3 Dec
2006
3 Dec
'06
3:56 p.m.
David Griffith wrote:
Incidentally, I am pretty sure the 'special' ICs in this design are
nothing more than selected 555 timers (they're used as schmitt
triggers).
Sidenote: how hard would it be to make a paper
tape reader and punch from
scratch? The idea is to have a lightweight unit for playing with my
SBC6120 and perhaps Altair reissue/clone (if and when I get one).
Back in the Altair days, there was a company called Oliver Audio Engineering
that made a small optical papertape reader for hobbyist use. You pulled the tape through manually. The read strobe was generated
by sensing the sprocket
holes. It would not be difficult to recreate this device, or something
similar.
An optical paper tape reader should be fairly easy to make. I would
suggest running the tape between rollers (maybe raid parts from a VCR or
something) and take a strobe pulse from a phototransistor on the sprocket
track, rather than using sprocket feed.
I think you'd need a machine shop and considerable skill to make a punch from
scratch, While it would not be beyond the capabilities of those folks who build
clocks and engines from scratch, you're best bet is to try to pick up one on
The other problem is getting a reasonable life out of it. A good model
engineer could make a set of punch pins and a die block, but could he
harden them and then grind them to size again? It's one thing to make a
punch that will punch a few feet of tape, quite another to make a machine
that can be ysed for serious work.
-tony