substitute for CA3260: MOSFET in, CMOS out....?

[idy]

I've used and liked CA3260ez opamps in circuits where opamp clipping happens and like them. They are out of production (?) or just very expensive.

Now I don't know that what I liked was MOSFET input and CMOS output, but playing with that idea, what else can I use?

Is that such a rare/strange/bad combination that it has been abandoned?

[Rob Strand]

The most common one would be the single opamp CA3130.  It was never cheap and I've seen some high prices in recent times.   You might need to dig around for a good price.

There's a few other angles like using CMOS gates or doing a DIY opamp using CMOS 4007 devices.   I'm not convinced you will end-up with a CA3260 and CA3130.

The funny thing about MOSFET opamps is *many* custom chips use fully MOSFET opamp designs inside.  I haven't looked but it makes me think there should be some modern offerings out there.

[idy]

I did see the singles. Not that hard to design strip board around that...
And eBay people have the 3260 down to $5 in lots of 5... but the more reputable places are out I think.

[MikeA]

UTSource has NOS Harris CA3260E in the $1-$2 range, and they guarantee authenticity.  I've bought similar parts from them in the past and the performance matched known-good parts I got from Mouser.  Haven't tried these Harris pieces, though. UTSource also fronts for other suppliers who sell used parts, without the guarantee, so you have to watch who's selling what. 

[idy]

Interesting. At UTSource all the new 3260s, when you look at them or the data sheets, you find they are really 3240, bipolar output.
There are some used 3260s... appear authentic, only $2.83... Who buys used opamps? Me?

[MikeA]

The parts pictured seem to be CA3260, while the datasheet is indeed for a CA3240 with a tiny note stating "data sheet not found, similar data sheet recommended.."

[anotherjim]

Texas TLC series.
https://www.ti.com/lit/ds/symlink/tlc2262.pdf

[Mark Hammer]

I purchased a set of five CA3260 chips through Aliexpress late last year.  Only one of the five was actually functional upon arrival.  I thought perhaps that some singles had been relabelled as duals so I tested out the non-working chips in a single-op-amp circuit, but they were duds.  The 3260 that did work, however, was put into an Ibanez MT10 Mostortion clone I made.  I liked it a lot.  As luck would have it, I also had a 3240 I could stick in the socket, and compared the two chips.  Both worked well, but the 3260 sounded a little different than the 3240 in that circuit, and I liked it a little better.

[iainpunk]

i think the magic in those is the CMOS output stage. i have designed and experimented with the CA3160 and CA3130 (same except the 60 has an extra compensation cap inside) and comparing it with the CA3140 (almost the same differential amp, bipolar output stage) and the 'vibe' from the clipping is way smoother in the 30 and 60 compared to the 40.

then there's a way to get the CA3130 or CA3160 to self bias which is really cool as well, but youre stuck with using it as an inverting gain stage. it uses the self-bias capabilities of the CMOS stage to do this.

cheers

[idy]

tlc2262 seems worth a try.
It is good to know others hear a difference. BYOC used to offer 3260 as an option in their tubescreamer OD2; but unless you lift the diodes I think it is wasted there.

[anotherjim]

tlc2272 also (seems harder to get over here in DIP). These are Tech21's goto clipping opamps while they use other more common types for the clean work.

[Rob Strand]

Texas TLC series.
https://www.ti.com/lit/ds/symlink/tlc2262.pdf

Good one jim.  LinCMOS is family.

[Mark Hammer]

While I've got you all here, I bought some TL054 quad op-amps by mistake.  https://www.ti.com/product/TL054
Is there anything in particular you would recommend using them for, and anything you would caution against using them for?

[Rob Strand]

While I've got you all here, I bought some TL054 quad op-amps by mistake.  https://www.ti.com/product/TL054
Is there anything in particular you would recommend using them for, and anything you would caution against using them for?

They are just a TL07x with slightly up'ed performance.

From the datasheet,
https://www.ti.com/lit/ds/symlink/tl054.pdf

"Direct Upgrades to TL07x and TL08x BiFET Operational Amplifiers"
The opening statements go through the list. 
The main ones I'm seeing are:
better DC offset, better DC drift and higher slew-rate.
I'm not seeing any great improvement in bandwidth.

Not enormous improvements but improvements which sometimes help some applications.
For example, for a precision rectifier the higher slew-rate helps reduce the error and so
does the lower offset.  The lower drift might will also help here.

The idea is you can use them anywhere you can use a TL07x.   Where not to use
them is more a matter of where not to waste their improved characteristics.
If you have heaps of them or just want to use them then use them in
any place you want to try another opamp.

[Mark Hammer]

Thanks, Rob.  They were cheap, so I don't mind "squandering" their better characteristics.  I just didn't want to stick them in somewhere where they might work against the circuit and leave me wondering why it wasn't working right.

[Rob Strand]

I just didn't want to stick them in somewhere where they might work against the circuit and leave me wondering why it wasn't working right.

I guess with with any modern/faster opamp there's always risk of circuits oscillating, especially if they don't have a feedback cap like this,



I'm sure the TL054 is has been designed to keep that problem down to a minimum but there's always circuits that step too far over the safe-practices line and cause problems.

[Kevin Mitchell]

Avoid UT source unless you're desperate. They are notorious for supplying fake & dead parts. I can imagine it's only worse now than ever - which is likely why their sales department called me a few weeks back for customer relations. The pusher man don't care.

However you can dispute a bad order but only with certainty. I got a little hostile with them once as they fought me on my accusations of them supplying me oh-so obvious fake parts. Sadly it was the only way I could get a refund rather than a credit. Plus I don't like people disputing what I know to be absolute facts just so they can keep money they scammed me out of.
After I placed an order I watched them change their stock quantities, marked down prices dramatically compared to what I paid and fulfilled my order outside of their inventory without any notice to me. I literally just watched them do sketchy stuff with my order as they manipulated their inventory & pricing so the next guy wouldn't be as upset when they get fake crap.

End rant lol.