Post by thread:[EE]: Identifying pins on unknown 7-segment LED

A friend (?) has given me a bag of about a 100 seven-segment LED's which he said he found while cleaning out his workshop. He doesn't know what they are and says that they probably date back to the mid 1980's sometime. :-( I'd like to be able to use them in miscellaneous projects if I can identify which pins are which. I can try trial and error, since there are a lot of them, but thought I would take a chance and see if someone on this list might be able to point me to a datasheet, or something like that. They are 3/4" high by 3/8" wide, red in color. They are in the shape of a 14-pin IC. Looking into the face, there are two indentations at the bottom and a single indentation at the top, with a dimple at the top left (probably to identify pin 1). Assuming this is pin 1, then there is a pin 1, 2, 3 and 4. No pin 5. Pin 6 and 7. Continuing to the othe side, there is pin 8, 9, 10. No pin 11, no pin 12. Pins 13 and 14. There is absolutely no marking of any sort to indicate the manufacturer or the model number. (I have examined it with a magnifying glass under a strong light). Thanks for any help. John -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

On Thursday 10 April 2003 09:41 am, John Nall wrote: > A friend (?) has given me a bag of about a 100 seven-segment LED's > which he said he found while cleaning out his workshop. He doesn't > know what they are and says that they probably date back to the mid > 1980's sometime. :-( > > I'd like to be able to use them in miscellaneous projects if I can > identify which pins are which. I can try trial and error, since > there are a lot of them, but thought I would take a chance and see > if someone on this list might be able to point me to a datasheet, > or something like that. > > They are 3/4" high by 3/8" wide, red in color. They are in the > shape of a 14-pin IC. Looking into the face, there are two > indentations at the bottom and a single indentation at the top, > with a dimple at the top left (probably to identify pin 1). > Assuming this is pin 1, then there is a pin 1, 2, 3 and 4. No pin > 5. Pin 6 and 7. Continuing to the othe side, there is pin 8, 9, > 10. No pin 11, no pin 12. Pins 13 and 14. Does this help? Remember that it could be either common anode or common cathode... http://www.iguanalabs.com/7segment.htm -- Ned Konz http://bike-nomad.com GPG key ID: BEEA7EFE -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

Hi John First, try places like agilent.com and books/CD's like RS Electronics and Farnell. You might just find a generic. Your pin out sounds familiar (ie: I've seen it before). or: If you can test an LED, you can figure out the pinouts quickly (without destroying one). A multimeter set on diode test or ohms will pass a low voltage through the LED and most of the time, you will see the LED come on (glow). Play around until you get an LED segment to come on, then decide which pin is common (C or A) then you can go through all the pins to figure out the segments. Since you got 11 pins, that gives you 7 segments +DP, +common=9. Most likely the two remaining pins are also common or N/C. Hope this helps. Quentin -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> I'd like to be able to use them in miscellaneous projects if I can > identify which pins are which. I can try trial and error, since there > are a lot of them, but thought I would take a chance and see > if someone > on this list might be able to point me to a datasheet, or > something like > that. Just 'crush' one, there is probably a PCB like thingy inside, from which you can find the common and segment pins. Now you only have to try for CC or CA. And anyway, even without looking inside trial-and-error takes only a minute or two. Just done that on a 3.5 digit display in 5 minutes. Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

> I'd like to be able to use them in miscellaneous projects if I can > identify which pins are which. I can try trial and error, since there > are a lot of them, That should be very easy to do, however. Probe around with 12VAC and 1Kohm in series. You shouldn't be able to do any damage with that. The AC will light up LEDs regardless of direction. Short one side of pins together connected to one AC side, then probe individual pins with the other. You should be able to find the common anode or cathode in well under a minute. Once you've got that, switch to DC to figure out which, then just pins to segments. This really shouldn't take more than a couple of minutes. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

On Thu, Apr 10, 2003 at 12:41:11PM -0400, John Nall wrote: > A friend (?) has given me a bag of about a 100 seven-segment LED's which > They are 3/4" high by 3/8" wide, red in color. They are in the shape of > a 14-pin IC. Looking into the face, there are two indentations at the > bottom and a single indentation at the top, with a dimple at the top > left (probably to identify pin 1). Assuming this is pin 1, then there > is a pin 1, 2, 3 and 4. No pin 5. Pin 6 and 7. Continuing to the othe > side, there is pin 8, 9, 10. No pin 11, no pin 12. Pins 13 and 14. > > There is absolutely no marking of any sort to indicate the manufacturer > or the model number. (I have examined it with a magnifying glass under > a strong light). John, It takes less that two minutes to ID all of the pins. All you need is a DC power supply and a current limiting resistor. Make sure that the resistor won't pass more than 10ma of current when dropping the whole voltage of the supply. So for 5V use 5V/0.1 -> 500 ohms (470 is fine). This will light the LED but protty much guarantees that it won't blow out an LED no matter the current rating. Create a probe by tying the resistor to the V+ lead of the supply, and a lead to the GND. Take one end and tie to pin 1. Drag the other across all the other pins. If any segment lights up then you have a starting point. If not then move the fixed end from pin 1 to the next pin. Generally within 30 seconds you'll get a segment to light up. If the floating end of the probe lights up any other segment, then the fixed end is the common. Otherwise the floating end is the common and you start IDing with the fixed end. In any case you can completely ID the entire display in about 2 to 3 minutes. I never both keeping pinouts on LED displays because they are so easy to ID. BAJ -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

It takes less that two minutes to ID all of the pins. All you need is a DC power supply and a current limiting resistor. My initial thought was that this sounded like a TIL311 (hexadecimal display with internal logic. But the missing pins are in the wrong place.) The sort of tests being propose will NOT work on that sort of device (of course, "that sort of device" is pretty rare...) BillW -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email @spam@listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

At 02:51 PM 4/10/2003 -0700, BillW wrote: > It takes less that two minutes to ID all of the pins. All you need is > a DC > power supply and a current limiting resistor. > >My initial thought was that this sounded like a TIL311 (hexadecimal display >with internal logic. But the missing pins are in the wrong place.) The >sort of tests being propose will NOT work on that sort of device (of course, >"that sort of device" is pretty rare...) > >BillW Actually, the proposed tests did work OK, once I got over the shame and embarrassment of not realizing that I could do that BEFORE asking for help. :-) The device does not have a common anode (nor a common cathode) but instead has THREE common anodes! (Of course, these can easily be made into a common anode). The led itself, embedded (like unto a reporter) in the chip is a tiny little thing, possibly having some historical value to people who are interested in the development of 7-segment displays. The fellow who gave them to me said that he originally bought them from a person named "Bill Godbout" (I am not sure if this was an actual person, or the name of a company) who got them surplus from somewhere. At any rate, I have gunned them out, and once again proclaim the value of Internet communication (with all its warts). John -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email KILLspamlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> instead has THREE common anodes! (Of course, these can easily be made into > a common anode). The led itself, embedded (like unto a reporter) in the Does this mean that the display is viewable almost solely from one side only, distorts what you see, fails to display almost anything viewed from the other side, provides views with an interesting perspective, can't be relied on for accurate data, .... ? :-) RM (I think I may yet regret this one :-( ). -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

The fellow who gave them to me said that he originally bought them from a person named "Bill Godbout" (I am not sure if this was an actual person, or the name of a company) who got them surplus from somewhere. Heh. Both. Bill Godbout ran "Godbout electronics", an early heavy player in the S-100 CPM computer world. Bought a bunch of stuff from him a long time ago, and never quite got it working :-( (not his fault...) I wonder if my S100 "system" is still sitting in storage over at Stanford somewhere? A web search turns up lots of early history. Apparently Godbout become CompuPro, and did generic surplus before focusing on computers... BillW -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestspamBeGonemitvma.mit.edu>

John wrote: > The device does not have a common anode (nor a common cathode) but > instead has THREE common anodes! Each anode has 2-3 separate cathodes, I assume? If so, I see some interesting possibilities here - you could drive one of these things with 1/3 multiplexing using 4 PIC pins and 3 resistors, that's MUCH nicer than standard 7-segment LEDs. Jason Harper -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestEraseMEspam_OUTmitvma.mit.edu>

At 03:48 PM 4/11/2003 +1200, Russell wrote: > > instead has THREE common anodes! (Of course, these can easily be made >into > > a common anode). The led itself, embedded (like unto a reporter) in the > >Does this mean that the display is viewable almost solely from one side >only, distorts what you see, fails to display almost anything viewed from >the other side, provides views with an interesting perspective, can't be >relied on for accurate data, .... ? :-) > >(I think I may yet regret this one :-( ). Most likely you will. It did provide a chuckle, however. :-) And around these parts, we wonder if anyone thought through just how much alike "embedded" and "in bed with" sound? John -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu>