Old Transistor Array P/N Suggestions?

Discussion in 'General Electronics Chat' started by OldSkoolEffects, Oct 17, 2013.

  1. OldSkoolEffects

    Thread Starter Member

    Nov 18, 2009
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    I'm in a weird situation. I'm trying to reverse engineer a circuit in order to duplicate it. It's all analog and wire wrapped, but I can't figure out what one of the chips is (qty 2), as far as a part number is concerned.

    The parts (2) in question are transistor arrays, but 24 pin wide DIP packages.

    I've built later versions of the same circuit, but in that instance, three ULN2004s were used instead of two of the larger chip.

    Both the older circuit I am trying to replicate and the one I've already built are driving 6V incandescent lamps. If it matters, there are 22ohm 1/2W carbon composition resistors in the unknown circuit, one for each lamp, but I don't know if they are being used as a sink on the transistor, or for current limiting on the lamps themselves.

    Any suggestions are welcome. Please remember that I realize I can make this circuit with modern components, but that's not what I am attempting to do.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    There is not much top go on, no Numbers? What Country of Origin is the equipment?
    There were quite a few PLA, programmable logic arrays used that were 24pin used in similar applications, if this were the case you could be out of luck?
    Max.
     
  3. OldSkoolEffects

    Thread Starter Member

    Nov 18, 2009
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    I have no P/Ns for the 2 chips in question. The circuit is a pair of 4015s timed by a 4047 to run 16 lamps. I don't believe they were programmable chips; I think they are just off-the-shelf transistor arrays, but the size and number of pins has stumped me. It's essentially a circuit I've already built before with 3 ULN2004s instead of two of these unknown ones.

    These unknown parts should have been readily available in the early 1980's in the US. Unfortunately, the few reference photos I have of this circuit are low-res, and the chips have non-OEM labels over the middle, so I can't even seen if they are solid or something like an EEPROM.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    What is the reason to clone it rather than duplicate it with modern components?
    I assume you won't be wire wrapping?
    BTW the ULN2803 has one more output over the 2004's.
    Max.
     
  5. Meixner

    Member

    Sep 26, 2011
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    Sorry, I dont mean any offense but Im not quite sure what your question is. Are you trying to identify these chips? or find a replacement? I can tell you that back in the late 70's and 80's National Semiconductor had a large line of chips like that, drivers in wide packages. but it would be hard to determine without a schematic of your circuit.
     
  6. OldSkoolEffects

    Thread Starter Member

    Nov 18, 2009
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    I'm going to be wire wrapping (I did it with the later version of the circuit with 2004s).

    I am trying to replicate the circuit in question with the original parts. It's easy to build the things with modern parts, but that's not the point here. Hell, if I really wanted to, I'd just use a PIC, but that isn't the point of this exercise.

    I'm simply trying to identify a chip that fits these guidelines:

    -Available in the USA and the 1980s
    -24 pin WIDE DIP
    -Transistor Array (similar to ULN2004 internally)
    -Drives (16) 6V lamps

    I don't see how a schematic would help in this case; all I'd have is my 4015/4047 system with air-wires going into a blob called "unknown transistors."
     
  7. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    With 24 pins, you can not buffer 16 lamps.
    The chip sounds more like an 4 to 16 decoder (only one lamp will be lit at a time).
    The 74159 TTL chip is something like that.

    Bertus
     
  8. PackratKing

    Well-Known Member

    Jul 13, 2008
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    For what good it does, can you put up a pic of the mystery arrays ??
     
  9. ScottWang

    Moderator

    Aug 23, 2012
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    1. Can you attach a photo of that product and typing the ID number on the photo.
    2. What's the function of the product? (describe it as a list)
    3. Drawing a block diagrams of the product.
    4. How is the voltage of +Vcc?
     
    Last edited: Oct 18, 2013
  10. OldSkoolEffects

    Thread Starter Member

    Nov 18, 2009
    68
    1
    [​IMG]

    This is as good an image I can post. It's been clipped from a larger image I'm not at liberty to distribute, but the resolution is the same. The 2 chips on the left are 4015s (being timed with a 4047). The large ones are the ones I am trying to identify. The labels on them say "high blue" and "low blue" and are only there to signify which is driving what portion of the lamps. The circuit in question was originally powered by 12V lantern batteries.

    Given the way my current circuit (with 3x uln2004s) is wired, these chips should be able to power 16x 6V lamps from a 5-12V source. That's an assumption, though.

    Considering the fact that this circuit and my current working circuit should be nearly identical, and by all appearances use the same chips EXCEPT for the transistor arrays, I'm making the logical assumption that the large chips in question are also transistors arrays, but of a different type. The lamps have a common +VCC, and the transistors are providing a ground switch.
     
  11. ScottWang

    Moderator

    Aug 23, 2012
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    >high blue" and "low blue
    I think they are "high byte" and "low byte", so they could be the EPROMs, they has programs or datas in inside.
     
  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Could be EEPROMS. An EEPROM clocked by a binary counter can provide PWM, and have different PWM patterns in its ROM.

    Do you have a reason for not peeling off the paper labels and reading the IC part numbers?
     
  13. Meixner

    Member

    Sep 26, 2011
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    Sorry, what I meant was a pinout of the unidentifed IC's.
     
  14. bertus

    Administrator

    Apr 5, 2008
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  15. ScottWang

    Moderator

    Aug 23, 2012
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    Because we don't know the Date of manufacture, but if the material of IC was made of ceramic then they could be the EPROMs, if they made of plastics then they could be the PROMs or ROMs or EEPROMs.
     
  16. OldSkoolEffects

    Thread Starter Member

    Nov 18, 2009
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    I don't have that board in hand to peel off stickers (it's under lock and key about 2000 miles away), or I would have the entire picture and wouldn't be here.

    I know they say "High Blue" and "Low Blue" because of the nature of the lamps they are driving.

    Every other circuit from this group has been completely analog, with no programming whatsoever, so I find it hard to believe they would use EEPROM for those two chips while retaining all other chips for timing and such. It's all 4047, 4015, 4017, and ULN2004 (on every circuit but this one).
     
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
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    We could go from LSI's of the time to PAL's etc.
    It seems apparent that with the information provided so far, there are so many possibilities that any suggestion is going to be purely guess work, and even with the right guess, it is impossible to confirm it!
    Max.
     
  18. ScottWang

    Moderator

    Aug 23, 2012
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    The memory as EEPROM, they are not necessary to be the program inside, they could be the datas, you can using them to generating the datas of sine wave and send them to the DAC, and then they became the sine wave generator.
     
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