Greg gave me a ULN2803A peripheral driver IC which is capable of sinking 500 mA per pin, which is more than ample for lighting an LED. I modified my "logic probe" circuit, and now everything is working nicely. As a side-benefit, I now have 8 inputs rather than just 6.
A picture:
Now the 74hc163 properly rolls over from 1111 (15) to 0 (0000). Next experiment - cascading two 74hc163's to make an 8-bit counter.
1 comment:
Good problem solving. Thanks for sharing the process. I too have found the ULN2803 (& similar) work nicely when placed on the outputs of digital ICs that just can't seem to source enough current. Keep up the good work and thanks for sharing.
-EschatologicalEngineer-
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