Translating some electronic circuitry symbols.

The topic of my project is the internet’s effect on security. I am focusing on implementations that rely on “security via obscurity” and how with the rise of the internet, not only is there no technology who’s back end is not exposed to some degree, but there is probably a web community dedicated to probing it.

The part I am stumped on is the climax of my presentation, a magnetic stripe card emulator. While there is a lot of talk about them online, coming across one that can do more than temporarily emulate one card, is difficult.

My demonstration involves a “brute-force” type of emulator. The closest thing I can find is this diagram:

**broken link removed**

The documentation is sparse at best, further this is my first foray in to electronic circuitry of any real complexity. The solenoid will transfer the pulses from the microprocessor to the magnetic head in a card reader I am building.

The hardware consists of a microprocessor, a PIC16C84, generating pulses controlling the magnetic flux in a solenoid, and some switches and capacitors to control the PIC as well as some transistors to amplify the current to drive the solenoid.

Here is a key I wrote for the symbols. I need to make a parts list, and come up with a working breadboard. Are my interpretations correct?:

**broken link removed**

Are my interpretations correct?

Looks pretty good.

The crystal oscillator may in fact be just a crystal - but have a look at the data sheet for the pic processor to determine this.

The non polarised cap may in fact be polarised but not shown as such - if it is more than about 1uF it will probably be polarised with positive at the top.

The PIC16C84 is even more obsolete than the PIC16F84 which was obsolete at the end of the last century. Look to the PIC16F628A as the modern pin compatible replacement.

The symbol you have noted as a crystal oscillator, is just a crystal.
The circuitry to make the "oscillator" part is in the PIC.

JimB

Thanks!

First, thanks so much! To all of you!

I changed the symbol I had noted as a crystal oscillator, to just a crystal.

Ok, the PIC16C84 is obsolete, Papabravo said the PIC16F628A is a compatible replacement. Well **broken link removed** work on the PIC16F628A as well?

Now the 5 resistors, one is labeled 15 Ohm and one 100 Ohm any suggestions for the Ohm of the other 3?

As for what dch222 said, about the capacitor probably being polarized, (if it is more than about 1uF). Should it be? I think 1uF is a measurement of the capacitance of the capacitor it self, and as the only reference to it is the symbol in the diagram, what should I base that on?

Received as a PM from Rhino1:

Rhino1 said:

Thanks for pointing that out...
First, thanks so much! To all of you!

I changed the symbol I had noted as a crystal oscillator, to just a crystal.

Ok, the PIC16C84 is obsolete, Papabravo said the PIC16F628A is a compatible replacement. Well **broken link removed**work on the PIC16F628A as well?

Now the 5 resistors, one is labeled 15 Ohm and one 100 Ohm any suggestions for the Ohm of the other 3?

As for what dch222 said, about the capacitor probably being polarized, (if it is more than about 1uF). Should it be? I think 1uF is a measurement of the capacitance capacitor it self, and as the only reference to it is the symbol in the diagram, what should I base that on?

Click to expand...

Capacitors.
Depending on many factors a 1uF capacitor can be quite large (and expensive) if it is not an electrolytic (polarised) type.
Experience suggests that a 1uF electrolytic type would be most suitable.

Resistors.
The resistor connected to the reset switch, about 10k ohm should be OK.
The other two connected to the H-bridge circuit, I will leave that to other to decide.

JimB