Chips for deadend fx Hapalochlaena / Frostwave Blue Ringer clone

[soldersqueeze]

I'm in the market for a ring mod, and the Blue Ringer looks a pretty interesting option. Thing is, as with most fun projects these days there's always something obsolete and hard to find. According to the project docs I need 2x3080TH and 1xAD633.
In the UK I can get the Rochester produced CA3080AE chips from Thonk and the Analogue Devices produced AD633ANZ from Mouser. Neither are cheap options so I don't want to dump £25 on three chips if they're not suitable.
If anyone has the experience or knowledge to advise me I'd be hugely grateful.

[ElectricDruid]

Welcome soldersqueeze!

I've heard of the Green Ringer, and I've heard of the Blue Clipper, but I've never heard of the Blue Ringer! Have you got a schematic for what you'Re talking about?  2x3080s and 1x633 is a lot of chips for a ring mod - one of any of those would be enough, so this makes a big difference.

Thanks,
Tom

<edit> Never mind, I've found it:
https://drive.google.com/file/d/1Pt4Vf_lv8XeQZaSPm-R03rJ-zvnKOUGY/view

I'd say, yes, you need a CA3080 - either the Rochester originals, or an Alfa AS3080E clone (also not cheap, per OTA). And the AD633 was always expensive, but it's one of the best analog multiplier chips out there. So what you've chosen isn't the cheapest ring mod to build, but it should be good quality.

There are things I could criticise about the circuit. Why not use a LM13700 instead of two CA3080s? Would have been cheaper and probably easier/more compact too. But that's not really relevant here.

[soldersqueeze]

Welcome soldersqueeze!

The way you phrased that made me look at my post count, and it appears this is my first post since joining in 2013... I think I could be be in the running for lurkiest lurker on this board.
I have learned a lot from here though, so my lack of participation is not down to disinterest I assure you!
Thanks for taking the time to have a look and answering my question, it's very much appreciated, as is everything you've done for the DIY community, I'm a big fan of your work.
Maybe I'll manage another post before 2030 and bring my average post per year count up...
Thanks again.

[iainpunk]

one CA3060 seems to be used without varying bias current, so the gain should be static, so maybe you can re-design it to take a normal opamp there? (im not sure about this tho)

cheers

[PRR]

one CA3060 seems to be used without varying bias current, so the gain should be static, so maybe you can re-design it to take a normal opamp there? (im not sure about this tho)....

That was my first thought too. Then I realized it DOES want a 3080/13600 type. This is the Triangle To Sine converter. A BJT diff-pair without NFB will do a first-order bending of triangle into sine-like. Conventional opamps can't easily be worked this way. You can DIY a diff-pair but the intrinsic matching of the chip is a real plus.

[iainpunk]

one CA3060 seems to be used without varying bias current, so the gain should be static, so maybe you can re-design it to take a normal opamp there? (im not sure about this tho)....

That was my first thought too. Then I realized it DOES want a 3080/13600 type. This is the Triangle To Sine converter. A BJT diff-pair without NFB will do a first-order bending of triangle into sine-like. Conventional opamps can't easily be worked this way. You can DIY a diff-pair but the intrinsic matching of the chip is a real plus.

i don't know if available, but a CA3140 and a CA3019 can do the trick of curving the triangle as well, probably won't be as cheap tho.
maybe you can come across a CA3028, which is a cool diff pair in a can

probably better stick to the CA3080 or 13600 OTA

cheers

[PRR]

> CA3140

That's MOSFET. Different curve.

The ploy in the datasheet is a diode-based bender and would work with about "any" opamp.