Silicon Archaeology : ICL7107 - Page 1
Forum section: electronics / general

author: free_electron
author_rank: Super Contributor
timestamp: April 08, 2013, 05:12:19 am
content: I wad digging around in the local junkstore when i spotted a rusty metal box , painted in hammerstrike gunmetal , flaked , chipped, display cover missing. I was going to toss it aside when i spotted, through the display opening (missing red display cover), what looked like a white ceramic IC inside. An old dymo embossed style label said 0...1.999 volt. Hmmm... curiosity peaked i asked what they wanted for it ... 2$ ... at that price i couldn't let it go... Homeward it went.After taking the cover off here is what if found :An original , intersil built ICL7107 dual-slope voltmeter IC in ceramic package with side-brazed gold pins !. Holy moly. That thing is old ! And this is an intersil original evaluation kit ! SCORE !The PCB is a blue phenolic impregnated pressed paper type single sided board. THe circuit board has a production date of week 31 1977 while the IC itself was made week 27 of 1977... The venerable 7107 has been around for over 35 years ! and it's still in production and in use in plenty of 3 1/2 digit LED panel metersThe IC socket is not a 'socket' as we know it today but simply a bunch of female pins with no supporting plastic whatsoever soldered into the board.Over the years this board must have been in some funky environment as 'stuff' is growing on the two solid tantalum caps outer body ...The board looks like it was assembled by a 5 year old kid using an oversized soldering pistol... solder is not melted as much as heaped on with a trowel ...I always wondered about the funny segment ordering on these chips but it now all becomes clear ! the pinout was designed to match the MAN7x style LED displays that were prevalent at that time. Not a signal crossing in sight. It's all straight lines !Some components on this board make a person dream... the displays were made by ITAC-Litronix in Mauritius.... who'd have thought there was a 7 segment LED display maker there in the 70's ? Mauritius is in the indian ocean off the coast of madagascar of all places.....The same with the ICL chip. Singapore... What on earth drove the early silicon makers to places like Singapore and Malaysia ? I've always wondered how singapore became such an attractor for semiconductor makers. Intel opened their first plant there in the late 60's !I haven't had the guts to power it up, out of fear of destroying the icl7107. I'm going to restore it a bit first, clean up all the soldering, replace the salt encrusted tantalums, straighten the resistor legs a bit.. and then power it up...

author: peter.mitchell
author_rank: Super Contributor
timestamp: April 08, 2013, 06:33:50 am
content: I'm pretty sure it was because of trade that they put their fabs in singapore, that, and water.

author: notsob
author_rank: Frequent Contributor
timestamp: April 08, 2013, 07:02:00 am
content: It was labour costs (in SG at that time) and political stability. The IC wafers(dies) were produced in the USA, put in a bottle covered in a protective solution and sent offshore, and the wafers were assembled into the DIL package in Singapore or elsewhere..

author: vk6zgo
author_rank: Super Contributor
timestamp: April 08, 2013, 07:36:46 am
content: Pretty agricultural looking for 1977,especially with the "pretend " IC socket!Looks like some of the El Cheapo kits you used to see in the back of magazines back in the day.

author: digsys
author_rank: Unknown
timestamp: April 08, 2013, 10:20:09 am
content: I remember a kit similar to that (maybe it was that one), even used those ceramic LED decoder/drivers - had a quick look,only found the later versions that I still use on an old counter I made that was quite popular. When the price shot upinto the $10s, I replaced it with a plug-in MPU. It was definitely one of my favourites from the past.

author: amyk
author_rank: Super Contributor
timestamp: April 08, 2013, 11:45:42 am
content: I was expecting to see die photos of the '7107...

author: muvideo
author_rank: Frequent Contributor
timestamp: April 09, 2013, 06:28:42 pm
content: Very nice, it's something that could well be exposed in a museum,"the birth of an evergreen classic IC"As for the tantalums, are them wet type? I'm going by memory,but if I'm not mistaken, that should be the effect of sulfuric acid leak...Fabio.

author: steve30
author_rank: Frequent Contributor
timestamp: April 09, 2013, 06:50:12 pm
content: Nice findNever realised the 7107 was so old. 'Tis a handy chip. They are on my shopping list for building some panel meters.

author: steve30
author_rank: Frequent Contributor
timestamp: April 21, 2013, 06:20:57 pm
content: Just wondering, does anyone know what the '7107 was actually designed for? Like, what made them want to design it in the first place?

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 21, 2013, 06:27:31 pm
content: Quote from: steve30 on April 21, 2013, 06:20:57 pmA 3.5 digit LED/LCD driving A/D converter? I think I don't understand your question but here is the datasheet:http://www.intersil.com/content/dam/Intersil/documents/fn30/fn3082.pdf

author: Bored@Work
author_rank: Super Contributor
timestamp: April 21, 2013, 06:47:27 pm
content: Quote from: steve30 on April 21, 2013, 06:20:57 pmThere is some connection with Fluke. The ICL7107's sibling, the ICL7106 or a very similar IC is what made Fluke's first digital handheld multimeter, the 8020A, work in 1977. Fluke claims they designed it, and Fluke only used the internal number 486464 for it in the service manual, but if you compare it with the 7106 you can't help to get the idea they could be the same.

author: SeanB
author_rank: Super Contributor
timestamp: April 21, 2013, 06:59:08 pm
content: I would guess Fluke contracted Intersil to do the single chip 3.5 digit meter design for them, and probably were looking to get a 2 or 3 chip solution ( RCA had one at around the same time which was a 3 chip solution) but Intersil was able to get the system down to a single IC, and kept the rights for it instead of only being the fab. They probably had a contract that gave Fluke a 2-3 year exclusive deal though.

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 21, 2013, 07:07:11 pm
content: Quote from: Bored@Work on April 21, 2013, 06:47:27 pmNow you mention it, this can't be a coincidence...

author: Rufus
author_rank: Super Contributor
timestamp: April 21, 2013, 08:35:38 pm
content: Quote from: SeanB on April 21, 2013, 06:59:08 pmThe Fluke 8020A came out in 1977 the date code of the chip on the board above is 1977.Like it still says in the datasheet today I always thought the design was aimed at digital panel meters. They did (still do) a range of similar display drivers and integrated counters and displays. I think it as if not more likely that Fluke decided the could build a DMM around the part rather than commissioned it. If it really was a Fluke design do you think they would have given the rights to their 'fab' to sell it to competitors to make DMMs?

author: Bored@Work
author_rank: Super Contributor
timestamp: April 22, 2013, 04:26:53 am
content: Fluke says they designed the IC in the 8020A. And that IC happens to look like the ICL7106 ...http://www.fluke.com/Fluke/usen/community/fluke-news-plus/ArticleCategories/RD/Quote

author: casinada
author_rank: Frequent Contributor
timestamp: April 22, 2013, 06:17:43 am
content: The RCA Solution was the pair CA3161 (BCD to 7 segment) and CA3162 (A/D Converter). I remember building a voltmeter using the chips in my teens (70's) and burning a fewthey were expensive. I ruined a few by going over the 5.5V limit on the power supply, they were totally unforgiving. Al the equipment I had was an RCA VOM and a home made power supply.

author: SeanB
author_rank: Super Contributor
timestamp: April 22, 2013, 07:46:43 pm
content: I have a board with those, and the third chip is an intersil ICL7660 to give the required -5V rail so you can have an input that is ground referenced ( very useful) and they are pretty good devices.

author: rsjsouza
author_rank: Super Contributor
timestamp: April 22, 2013, 09:59:44 pm
content: Nice finding, free_electron! I still have two 7107s in working condition (datecode 1988) and they work really great (just like their 7106 sibling). The major drawback is that they need simmetric power supply (the 7106 does not).