LM13700 End of Life

Yeah - saw this (as well as Monty Python skits) fly by on the synth-DIY list.
I have to agree with whoever it was on there saying “put the SOIC ones on a breakout board”.

Cheers

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I’ll never understand why companies don’t offer a suggestion for a replacement part when one is planned for obsolescence…

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Yeah, @moritzklein mentioned it in his stream. I presume folks will just use some to dip adapters if they need to use a 13700. Quick, start stockpiling now! :grinning:

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yeah thats where i saw it.

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putting or finding breadboarded soic lm13700 would be a find or a deal to buy from. Alot of older chips are doing that as we speak.

As I understand it, the LM13700 was designed as basically two RCA (later Intersil) CA3080s in a single package. The latter chip went out of production around 2000, I think? But now Rochester Electronics produces a through hole CA3080, and Alfa makes the AS3080. Neither’s cheap (the Alfa is $4.99 from SynthCube, the Rochester is $3.89 with minimum quantity 65 at DigiKey) but they’re available. Presumably it’d be relatively quick and easy for both companies, if they chose, to make versions of the LM13700N. Assuming there are no legal impediments to doing so, I’d be surprised if Alfa at least isn’t working on that right now.

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There are some minor differences between the 3080 and the 13700, but Alfa already has a quad 13700 version so as you say, it’d be surprising if they don’t roll out an AS13700.

Rochester only packages existing wafers, though, so if they will be able to supply new ICs depends on TI.

EDIT: Turns out Rochester has some LM13700 stock, and at a nice price too, if you’re ok with their minimum order size :slight_smile:

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I checked a couple of Chinese distributors (LCSC, Chipsmall) and they have a preorder page for a DIP-16 “LM13700M” from a Chinese manufacturer (Gcore) that makes a bunch of other classics as well. No datasheet on the sites yet, www.gcore.com.cn gives me a 403, and LCSC has it categorized under “batteries,” but a bit more Googling brought up a Chinese-language datasheet in Google’s cache, and it’s definitely an OTA.

EDIT: To continue a bit further down this Chinese OTA rabbit hole, I found Gcore’s 1688 store: https://shop1473055479092.1688.com. No 13700 there (yet?).

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chipsmall.com says it’s not a battery. They illustrate it with an SOP-16 package but who knows.

Ok, I may have missed it before but there’s now an LM13700m in the the Gcore store’s index. The link is dead, though.

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Looks like Tayda just got new stock, they have 2339 of them available.

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Maybe we can get this guy to design us an LM13700 substitute

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Wow. Just noticed Tayda’s charging $3.99 for an LM13700N. About twice what they were charging a few months ago.

And $1.37 more than Mouser!

Strange times.

At least they have it. Digi-Key doesn’t.

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I haven’t tried this yet, but there is a way to make them from ic4007 CMOS ic’s.

https://wiki.analog.com/university/courses/alm1k/alm-lab-ota

I know it’s not compact and can’t say anything about performance, but it is already cheaper, and 4007s will probably not run out soon :slight_smile:

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Noted at Barton Musical Circuits:

Due to the DIP package LM13700 going out of production, new PCBs using the SMD version of the 13700 are available for the following projects:
BMC15. VCA MIX
BMC18. ANALOG DRUM
BMC23. DECAYING ANALOG NOISE
BMC25. FM DRUM
BMC53. 4QMP
A new version of BMC55. SK VCF will be available later this year.

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Hi! love your creations . Yeah is the LM13600 as good as the LM13700? I see you can buy a tube of 25 , for $19 at Synthcube. Just curious about your thoughts on that item, thanks.

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I went looking and found this SOIC to DIP breakout

which looks like it would work to put an SMD LM13700 in a board designed for the DIP package, at least if there’s a little space to the sides of the footprint. If something narrower is needed there’s this but it costs more.

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If you’re ready to do some small stakes gambling, the aptly named Fantasy Electronics on AliExpress has LM13700s at 5 for $2.12 plus shipping:

There’s no logo on the pictured chip and no claim it comes from TI or from any other manufacturer, so… don’t get your hopes too high up. Still, at least one customer seemed happy:

Real Chip!!! Finally, a real chip from AliExpress! I tested all 5 of them using the triangle/square wave VCO from the Texas Instruments datasheet (figure 33), and they worked perfectly. The calculated oscillator frequency matched the measured frequency exactly, so everything in the chip must be working ok. The only section this example circuit doesn’t test is the linearizing diodes, you just have to take a chance that those work too (if you even need them). Like everything on AliExpress, these are probably factory reject parts, so maybe they won’t always work in your application, but at least they worked in the test circuit. These parts are hard to find in the US, so go ahead and give this one a try.

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I was just looking at my tube of lm13700’s from that seller last night and thinking that they have all the hallmarks of being genuine and that I should really make some VCA’s and filters with them! I think I did test them when I got them over a year ago and they tested good.
For reference I am about 90% sure the tl072 and tl074’s from the same seller are fake (lm324’s or whatever dirt cheap Opamp) but I haven’t done the through zero or slew tests to confirm (they still go boing in a bridge-T circuit) And the NE555’s are most definitely not genuine, package quality is sub-par, but I was expecting that for the price, they are most likely inferior clones.

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A while ago I got shoddy 555s and just for a laugh I piggy backed 2 and got a result. This was for robots not synths.