OK, you've seen the 555 kit, now here's the discrete 741 kit. - Page 1
Forum section: electronics / projects

author: Rory
author_rank: Frequent Contributor
timestamp: June 27, 2014, 02:50:32 am
content: The "Seven-Forty-Fun"...https://squareup.com/market/open-analog

author: zapta
author_rank: Super Contributor
timestamp: June 27, 2014, 03:03:09 am
content: I liked the eevblog #555 video. This is a good candidate for #741 + explanation of the differential current mirroring thing.

author: Mr. Coffee
author_rank: Regular Contributor
timestamp: June 27, 2014, 03:49:23 am
content: Just wait until I build one with vacuum tubes! It'll be the biggest chip you ever saw...you'll be sorry! LOL

author: Bored@Work
author_rank: Super Contributor
timestamp: June 27, 2014, 05:50:20 am
content: Quote from: Mr. Coffee on June 27, 2014, 03:49:23 amYou are several decades to late. Google "Philbrick Researches". Their tube op-amps were the first commercially available ones in the 50th. Earlier they had some for special purposes, too. And their amplifiers were not as big as you would probably think.Still until today Analog offers Philbrick's 1966 application book for download.http://www.analog.com/library/analogdialogue/archives/philbrick/computing_amplifiers.pdfCompare that with all those pathetic "Hey dudes I'll teach you all about opamp circuits in five minutes on youtube" stuff.There are of course also the audiophools who build tube op-amps today. But that is another story.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 27, 2014, 06:32:31 am
content: Curious how you'd do it, without P type toobs. Hybrid substitute? Too dubiously cheaty, too easy to get the performance way up I'd think (say by inverting the design so tubes take on the task of lateral PNP). But without an active current source, you can't very well approach the performance (output swing and supply range). Also, a complementary output stage would obviously be a bit of a problem; something like NE5532 (if I'm remembering right) might be a better choice. No shortage of op-amp designs to pick from, even if it's not the famous 741.Offhand, I would guess a good op-amp (not like the original K2-W with low output drive, but something sizable with good gain and linearity) would take on the order of 5A heater power (at 6.3V). Not a big chassis, but it would be pretty toasty. The main downside is, if you've ever seen an original plugin for a Tek 500 series scope, you need about that much hardware... for perhaps the performance of just one stage out of the whole plugin!Tim

author: Joule Thief
author_rank: Regular Contributor
timestamp: June 27, 2014, 07:20:25 am
content: Quote from: Bored@Work on June 27, 2014, 05:50:20 amThank you for the link. Somehow the author's style "speaks" to me.+1 for the old timers.

author: Mr. Coffee
author_rank: Regular Contributor
timestamp: June 29, 2014, 04:25:11 am
content: +2 for the old timers. They knew how to explain the why, then the equations. Almost all of my most enlightening books are pre 1960s.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: June 29, 2014, 04:55:38 am
content: Haha that article is awesome:QuoteQuote

author: TerraHertz
author_rank: Super Contributor
timestamp: June 29, 2014, 11:13:57 am
content: Quote from: Rory on June 27, 2014, 02:50:32 amThat's cool. But whhhhhyy did they arrange the IO pins (two rows of 4 pin sockets at top left) that way? You cannot plug the thing straight into an existing 741 socket. Which would seem to be just about the #1 point the designer should have aimed for.Quote from: Bored@Work on June 27, 2014, 05:50:20 amThanks for that! Looks like a fun read. I'm already in love with it just from the sticky taped layout of page 1. Because why invest in layout rubber glue when you have magic tape?Also, bonus - several good examples of bad scanning technique, useful for something I'm writing atm. Pity the person(s) who scanned the book weren't as thorough as the authors.

author: Bored@Work
author_rank: Super Contributor
timestamp: June 29, 2014, 11:42:48 am
content: Quote from: PedroDaGr8 on June 29, 2014, 04:55:38 amYes, there is some good fun in the book. Any technical writer writing something like this in a corporate publication today would be fired on the spot. One starts to get an idea where the likes of Bob Pease (one of the authors) developed their writing style.Quote

author: bwat
author_rank: Frequent Contributor
timestamp: June 29, 2014, 12:12:47 pm
content: Should you plot the historical quality of things, you would see that the trajectory taken by technical manuals coincides exactly with the trajectory taken by pop music - both being driven by the cold war which started in earnest in the 1950s and was dead and buried by 1990.

author: TheRuler8510
author_rank: Regular Contributor
timestamp: June 29, 2014, 03:55:10 pm
content: Quote from: Rory on June 27, 2014, 02:50:32 amNice...cool...awesome. Thanks for telling us about this. I'm going to buy one right away!Regards,Tom

author: Mr. Coffee
author_rank: Regular Contributor
timestamp: June 30, 2014, 07:56:20 pm
content: Quote from: bwat on June 29, 2014, 12:12:47 pmWith few exceptions.