A DIY card reader, FYA

Mike Stein mhs.stein at gmail.com
Wed May 6 12:52:26 CDT 2015

This grew out of off-list correspondence about the
card punch I'd mentioned on here recently; I
thought it might amuse some folks or just possibly
even be interesting:

----- Original Message -----

> On Tue, May 5, 2015 at 10:11 PM, Mike Stein
> <mhs.stein at gmail.com> wrote:
>  I've got a crazy idea; are you handy
> mechanically and electronically?
>  I've got a couple of mag card readers; I think
> it would be a most awesome kludge to turn one
> into a punched card reader ;-)
>  On the other hand, one of my PPT readers also
> reads EPCs (Edge Punched cards)...
>  m


> From: Kyle Owen
> To: Mike Stein
> Sent: Wednesday, May 06, 2015 11:23 AM
> Subject: Re: Fw: Wright card punch
> Hey Mike,
> I'm certainly more handy when it comes to
> electronics than mechanics, though I've dabbled
> in a bit of everything it feels like.
> What kind of mag card readers do you have? And I
> assume PPT is punched paper tape? I guess I
> haven't seen too many EPCs in my time. What were
> they used for?
> Kyle


Hi Kyle,

I wasn't entirely serious about the mag card
readers, but it's not a totally ridiculous idea

They're sort of like a linear floppy disk: Imagine
a credit card reader like the one at your local
ATM that sucks in the card and spits it out, but
the card is the size and shape of an 80 column
punched card but made from more or less the same
material as a floppy disk.

The tracks are straight and lengthwise instead of
concentric and they're read the same way as your
credit card, with a stepper mechanism to select a
specific track across the width (height?) of the
card either under computer control or manually
(note the < and > buttons on the front).

Remove the track-select stepper mechanism, add a
light source and an array of 12 photo sensors (or
a mechanical contact of some sort) and you've got
a one-at-a-time card reader; it's even already got
a couple of photo sensors ;-)

As usual with the old stuff (and most of the
'real' punched card readers) the feed rollers look
a little rough, although it looks like you could
probably make new ones out of wood or plastic and
just put a rubber band around them.

Pity I'm getting rid of the punch or I might
actually try it myself for a lark.

EPCs are really just punched cards of various
sizes but instead of using the whole area of the
card the data is punched along the bottom edge
just like paper tape; they're usually read by
normal PPT readers that have a special guide for
the card.

Pictures of the mag card reader here:


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