Punched Tape Reader Peripheral for 8008 Emulator

The project was somewhat stymied by other commitments and also by an amazing failure of a simple chip. I was putting the finishing touches on a "confidence test" for the paper tape reader, and suddenly only all '1"'s would read. It turned out that the HC165 used for serialization to the ESP8266 just simply stopped clocking out data right in front of me.  Part of the problem in debugging it was that I simply could not believe it. The failure was in the smaller reader (shown to the left of the 8008 emulator) that I built first - the photo details of the build of the PTR  are actually of the second build,  which was large enough for sockets. The first build was smaller, and because I added in the HC14's later, I did point to point wiring of the two HC14 and HC165 chips, which was very nasty, and potentially impossible to fix.

What I would up doing is cutting out the HC165 up to the plastic body of the chip, putting in a new HC165 with the legs folded in, and soldering the legs of the new chip to what was left of the legs of the old chip. This actually worked! however, I did not replace the 0.01uf decoupling capacitor on top of the chip, and there is a bit of noise causing a misread about every 500 characters.

I suppose that proves that the decoupling capacitors were needed... :)

I'll fix that soon, and when I do, updated code and schematics will be available.

Second Attempt (electronics only): Better, Still Mylar/Black Only

(The photos of internal workings in the gallery are of the second attempt PTR Module)

So, using some lessons from the first build, I built another, using a mask made of  copper PCB material drilled out for the optos. I also considerably thinned the guide slot by using 0.015" PCB material and the double-sided Apple tape. On this unit, this mounts to the LED board, making assembly/modification much easier. After a few weird component issues (an LM117-3.3 putting out 4 volts and a dead opto, easily found with the test tape and program) this worked better. I still made the 1.000 slot for the paper tape a bit too wide; I corrected this with "cat whiskers" on either side of the slot made of resistor trimmings to fine-guide the tape. This worked VERY well, with no "cross-talk" or show-through problems. But....I still can get good reads only from Mylar or black tape. I suspect that I will have to use op-amp comparators or something like that in attempt #3.  Still, this electronics module is a good build and I will probably use it with an 8080 emulator project.