley bells as well.



good idea Jakob. should have thought of that myself.

I will be posting pics soon of the original. It'll be a long day tracing all of the wiring to draw up a schemat.


Any Suggestions for replacement VCA and Function Gen?

 

[SSLtech]

Quad,

I think I have some SSM2012's... how different are they?

Keith

 

[ruairioflaherty]

Quadwould,

I've got some SSM2014. I mean they got to be better than Keith's 2012 right? :green:

I've got a datasheet I can email but I just found it on google. Let me know if they might be of use,

cheers,
Ruairi

 

[quadwould]

Hey Ruairi, thanks for the offer, however it would be of no use to me. actually the 2014 is quite a bit different from the 2013.

Keith, the 2012 is pretty close to the 2013, indeed almost the same. I think i will try the safer (though harder) route of trying to find a replacement chip for the SSM2013, one that is still in production.

and also try to find a replacement fo the ICL8038CCPD as well.

I've found a coouple 2013's online at like 15USD or so in price. i'll pick up a few of those, and hope i can get a few old 8038s as well.

The course now though it to find the closest csounding and functioning chips to the ssm2013 and the ICL8038CCPD .

joy.. what a task.

anyone??

 

[JohnRoberts]

I don't know that anybody makes a modern equivalent of the 8038. I recall using it in a console line up osc decades ago. It was not very low distortion but adequate for crude tasks with minimal footprint.

If you must roll your own there are about a zillion ways to make a sine wave. The 8038 used a technique known as a "diode break" amplifier to convert a straight line triangle wave to the curved sine wave shape (actually a series of straight line approximations). This approach while not very low distortion did have the nice characteristic of good amplitude stability and instant start up. You can get a hint about how to roll your own from the spec sheet. A bunch of transistors that start conducting at progressively higher thresholds. For comparison a sine wave slope is approx 1.5x the similar frequency/amplitude triangle wave slope when passing through 0V, while approaching zero slope at max and min extremes.

If you use a different sine wave approach you may want to keep it running and gate it on/off to get the effective instant on and amplitude stability of 8038.

JR

 

[quadwould]

Hey John,

yeah the spec sheet is a max of transistors. far to complex to try doing it discretely and be cost effectife and efficient with pcb space.

I actually need to get sine, tri, square, and noise from this thing.

found one person selling an 8038 for 30 quid.. HA! still looking

 

[JohnRoberts]

The square and triangle wave can be made simply with two opamps and a few parts. The diode break portion might be simplified somewhat, and made more symmetrical by putting both polarities inside a full wave bridge, inside a feedback loop.. but agreed not trivial or compact.

JR

 

[jdbakker]

[quote author="quadwould"]found one person selling an 8038 for 30 quid.. HA! still looking[/quote]
I believe this:

http://www.jdr.com/interact/item.asp?itemno=ICL8038CCPD

is a pin-compatible part (and even in stock), but don't take my word for it.

JD 'YMMV' B.
[not checked whether they ship outside the US]

 

[jdbakker]

...and this guy:

http://cgi.ebay.com/XR8038CP-Precision-Waveform-Generator-XR-8038CP-14-DIP_W0QQitemZ270111054292

has a dozen XR8038s.

Even so, at this point you're designing an unmaintainable piece of equipment. How much worse would a simple microcontroller with an n-bit R2R DAC be at generating the waves you need ?

JD 'dev time invested now vs parts sourcing headaches later on' B.

EDIT: shorten URL

 

[gyraf]

8038 is still quite easy to find at your local shop, e.g.:

http://www.el-supply.dk/?M=Searchmode&showResults=1&Action=Search&Archive=False&Order=Desc&Searchstring=8038&NewsPublisher=True&Url=%2F%3FId%3D

(danish shop, will ship internationally if you call and ask nicely)

Jakob E.

 

[jdbakker]

And odds are that all NOS 8038s are non-RoHS. You may not care, but that means that it won't get easier to get a hold of them in the future, with many distributors effectively tossing all leaded parts.

JDB.

 

[quadwould]

right... so bit of an update..

the 8038 is a rather useful and good chip and so i am sticking with it for the design. i will order 2-3 times as many as i need and that shoul sort out any repairs or additional few requests for units.

now the real bain of my life is that poxy SSM 2013


is there any chip out there, does not need to be (nor likely is) pin for pin, that sounds/acts the same as the 2013??? or maybe cleaner?


i have schemat/pcb software that i will run in Virtual PC. (ugh) and will soon have the schemat posted... will be needing help with some mystery parts.

 

[SonsOfThunder]

Hmm...I duhnno about that extra opamp/diff pair hanging on that part but have you considered the SSM2164 for a VCA? Its 4 pcs in one pkg, they can be combined in parallel for a noise advantage if you need it. They are quite good devices...

HTH!
Charlie

 

[adamasd]

The 2164 is probably your best bet for current production if you want a single chip. Assuming the design does not use the mute function of the 2013 in anyway.

If it was me I would just use a pair of 13600s to make a tri/square VCO and a VCA. Especially if there was a chance it would go into even limited production. Its just a handful of passive and 4 transistors, so nothing to complex. Sure its not the same, but almost as simple.

 

[quadwould]

"The 2164 is probably your best bet for current production if you want a single chip. Assuming the design does not use the mute function of the 2013 in anyway."

It looks like i do need the Mute function.. Havent yet input everything into a Schemat program, but have traces the existing circuit and the "typical connection" as found in the pdf online is used.... meaning mute is used somehow....

have to investigate more but...


any suggestions... Any 14 pin VC Audio As out there with a mute in them?