Help! Need Datasheet for CR850T - Page 1
Forum section: electronics / general

author: david77
author_rank: Frequent Contributor
timestamp: September 17, 2010, 06:34:05 am
content: Hi lads and lasses,I'm desperately trying to find a datasheet for an old Signetics OP CR850T. It's in a TO-99 tin can.I've tried the usual web searches but no luck so far.Maybe somebody's got an old Signetics databook lying around and could provide me with the info.Thanks!

author: TheWelly888
author_rank: Frequent Contributor
timestamp: September 19, 2010, 01:52:50 pm
content: Did you try the datasheet thread here? Hopefully one of the sites mentioned will yield what you want.https://www.eevblog.com/forum/index.php?topic=14.0

author: DJPhil
author_rank: Frequent Contributor
timestamp: September 19, 2010, 05:08:26 pm
content: I spent a few hours digging as deep as I could on the internet and found squat, not even a pinout!I'm not even sure what it is, though if it's an opamp it's possible that there's a semi-standard pinout for TO-99s.This one's really got me beat. You might consider asking some ham radio folks, locally or online. They've usually stashed away books for everything, and they often work with older stuff like TO-99s.Sorry I couldn't help.

author: Unknown
author_rank: Unknown
timestamp: September 19, 2010, 06:04:33 pm
content: I was unable to find it in the 1972 Signetics databook (available fromBitsavers. This suggest that is was not current production at that time (either older or newer), or was not a regular catalog item. I don't find any CR (or OP) parts in that databook. If there's a date code stamped on the IC, that might help you find a databook from the correct year.The opamp might not be a bad guess.

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: September 19, 2010, 06:11:13 pm
content: Do you have a bunch of these parts loose, or are you looking at something soldered to a board?If on a board the configuration of the circuit would be very helpful.It -could- be a house numbered part. That is, a manufacturer orders a truck load of some component from a semiconductor company with their own internal part number marked on them. If so they're almost impossible to figure out.I have 3 rails of 16-pin ICs all marked "U43" and a date code.I also have a couple dozen rails of what are most likely a fairly high power audio amp from ST. Unfortunately they are house marked, and I've wasted a LOT of time trying to sort out what they are.

author: david77
author_rank: Frequent Contributor
timestamp: September 20, 2010, 11:59:36 am
content: Hi and thanks for your troubles guys.The device lives in the Fluke meter from the other thread. I've come to the conclusion that it is aspecial Fluke marking, as there is absolutely nothing to find about this device. I have even contactedsome dealers who specialise in end-of-life semiconductors - same answer there.It actually has a standard pin-out like LM308, 741 etc. in TO99 case.I have replaced it with a LM308 in TO-99 case as that was the only "decent" OP Amp in that case Ihad flying around in my OP Amps box.Fluke used it as a chopper in the A/D converter of that meter.The LM308 works fine, but I'd like to have known what was so special about the Signetics device.Then I could even go to the trouble and wire in some better suited replacement in DIP8 package.But what the hell...it works. That's the important thing.@JohnS_AZ: I know all about unknown IC's. I have rails and rails of stuff nobody knows a thing about...

author: Unknown
author_rank: Unknown
timestamp: September 20, 2010, 03:37:55 pm
content: The only option in that case may be Fluke reference material. I assume the service manual of the meter didn't contain any helpful info (like selected LMxxx)? I'm not aware that Fluke has anything similar to HP/Tektronix semiconductor cross-reference guides, but who knows. If you haven't tried yet, you could try asking them. Not sure how helpful they are for old equipment and how much documentation they still have available, but it's worth a try.

author: david77
author_rank: Frequent Contributor
timestamp: September 20, 2010, 05:02:30 pm
content: Nope, no reference to any LMxxx in the manual. I wouldn't have needed to ask then.Hm, I might just ask them. German Fluke have been more than helpful regarding very oldequipment. They once sent me a copy of the really old 8120A bench meter manual free of charge.The good brands are usually quite helpful in that respect. Hameg once sent me circuit diagrams of a 50 yearold oscilloscope. These sorts of companies still give a shit about customer service, unlike the cheapo stufffrom China where it is even luxury to get a translated manual.