This Instructable is about a hack of an audio cassette-player and a credit card swiper.

Things you will need:

card reader for magnet cards, it's around 5-15 €/$
some cards obviously, i bought 20 cards for 5 €/$
an old(or new) cassette recorder.
some cables, audio plugs, and the usual solder suspects.

Step 1: CARD READER - WHATS NOT NEEDED

When you open the card reader, there is a PCB in it, that takes one side of it.

And there is a read/write-head on the other side of the slot.

First unplug the head, and take the PCB out, as it's not needed.

The only thing needed is the connector soldered to the PCB. What i did is i cut the PCB around the connector, and grounded all SMD resistors/parts down to zero, to make sure nothing is connected by chance.

See the photos fo more information.

Step 2: TAPE HEAD - CONNECTOR

As you can see on the photos, there are 8 Pins on the head and the connector.

The two pins on the outside are ground pins, you can see on the photo of the tapehead how the ground forms a loop from one of the outside pins to the other.

So thats where to solder the first cable.

Next you can see, also on the tapeheads back side, that there are three pairs of pins, connected to three tape heads. That means that we could write on three lines, which is great for what i plan for this in the future (gate/CV sequencer/sampler).

I chose the middle playhead for the test and wired that up too.

You can choose any one of those, even a pair if you got a stereo cassette recorder.

Step 3: CASSETTE RECORDER

The last step is to open up the cassette recorder.

In my case its a micro cassette recorder, sadly mono, but with a built in microphone, and running on 3V.

Next, find the three solder points on the head, desolder it, and resolder the wires of the swipers tapehead.

Connect ground to ground. Thats the solderpoint thats connected to metal of the head itself.

Wire up the other two wires as you like.

That's basically it.

To test it, press record on the tapemachine, and swipe a card through the reader.

Then play <<play>> and swipe it again.

voilà!

Step 4: INPUT/OUTPUT CONNECTIONS

As a useful extension to the basic test setup, you can solder cables and plugs to the ins and outs of the cassette player to connect it to whatever you want to sample.

Have fun!

For me this was a test for a 3 channel CV/GATE sampler for modular, so stay tuned :)