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'[EE] ID an IC from a real Black Box'
I literally have a Black Box, see:
http://www.pacificsites.com/~brooke/BlkBox.shtml and have just finished
drawing a schematic for it using ExpressSCH (by Express PCB). There's a
mystery 16 pin SOIC that has had it's top painted white and hand
lettering of "12" larger letters and "298" smaller letters applied. The
"12" is the number engraved on the metal box (the only marking except
for a bar code label. I think the "298" is the ID for a pseudo random
code used for the spread spectrum transmission. The on-off modulating
signal comes from this mystery IC. The IC also blinks an LED. I don't
think it's a microprocessor because there are a couple of MC4060s and an
MC4051 all used to process a 26.868 kHz crystal down to a 5 second
transmit, 5 second pause signal that could have been put into a micro
controller. The date codes are for years near 1990.
Since all the other chips are Motorola is there a Motorola (or maybe
not) IC that could be powered from a 9 Volt battery on pin 3 and has
ground on pin 11. It must have an internal high speed clock.
Schematic available via email, color image of PCB via CD-ROM.
Thanks for any help,
Brooke Clarke, N6GCE
w/o Java www.pacificsites.com/~brooke/PRC68COM.shtml
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