SIGforum
Finding alternatives for obsolete electronic parts
January 03, 2019, 05:54 AM
mark123Finding alternatives for obsolete electronic parts
I had a source for LM308 ICs in the metal can form (designated UA308HC) but some company discovered it and completely wiped them out. I could get a few on eBay but there are rumors of counterfeiting and relabeling going on (LM301s relabeled as LM308s).
I'm wondering if there are other options such as using a dual op amp version of the LM308. Is there an easy way to find a designation for a dual version of a single op amp?
January 03, 2019, 08:12 AM
95flhrHere is a replacement guide that I've used in the past
http://www.nteinc.com/ecg/They show;
Replace part... With NTE part... Product Line Data Sheets Distributor Inventory Notes
UA308HC NTE938 Semiconductors
“Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves.”
― Ronald Reagan
Retired old fart
January 03, 2019, 08:21 AM
pbslinger"I said, "Do you speak-a my language?"
He just smiled and gave me a vegemite sandwich"
January 03, 2019, 09:43 AM
mark123quote:
Originally posted by 95flhr:
Here is a replacement guide that I've used in the past
http://www.nteinc.com/ecg/They show;
Replace part... With NTE part... Product Line Data Sheets Distributor Inventory Notes
UA308HC NTE938 Semiconductors
Cool, thanks!
quote:
NTE938 is a discontinued device and no longer available.
I wonder if it says what to replace NTE938.
I'm check the site when I get to a desktop. I can't get much done on this small screen.
January 03, 2019, 10:27 AM
46and2Someone likes RAT-esque distortion pedals / circuits.
(Sorry, no leads on equivalents)
January 03, 2019, 12:15 PM
mark123quote:
Originally posted by 46and2:
Someone likes RAT-esque distortion pedals / circuits.
(Sorry, no leads on equivalents)
Yep, I'm working on a variant with a few extra options. So far I've only built one for myself.
I'm not convinced the LM308 sounds much different than the OP07, at least not in a band context. The LM301 also may be an option as they are a bit kinder and smoother. But why get a RAT for that?!
January 03, 2019, 12:54 PM
46and2I suspect BYOC and the plethora of clone builders have gobbled up most of the vintage ones. And nowadays there are more pedal builders than ever, it seems. Depending on NOS parts in a given circuit these days is a long row to hoe. If you just need a few it's probably doable, to find them, or harvest, but more than that will be difficult I'm sure. Good luck.
Sort of similarly, a few months ago I had a lengthy conversation with AnalogMike about the differences between the various Germanium transistors found in his Sun Face and all of the other Fuzz Face clones and variants and he's convinced most would never notice the differences in a band context. I generally agree. So much is made over this Capacitor vs that Transistor vs such-and-such OpAmp that I think it gets overblown a fair bit.
Meanwhile, just to cover my bases, I have at least one of the classics (new and old) that interest me, and I mostly only play vintage amps, but I do question its actually necessity.
January 03, 2019, 01:25 PM
95flhrquote:
Originally posted by mark123:
quote:
Originally posted by 95flhr:
Here is a replacement guide that I've used in the past
http://www.nteinc.com/ecg/They show;
Replace part... With NTE part... Product Line Data Sheets Distributor Inventory Notes
UA308HC NTE938 Semiconductors
Cool, thanks!
quote:
NTE938 is a discontinued device and no longer available.
I wonder if it says what to replace NTE938.
I'm check the site when I get to a desktop. I can't get much done on this small screen.
Mark,
Try here.
https://www.elliottelectronics...r=relevance&dir=descLooks like they may have a couple in stock
“Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves.”
― Ronald Reagan
Retired old fart
“Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves.”
― Ronald Reagan
Retired old fart
January 03, 2019, 03:35 PM
mark123quote:
Originally posted by 46and2:
I suspect BYOC and the plethora of clone builders have gobbled up most of the vintage ones. And nowadays there are more pedal builders than ever, it seems. Depending on NOS parts in a given circuit these days is a long row to hoe. If you just need a few it's probably doable, to find them, or harvest, but more than that will be difficult I'm sure. Good luck.
Sort of similarly, a few months ago I had a lengthy conversation with AnalogMike about the differences between the various Germanium transistors found in his Sun Face and all of the other Fuzz Face clones and variants and he's convinced most would never notice the differences in a band context. I generally agree. So much is made over this Capacitor vs that Transistor vs such-and-such OpAmp that I think it gets overblown a fair bit.
Meanwhile, just to cover my bases, I have at least one of the classics (new and old) that interest me, and I mostly only play vintage amps, but I do question its actually necessity.
You know Analogman? Sweet! The King of Tone is one of my favorites.
I'm convinced that "mojo" is baloney. Various ICs in a soft clipping circuit, like a tube screamer, doesn't amount to much, if anything at all. However, in a hard clipping circuit like the Rat you can hear different ICs. Of course, in a band context it's all superstition. I've never been convinced that capacitor types make a difference.
Before I got my hands on a couple UA308HCs I just used a LM301 in my RAT. It sounded rather excellent but the 308 did have that classic RAT sound. I think the tone control contributes more than the IC. There is a difference but no one's going to pick it out unless I tell them.
January 03, 2019, 03:41 PM
mark123Thanks for the links 95flhr. I'm going to pick up a few and A/B them with a LM308.
January 03, 2019, 04:34 PM
DraalI haven’t built pedals for a few years but I remember that Rat IC is unique. Something about it’s slew rate giving it that classic vibe. There are subtle differences in a number of ic’s but the Rat lovers want that 308. It’s a selling point for sure regardless of the hype lol!
I was cleaning the man cave and found a couple of Russian npn germanium in the 130ish HFE range. I see another Fuzz build soon....
Good luck in your search!
January 04, 2019, 05:50 AM
r0gueI wonder if that component might be common in some old electrics you can find for cheap at thrift shops.
January 04, 2019, 06:00 AM
mark123quote:
Originally posted by r0gue:
I wonder if that component might be common in some old electrics you can find for cheap at thrift shops.
Yes, I was thinking the same thing. If there's an untapped source, such as a long forgotten kid's toy, I could scavenge.
January 04, 2019, 03:08 PM
46and2It definitely happens. One particular chip that's popular in the Roland synthesizer world because it's used in famous VCFs like that in their Jupiter 8 can also be harvested from certain 80s era BOSS pedals, but it's tedious and you have to ruin a pedal to get them.
Also, nowadays, companies like Cool Audio are recreating old chips that weren't being manufactured anymore, as the analog resurgence continues on in recent years, though that's primary in the synth world, so who knows.
I've never looked deeply into these, I just know they're popular for RATs and (as stated above) it's mostly because how they handle Slew which makes them unique.
Have you tried MuffWiggler? There are a lot of uber nerds of the DIY synth variety there, and there are eurorack modules which are a RAT in a different format, so someone over there might have a lead on some. How many are you looking for?
February 06, 2019, 08:09 AM
mark123I found a source for a small number of LM308. They're reputable but I would still like to verify that these chips are not counterfeit (such as an LM301 that's simply been restamped). I don't know if their source was also reputable.
How would I go about testing them?
February 06, 2019, 10:13 AM
radiomanI don't understand why you can't use any number of similar op-amps if you can't find an LM308. There are a ton of them out there.
and you mentioned the metal can. Why do you need a metal can?
.
February 06, 2019, 10:27 AM
mark123quote:
Originally posted by radioman:
I don't understand why you can't use any number of similar op-amps if you can't find an LM308. There are a ton of them out there.
It's a tone chaser thing. The LM308 does sound legitimately different.
quote:
... and you mentioned the metal can. Why do you need a metal can?
I don't. They were, at one time, more readily available.
