Good modern op-amps and comparators for stock? - Page 1
Forum section: electronics / projects

author: MrSlack
author_rank: Frequent Contributor
timestamp: December 14, 2015, 11:24:08 am
content: I've got a supply of cruddy old op-amps and comparators floating around. Typical older designs so 741s, 358s, tl072, 324, 311 etc.What is considered a reasonable "modern" general purpose op amp for low frequency applications these days? (sub 5MHz). Split or single rail is fine. DIP packages are a requirement!Also same question for comparators.Intending to buy ~50 of each to get me through the next decade of random projects or so

author: tszaboo
author_rank: Super Contributor
timestamp: December 14, 2015, 12:34:05 pm
content: With 50 of each, you will be spending quite the quid on it. Opamps like OPA2350, 2227, cost 4 dollars at single quantities, imagine you would stock only 10-20 different type.

author: krivx
author_rank: Frequent Contributor
timestamp: December 14, 2015, 12:42:24 pm
content: What's wrong with the parts you have, other than age? Hard to know what to recommend...

author: wraper
author_rank: Unknown
timestamp: December 14, 2015, 01:05:58 pm
content: Quote from: MrSlack on December 14, 2015, 11:24:08 amIf you want something very cheap general purpose, 358 and 324, 311 are still your choice if they meet the requirements. Out of this list I probably wouldn't use 741s but others are still completely fine for new designs.

author: MrSlack
author_rank: Frequent Contributor
timestamp: December 14, 2015, 01:15:49 pm
content: Excellent - thanks all. Will just stick with what I'm used to then and dump the 741s (I rarely use them now anyway)Background: I bought a massive stock in 1998 for discount prices and only just used them all up (got literally one left of each class) so looking to bulk purchase again. I tend to just grab a handful of stuff from Farnell at the first price break. Over time it works out cheaper than hitting other distributors on demand.

author: bktemp
author_rank: Super Contributor
timestamp: December 14, 2015, 02:00:51 pm
content: There is not one perfect op-amp that is ideally suited for every specific application. Depending on the application you need:- cheap ones- rail2rail opamp (there are output only rail2rail opamps and input+output rail2rail opamps. Most of them are 5V, 30V are harder to find and more expensive)- low voltage opamps (5V Vcc are common), often rail2rail- precision opamps, low input bias current opamps, low noise opampsThere are a few opamps that have almost all of above features, but you buy them whenever you need one, because they are really expensive.For general pupose opamps, sort the list from your distributor by price. LM358/324 will be the cheapest ones, followed by many 5V opamps, most likely in SOT23-5.LM324 is probably the most common opamp, because it is the cheapest one (LM358 is cheaper but you only get 2 instead of 4 in one package).I would recommend buying some LM358/LM324 and some rail2rail ones like TS912 or some cheap Microchip MCP6xx. They are not the best ones, but cheap enough to have them in stock. And they are available in DIP8.If you need better ones for a project, buy the type that fits best for the specific application. Otherwise you have to stock hundreds of different opamps.

author: nctnico
author_rank: Super Contributor
timestamp: December 14, 2015, 02:44:49 pm
content: I agree. I see myself using a different opamp in nearly every project due to different requirements.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 14, 2015, 06:03:16 pm
content: For GP R2R, I reach for TLV2372. Good for up to 12V rails.There are quite a lot of low and high performance op-amps out there, but they're 5.5 or 6V max. So if you have a lot of low voltage (usually digital, e.g. ADC front ends / processing) circuits, that's good. If you need 12V included, there seem to be fewer in the 16V or 25V or 30V+ ranges, aside from the good old bipolar ones (LM358, etc.).I still keep LM358 on hand, when I truly don't care what I get (and usually the single supply range is handy). They are truly awful, with crossover distortion even disturbing control loop applications, let alone audio and precision ones. (A bias resistor to -V on the output helps a lot with that. Definitely not a low power solution.)TL072, LF412, etc. are all still great, for when you have excess supply range (i.e., +/-9V or more, say). Try also LM833 (bipolar, low distortion), or LME49710 ("audio' op-amp).Tim

author: dom0
author_rank: Super Contributor
timestamp: December 14, 2015, 08:43:57 pm
content: > LM833Or NE5532/5534, they are essentially identical.

author: MagicSmoker
author_rank: Super Contributor
timestamp: December 14, 2015, 11:04:51 pm
content: No, don't dump your 741s (and keep a few "single supply" LM324 and/or LM358 around too)! The reason why is because it is often useful, or at least instructive, to swap in a crummy/mediocre op-amp to see how the circuit behaves differently.

author: MrSlack
author_rank: Frequent Contributor
timestamp: December 14, 2015, 11:08:31 pm
content: Edit: Good point with the crummy amp suggestion! I've only got a couple of each left but will keep them around anyway.Ok thank you all. I've just gone through all my notes over the last decade to see what I used and the complaints I had and compiled a list and added some others from suggestions so I'm going for:* 20x TL072s* 5x AD822 (these sting a bit so keeping # low)* 10x LM358* 10x NE5532* 10x LM311High quantities because deadbug tends to knacker them if dropping them on the carpet doesn't first

author: tszaboo
author_rank: Super Contributor
timestamp: December 15, 2015, 10:01:19 am
content: Quote from: MrSlack on December 14, 2015, 11:08:31 pmModern? All of these were released more than 20 years ago.I was thinking you are going to stock newer amps. There was like a 1000 times improvement in several different areas in opamps. Now they pretty much reached a point, where you can pick a parameter, which is ideal. Meaning that the passives around them will limit the performance.

author: MrSlack
author_rank: Frequent Contributor
timestamp: December 15, 2015, 10:17:20 am
content: Most of what I do doesn't benefit from anything released in the last 10 years. Plus most of them are unproven availability so far. I notice a lot of modern opamps are short run and suddenly become difficult or expensive to get hold of. So once I've blown up my stock, I may want to reproduce a design in the future as it stands.Currently attempting to build a fully analog pulse oximeter which isn't exactly high bandwidth!Basically, they're more modern than ?A702s and less crappy than the 741s which is good enough

author: MrSlack
author_rank: Frequent Contributor
timestamp: December 15, 2015, 10:50:51 am
content: Similar stock of parts here. I don't do microcontrollers though; too close to the day job (software)

author: MrSlack
author_rank: Frequent Contributor
timestamp: December 15, 2015, 12:00:33 pm
content: I'd love to swap