EEVblog #658 - Mailbag - Page 1
Forum section: electronics / general

author: senso
author_rank: Frequent Contributor
timestamp: August 31, 2014, 10:45:14 pm
content: This must be the most on time Mailbag Monday ever, its still Sunday here(in Portugal).

author: N2IXK
author_rank: Frequent Contributor
timestamp: August 31, 2014, 11:32:42 pm
content: Looks like the high voltage generator for the VFD is the transistor and coil/transformer above the tube, not part of the LSI chip.

author: mfeinstein
author_rank: Contributor
timestamp: September 01, 2014, 12:31:54 am
content: I guess I saw a post card from Brazil on the table....I am curious Dave, have you had other projects (or mailbags) from Brazil before?Be sure as soon as I finish mine (which will take still some lots of months hahaha) I will surely send you

author: lowimpedance
author_rank: Super Contributor
timestamp: September 01, 2014, 12:59:32 am
content: The Keithley 177 was also sold to and re badged by Racal as the model 4003. And some time ago I came across an ebay picture of the 4003 schematic which is posted at this thread;https://www.eevblog.com/forum/testgear/looking-for-keithley-177-dmm-schematic/msg385208/#msg385208and is surprisingly very readable (much much better than the copy in the manual PDF).The other thing to note with these meters is the current ranges share the same input terminals as the volts and ohms and the fuse is internal (which I noted in the video is missing)

author: dentaku
author_rank: Frequent Contributor
timestamp: September 01, 2014, 01:38:10 am
content: I love those old displays.You've got to do a video on different display technologies someday and a fundamentals video on multiplexing.

author: coppice
author_rank: Super Contributor
timestamp: September 01, 2014, 02:37:29 am
content: Its interesting that calculator is labelled Commodore. I seem to remember at that time most of their machines said CBM on the front.

author: all_repair
author_rank: Frequent Contributor
timestamp: September 01, 2014, 02:58:50 am
content: The Sharpiese I could use a few. Now I am taping a piece of magnet over mine. Hope he can run again for brighter color (so they can be found), and at a lower price.

author: EEVblog
author_rank: Unknown
timestamp: September 01, 2014, 05:46:48 am
content: Quote from: senso on August 31, 2014, 10:45:14 pmRelease 9am Monday morning Sydney time.

author: robbak
author_rank: Contributor
timestamp: September 01, 2014, 07:38:46 am
content: Well then, there's enough time do another one and still be Monday (somewhere).Oh, are you sure that is a cap on that chip? To me it looks like today's flip-chip designs, where the bare die is bonded to the substrate upside-down, and epoxied down around the edges.Did they do that sort of thing back then?

author: dentaku
author_rank: Frequent Contributor
timestamp: September 01, 2014, 01:11:55 pm
content: Quote from: coppice on September 01, 2014, 02:37:29 amWhen I was in grade 7 and 8 we had a desktop model Commodore calculator. I seem to remember it was labeled as Commodore and not CBM.It was something like this.http://www.classiccmp.org/calcmuseum/Commodore412.jpg

author: JoeO
author_rank: Frequent Contributor
timestamp: September 01, 2014, 01:14:31 pm
content: 30 years ago I bought some Radio Shack surplus boxes. In them were 4, LC1552-B 40 pin dips. Now I know what the are, calculator chips.Thanks Dave.

author: jeremybarker
author_rank: Newbie
timestamp: September 01, 2014, 04:47:30 pm
content: Oh wow!! I got hold of one of those CompuCorp calculators about 25 years ago (including the power supply) and they are a really nice piece of machinery. They have a lovely orangey-red Burroughs Panaplex display. Mine works but it's currently stored away somewhere and would take ages to find. I did take mine apart but won't spoil it for eveyone by describing the insides.

author: Legit-Design
author_rank: Frequent Contributor
timestamp: September 01, 2014, 07:43:50 pm
content: Sound from face shot is totally different to bench shot, you voice sounds much higher and could be more annoying. Maybe try to standardize on some microphone to make both sound the same, I think canons sound ok. But the video from that Sony on face shot looks good.

author: Dave
author_rank: Super Contributor
timestamp: September 02, 2014, 05:29:44 am
content: That VFD is pure porn.I have some IV-21 tubes in my parts bin, which look a lot like that tube in there (except the connections are on the other side). Gonna have to use them in a project.

author: richfiles
author_rank: Regular Contributor
timestamp: September 02, 2014, 07:55:00 am
content: Just a small selection from my own personal collection. I'm setting up space to better display them, and plan to move more out of storage. I have examples ranging from 1961 to 1990s represented between just those two pics! I actually have well over 100 vintage calculators from the 1960s and on, as well as a couple REALLY ancient pre-electronic era ones, including a Burroughs Manual. My collection spans both desktop and handheld models... And I really need to get them all documented!I love some of my old Commodore calculators! I have several different models, including my favorites, the S-61 Statistician and the N-60 Navigator, along with a PR100 programmable. There are plenty of others in my collection, but once you see those... nothing else Commodore made in the pocket market even compares! The N-60 and S-61 have 60 keys each (the S-61 has an additional switch). Most of those have a second function! Both use VFD displays. The PR100 is their higher end programable model and used a red LED display.I have my own Monroe (rebranded Compucorp) and another different model Compucorp. My Monroe 344 Statistician, with dual program banks is fully functional. The other one's broken. Also in storage, so I forgot the model. I've read they were very susceptible to static discharge.Trust me, you are going to LOVE the Compucorp tear down. If I recall, there are 4 layers of PC boards. It has a Power PCB, a Memory PCB, a Processor PCB, and an I/O PCB. It was very modular, and they used a crazy interconnect to bus the boards together.The display is a 16 digit Panaplex neon gas display. It glows orange, like a nixie tube, but uses segmented digits. I do believe it displays 10+2 digits, with inline (-) symbols.The 2ND FUNC key is very unusual on these models. You press it AFTER performing the desired function. The calculator actually calculates for BOTH function's result, and the key toggles which result is displayed, and is used for the next operation. This leads to an unfortunate bug, however, where if you perform a calculation that is valid on one function, but would generate an error on the other, it will error out the calculator. Oddly enough, on at least some models, you could press the RESET key and clear the error, but you could STILL press 2ND FUNC to swap the other (valid) result in!And yes... This thing is an absolute BEAST! I love it!Still not as heavy as my SCM Cogito 240SR (The BIG calc with the blue colored CRT) or my Friden EC-132 (in storage)... Of course, this one IS "portable", what with it'sQUAD"D" type batteries!?And now for some bonus calculator porn...A shot from my restoration of a Sony SOBAX ICC-600W... striped down! Enjoy!How about a Russian beauty. She's shy though... This Elektronika 4-71b is only half covered!

author: eV1Te
author_rank: Regular Contributor
timestamp: September 02, 2014, 08:30:01 am
content: Good luck with fixing/calibrating the Keithley 177 that I sent to you, and I hope we all learn something new in the processBoth your video and Ben Krasnows came very appropriately, within one day both of my donations came online!But I hope you are not jealous because I sent a bigger and more expensive donation to Ben Krasnow?https://www.eevblog.com/forum/testgear/video-operation-of-a-scanning-electron-microscope-at-home-in-my-living-room//Best wishes Richard Andersson

author: coppice
author_rank: Super Contributor
timestamp: September 02, 2014, 10:35:38 am
content: Quote from: richfiles on September 02, 2014, 07:55:00 amI used to use a Casio that was somewhat like that Sony, but with some programmability. Its interesting how may digits they put on some of those early calculators. Each digit incurred considerable extra cost, so I never really understood the prevalence of this kind of design.

author: richfiles
author_rank: Regular Contributor
timestamp: September 02, 2014, 09:37:58 pm
content: Quote from: coppice on September 02, 2014, 10:35:38 amI suspect that it was to compete with mechanical models of the day, which were unite still prevalent. The electronic models cost more, but if you needed more digits, or valued silence, they were a Godsend! You COULD get mechanical models with a lot of digits... Like my Friden STW-10... But watching the thing is like watching a typewriter have a seizure!It was a gimmick, I'm sure, for some of them. Others wanted to impress, and make them selves look so much better. You have to remember, it was a "war" back then, with literally hundreds of companies popping up in the trailing years of this type of machine, just as large scale integration became prevalent. Sony REALLY bet on the wrongformattechnology when they went with hybrid modules. They did all their designs for hybrids, because integrated circuits looked so far off, with how many the US military bought, and the expense of the parts. In the end, they brought this to market as small scale integration be can to REALLY take off. in only 2-3 years, this machine and it's technology was BEYOND obsolete.Hey,at least Sony finally got one right with Blu Ray!

author: robrenz
author_rank: Super Contributor
timestamp: September 04, 2014, 10:36:39 pm
content: I believe the grad on the calculator is grads not radians. 400 grads = 360 degrees