How to connect two wires?

Sometimes, to test the imagination and the presence of substandard thinking, the subjects are asked a question. How much do you know how to connect the two wires? Prepare handkerchiefs to wipe away bloody tears. I will talk about my once realized project on the way to the search for truth.

So, 13 years ago ...

Access system - start

At the enterprise where I worked, there was no normal throughput system. It was the usual sovok system. Those who worked in the factories will understand me. The employee approached the checkpoint, pressed the button with his number, which was associated with the pusher. The pin pushed the pass to the guard and he gave it to the employee, after having first checked the face with the photo. As he left, the pass gave up.
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I wanted to change something. Funding is not, and the craving for beauty is in the blood. So I learned that the LPT port can be curbed. Yes, in those days we were still clinging printers to such connectors. RFID, i-Button? No, then did not hear / did not see / can not afford.

Pass
Ordered plastic rectangles, the size and thickness of the standard familiar to all. And cut them into the grooves in various combinations.



Receiver

Made a box with a slot. Six micro-ends were placed in the slot. Five pins were responsible for encoding cards. The sixth pin (in the picture rightmost) was needed to determine the presence of the card in the card reader.



Program and scheme of work

Unfortunately, I was unable to start the exe program, it gives errors. Although the source code is preserved. The program listened to LPT port. As soon as the sixth pin was locked in the card reader, a unique card code consisting of 1 and 0 was immediately read. After that, the resulting code (for example, 00010) was compared with the database. In the case of a successful search, a signal was sent to the control LED. The card can be removed. When you exit the procedure was repeated. In general, there were two control LEDs. Thus, we have used all available data lines from LPT. When reading the cards, the security guard on the monitor appeared a pop-up message with information about the employee. The time of passage of each employee through the guard post was written to the database. It was possible to build simple reports on tardiness.

Access system - end

The system worked for about 2 months quite stably. It all ended in regret and not through the fault of self-made development. The guards began to put games on the computer and upload movies, viruses, to while away the long nights. After a specified time, the computer began to die from immense debris. We cleaned the system, instructed the guards. This event was enough for a week. Bearded men were constantly changing. Admin then we did not have free computers, too. Dust and dirt at the post, the guards, a dead computer without proper maintenance signed a verdict to this access system. And we abandoned her. But as you know, the end of something - always the beginning of something new.

Conclusion

Now we can afford to buy a biometric throughput system. Finger - pass. Not to mention the legendary i-Button or popular RFID cards. Looking through my memory of my attempts, to do something new for myself, to discover something unknown, I involuntarily smile. To study outdated protocols, study dead programming languages ​​or reinvent the wheel - each of us decides for himself the need for such an evolution of knowledge acquisition.

And how many ways do you know how to connect two wires? Soldering, twisting and screw clamps are not offered.

UPD I liked the method proposed by IZh

Make the ends of the wires flat, rest against each other, and wait a few years. Diffusion of metals will do the trick. There was no time limit, it seems.