Amazon CA3240EZ Op-Amp

[Huntress]

Found these on Amazon but I don’t know if I should trust them at this price? Everywhere I look in Canada they are $4.80-$5.11 per unit. How can I tell if these are genuine CA3240EZ op- amps?

 

[zgrav]

you could risk spending $15 or so to find out. there are cheaper sources from china on ebay for the chip, so that probably accounts for the supply for this seller.

 

[Laundryroom David]

Short answer is: you really can’t.

My spidey senses tell me that this is going to likely be fake.

 

[Locrian99]

It’s tough I’ve had it to both ways. I’ve found an eBay seller wirb 3207/3102 sets I have bought several of all work great for 1.50ish a pair. I’ve gotten burned on every charge pump I’ve bought. It’s just a risk vs reward really in my experience.

 

[Laundryroom David]

It’s tough I’ve had it to both ways. I’ve found an eBay seller wirb 3207/3102 sets I have bought several of all work great for 1.50ish a pair. I’ve gotten burned on every charge pump I’ve bought. It’s just a risk vs reward really in my experience.

I’ve had much better luck on eBay than Amazon, but it’s a dice roll every time. I’ve said it before and I’ll say it again - buying off eBay and Amazon is sort of like going to a casino: don’t pay more than you’re prepared to lose

 

[Laundryroom David]

Found these on Amazon but I don’t know if I should trust them at this price? Everywhere I look in Canada they are $4.80-$5.11 per unit. How can I tell if these are genuine CA3240EZ op- amps?View attachment 54119

You might check this thread to see if it helps at all
Thread 'Face Melter IC'
https://forum.pedalpcb.com/threads/face-melter-ic.3473/

 

[Cybercow]

MOUSER

 

[Huntress]

You might check this thread to see if it helps at all
Thread 'Face Melter IC'
https://forum.pedalpcb.com/threads/face-melter-ic.3473/

Thanks I’ll check it out.

 

[jwin615]

Always wanted to order a couple of these.

If you have the kit to do so, can compare 2 different opamps.

 

[Huntress]

Always wanted to order a couple of these.

If you have the kit to do so, can compare 2 different opamps.

Thanks. This is very interesting unfortunately this will be my first build and I don’t know to much about electronics.

 

[Laundryroom David]

Thanks. This is very interesting unfortunately this will be my first build and I don’t know to much about electronics.

Definitely want to socket the IC. Fwiw I think you’d be fine to sub a TL072.

Canadian seller, reputable, small business:

IC Socket - Precision Tooled 8-Pin

Precision tooled 8-Pin IC socket for integrated circuits. A must have for solder circuits with ICs in them as they avoid the need to solder directly to the IC, which is very susceptible to heat damage. Solder one of these to the board, then press-fit your ICs into place in a secure socket...

nextgenguitars.ca

Also check Solo for various parts. Another reputable small business and in Canada.

SOLO Music Gear - Best DIY Guitar Kits, Guitar Store Near Me, Strat Kits & Services Canada

www.solomusicgear.com

I actually prefer the cheaper cinch sockets from Tayda or Digikey but I also really like supporting Nextgen, which is as close to local as I can find.

 

[Alan W]

Thanks. This is very interesting unfortunately this will be my first build and I don’t know to much about electronics.

I’d recommend giving in to the high price of a known chip then—you’ve got all sorts of good times ahead, but troubleshooting is generally not fun (until it is!) and a faulty chip can complicate things.

You’ve found a good community of co-travelers here.

 

[Chuck D. Bones]

It's easy to measure the bias current with a breadboard & a DMM. That's a good test to see if it has a CMOS input stage. Fake ones won't be CMOS.

you're putting this in a Pu55y Melter, right? The other way to solve the IC supply problem is to switch over to a CA3140. Those are readily available. The CA3240 is a dual CA3140. Since the PM only uses on half of the CA3240, you can do a little surgery on the board and use a CA3140. We can only guess why Steel Panther would put a dual opamp on the board and only use half of it. There are other questionable design decisions on that board, but that's out of scope for this discussion.

 

[Huntress]

It's easy to measure the bias current with a breadboard & a DMM. That's a good test to see if it has a CMOS input stage. Fake ones won't be CMOS.

Thanks. But again I’m new to the electronics game like this so I don’t know much about testing with breadboards. I am having to learn everything from scratch.

 

[Laundryroom David]

I breadboarded it with a single op amp and was working on a schematic and layout but then got derailed by my actual job. I also wanted to simplify the components in the moist/gushing path. It’s a fun pedal and sounds good. Would be good to have a redesign that makes better use of the space and uses more readily available components. I’ll try to get back at ‘er…

 

[Chuck D. Bones]

If you are buying semiconductors on eBay or Amazon, you must be able to test them. Otherwise, you will wind up with Fugazi parts. Too many sellers on Amazon & eBay know less than you do about the stuff they're selling. Hanlon's Razor notwithstanding, there are probably some unscrupulous sellers who deliberately sell crap too.

Something else to think about: CMOS parts are very susceptible to ESD (static electricity) damage. If the seller or their supplier do not handle and package the parts correctly, you could end up with wounded parts. I returned a microprocessor on eBay because it was not packaged properly. The seller apologized and admitted that they had no clue how to properly handle CMOS.

 

[Chuck D. Bones]

I breadboarded it with a single op amp and was working on a schematic and layout but then got derailed by my actual job. I also wanted to simplify the components in the moist/gushing path. It’s a fun pedal and sounds good. Would be good to have a redesign that makes better use of the space and uses more readily available components. I’ll try to get back at ‘er…

Sounds like your work/life balance is outta whack

We should talk off-line about the other dipshittery in that circuit. You can save a few more parts and have the same tone...

 

[Laundryroom David]

Sounds like your work/life balance is outta whack

We should talk off-line about the other dipshittery in that circuit. You can save a few more parts and have the same tone...

Oh man, is it ever.

Yeah that sounds good!

 

[Huntress]

If you are buying semiconductors on eBay or Amazon, you must be able to test them. Otherwise, you will wind up with Fugazi parts. Too many sellers on Amazon & eBay know less than you do about the stuff they're selling. Hanlon's Razor notwithstanding, there are probably some unscrupulous sellers who deliberately sell crap too.

Something else to think about: CMOS parts are very susceptible to ESD (static electricity) damage. If the seller or their supplier do not handle and package the parts correctly, you could end up with wounded parts. I returned a microprocessor on eBay because it was not packaged properly. The seller apologized and admitted that they had no clue how to properly handle CMOS.

I know a little about CMOS handling and a tiny bit about electronics. Enough to be dangerous lol. Built a few computer but nothing like this. My engineering brain is tickled by stuff like this so I should be able to figure out everything and if not I have this amazing forum to confide in.

 

[xefned]

The part that will bother you is not knowing what chips you're buying.

The ones from Amazon will work, but you'll never know if they're a relabeled 4560d, a relabeled LM258, a relabeled TL052, a relabeled TL082, etc. etc. etc. It gives you no point of comparison.

If you're OK with a different chip, get a TL072 and you'll know what you’re starting with.
But if you want it to be a genuine Intersil, you have to get it from Mouser, Digikey, or Newark.