Bob, Are you 100% sure that there is no marking? I have seen devices with laser = marking that were so feint that the only way to make them appear was to use= white baby powder rubbed on the top, and then powerful light at a very low= angle. Just my $0.02, Jean-Paul AC9GH > On Dec 7, 2015, at 1:41 PM, Bob Blick wrote: >=20 > On Mon, Dec 7, 2015, at 10:35 AM, Byron Jeff wrote: >=20 >> Bob, >>=20 >> My thought process is trying to track down the chip is a fools errand >> just >> because there are so many chips that fit the description. >>=20 >> Is it possible to do a black box approach? Essentially there are only 6 >> pins to decode. Figure out which are inputs and outputs. Then use a logi= c >> analyzer to grab the functional operation of the device.=20 >>=20 >> At that point figure out if a PIC can mimic that operation. If so, then >> it >> really doesn't matter what the original chip was since its functionality >> was captured. >>=20 >> I hope I didn't miss some obvious flaw to this approach. >>=20 >> BAJ >=20 > Hi Byron, >=20 > I pretty much figured out what it's doing. One pin sends pulses to the > LED, another monitors the phototransistor, another drives the motor. The > discretes are for buffering and the phototransistor amp. I'm not sure > what the comparator chip does, perhaps they don't trust the > microcontroller's brownout detector.=20 >=20 > What really caught my interest is why there are no markings on the chip. > It seems very strange. The operation is so simple there wouldn't be any > reason to try to obscure the part number. >=20 > Best regards, Bob >=20 > --=20 > http://www.fastmail.com - Faster than the air-speed velocity of an > unladen european swallow >=20 > --=20 > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .