Author Topic: DIP14 ua741pc? (Semi-off-topic)  (Read 735 times)

iainpunk

DIP14 ua741pc? (Semi-off-topic)
« on: October 17, 2018, 09:04:34 AM »
So... I was looking at all the DIP14 ic's i inherited from my grandpa (he was an electronics engineer) and found a ic which has the marking μA741PC on it. The first thing i thought was: WOW a dual 741!
That thought turned out to be false. Fact to the matter is that the pinout is as follows:

Soooo...... Its a single opamp with 7 unused pins.
This led me to my question; why does it exist? I mean, its a cool trick to clip off all the 'nc' pins and socket it as a normal 741 and nail polish it red or something (so you can claim its a special 741opamp with "mojo"), but whats the advantage? According to information about the ic it uses the same mask as the normal 741, so its not better or something. Its just.... Odd

Hope this was entertaining  :icon_wink:
If we don't study the mistakes of the future, we're bound to repeat them for the first time.
-Ken M

EBK

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #1 on: October 17, 2018, 09:37:30 AM »
Interesting.  I hope someone has an answer.  I can only make wild guesses.
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duck_arse

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #2 on: October 17, 2018, 09:37:49 AM »
I believe the LM308, among others, also come in the lazy-14 pin pack.

[how can you be off-topic in the first post in a thread you've started?]
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antonis

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #3 on: October 17, 2018, 10:08:13 AM »
[how can you be off-topic in the first post in a thread you've started?]
You owe me a brand new keyboard..!!!  :icon_mrgreen:

(I have to take in mind NOT to drink coffee or any other shorting liquid while reading your posts..!!)
« Last Edit: October 17, 2018, 10:10:34 AM by antonis »
Can't follow your signature changes, Stephen..!!
but I like what follows:
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zombiwoof

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #4 on: October 17, 2018, 10:20:35 AM »
Isn't a 1458 basically a dual 741?.  I've see them used to mod the older DOD OD250 reissue pedals that had a 4558 in them (they only used half of the 4558), to replace the 4558 with something to sound more like the gray OD250's with 741's in them.
Al

anotherjim

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #5 on: October 17, 2018, 12:13:01 PM »
The 14pin was one of the first DIL packages used. A lot of early IC's appeared in it. There used to be commercial products with pcb design for 14pin DIL, but shipped with an 8pin fitted, or even the metal can top-hat package. Whatever was cheapest at build time.
To be a true dual 741, I suppose it ought to have the offset pins too. The dual I know was the 747.

But yeh, I too believe the 1458 behaves like a 741 with no offset connection.

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He is Spartacus!

Mark Hammer

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #6 on: October 17, 2018, 01:37:07 PM »
The Raytheon 4739, that Craig Anderton regularly used in his projects, was also a 14-pin chips; a dual op-amp with a bunch of unused pins.  I don't know how it happened, but when Panasonic came up with their higher-capacity BBDs, they were made using a 14-pin form factor, but with empty spaces where the 3 middle pins would have been on each side.

vigilante397

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #7 on: October 17, 2018, 04:40:21 PM »
My only guess is that whoever doing the die layout wasted space and the die for the chip was bigger than would fit in a DIP-8. Just a guess though, as this:
Quote
The 14pin was one of the first DIL packages used. A lot of early IC's appeared in it.
makes a bit more sense.
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PRR

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #8 on: October 17, 2018, 06:13:11 PM »
The predecessor '709 is listed in both 8 and 14 leg. I recall a lot of them in long-form.

My poor memory says the 14-DIP was widespread long before the 8-DIP appeared.

The IC packages appeared for Logic before Linear. 8 pins is just enuff for two 2-in gates or three inverters, which is not enough "guts" to justify a package. 14 pins allows four 2-in gates, which is a nice mouthful. So the initial boom was in 14-DIP packages, and were used even for single opamps which only need 5 to 8 pins. Yes, probably came off the same wafer whatever leg-count it ended up with.

It does strongly suggest (not prove) that your '741 is "vintage". I have not seen a 14-leg '741 since the very early 1970s. It is *possible* the 14-DIP persisted for specific very conservative applications (the military) which demanded "exact" replacement parts (including dud legs); but more likely yours is just old. I do not know ANY reason to prefer a "vintage" 741; it was as good as it got right from the '101 and later tech-improvements all got new names/numbers.

thermionix

  • Guest
Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #9 on: October 18, 2018, 05:11:05 AM »


I'm confused by this diagram (Pins 3/4).

But I say, use it in something.  Perf up a Dist+, plenty of extra room.  I have an LM10 in mine, just because it's unusual (and it was free).  Sounds exactly like a brand new 741.

anotherjim

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #10 on: October 18, 2018, 05:44:22 AM »

Yes, lazy internet causes persistence of ancient errors  :icon_eek:
The wiggle to the inverting input wiggles the wrong way!
Pin labels are correct.
I am restrained by law from answering any thread that Antonius is currently answering.

He is Spartacus!

iainpunk

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #11 on: October 18, 2018, 09:59:55 AM »
Eyy, thanks for the replies!
I think that the popularity of 14 pin packages makes a lot of sense!
The 2 741ís i have in 14 dip were both in a box of ic's he bought in 1976, in the October and December trays (he [my grandfather] had everything packed in chronological order[he probably had autism or ocd, which would explain why i have autism])

I am probably putting one in a mid-booster /overdrive which i have planned for my next project.
Gonna be a birthday gift for someone special :icon_redface:
If we don't study the mistakes of the future, we're bound to repeat them for the first time.
-Ken M

roseblood11

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #12 on: October 18, 2018, 12:32:39 PM »
Has there ever been a quad version of the 741?

anotherjim

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #13 on: October 18, 2018, 01:23:44 PM »
LM348 is a quad 741. Standard 14pin quad pinout too.
I am restrained by law from answering any thread that Antonius is currently answering.

He is Spartacus!

PRR

Re: DIP14 ua741pc? (Semi-off-topic)
« Reply #14 on: October 18, 2018, 04:47:00 PM »
Generally, the first rush was to copy the single '741, then to introduce "improved 741s". Only as that gold-rush ebbed did makers move to putting more in one package. So many dual and quad "741" are "improved 741" types. (The improvements are often too modest to care about at this late date.)

'148/'348 is blurbed as quad true '741.

IIRC the quad RC4136, "similar to 741", came out before the 'x38 types, and is seen in many early pedal plans, but has a pinout which did not become The Standard.