Advice 1: How to make a copy of the key for the intercom at home

Using Arduino you can make at home a copy of the key, and the intercom 15 minutes, if, for example, the workshop closed and the key is needed urgently. Let's see how it's done.
Make a copy of the key for the intercom using Arduino
You will need
  • - Arduino;
  • computer;
  • - key for the intercom type iButton or 1-wire;
  • key blank to create a "clone" of the original key;
  • - 1 resistor of 2.2 kOhm;
  • - connecting wires.
Each key for the intercom has its own room - this room serves as a key identifier. It was on the room key intercom solves your or someone else's. Therefore, the copy algorithm like this: first you need to know the number of "permitted" key and then assign this number to another key - clone. To intercom there is no difference, was applied to the original key or its copy. Checking the number against its database of allowed numbers, he opened the door.
Keys for intercom, which we will connect to Arduino (sometimes called iButton or Touch Memory), is read and written via the 1-wire interface 1-wire. Therefore, the connection scheme is very simple. We need a couple of wires and a pull-up resistor of 2.2 kOhm. The scheme shown in the figure.
Connect the key for the intercom to Arduino
To work with 1-wire interface there are ready-made library for the Arduino. You can use like this: Download the archive and extract the folder "libraries" folder of Arduino IDE. Now we can simply run the Protocol.
Download Arduino the standard way the sketch shown in the illustration.
The sketch read the key number from the intercom
This sketch shows the key number for the intercom that is connected to the circuit. This is what we need now - we need to know the key number, a copy of which want to do. Connect the Arduino to the computer. Start monitor serial port: Tools -> Monitor serial port (or keyboard shortcut Ctrl + Shift + M).
Now connect the key to the scheme. The port monitor will show the key number. Remember this room.
Know the key number, which clone do we do
Now rewrite the sketch so that he could record the data in the key memory. Code given in the illustration. In the code given detailed comments. Most importantly, do not forget to specify the number of your original key in the array key_to_writethat you learned earlier.
The sketch to program the iButton key
Upload this sketch to Arduino. Open the monitor serial port. Connect to the schema key to be a clone of the original key. The result of programming the serial port monitor will display an appropriate message.
1) If when you compile a sketch, an error will occur [ WConstants.h: No such file or directory #include "WConstants.h" ], it should be in the file "OneWire.cpp" replace the first block after the comments on the following:

#include "OneWire.h"
#include "Arduino.h"
extern "C" {
#include "avr/io.h"
#include "pins_arduino.h"

2) If while compiling you get error "class OneWire has no member named read_bytes" or similar, then find another library OneWire, the Internet is a lot of them.
Keys for intercom come in different types and families. This code will not work for all keys, but only for RW1990 or RW1990.2. The programming key may result in key risks.
Given the desire, it is possible to rewrite the program for different type of key. For this you need to find a description for Your key (datasheet) and correct the code of the sketch according to the description.

Advice 2: How to make hard cheese at home

Cottage cheese to cook is not difficult, and although it consumed a lot of milk, the result always pleases fans. However, in order to prepare cheese at home, you will have to get pressure, otherwise you will not be able to remove excess fluid.
How to make hard cheese at home
You will need
    • press;
    • form cheese;
    • a large clay pot;
    • the colander;
    • a long knife;
    • 8 bricks;
    • 2 large piece of cheesecloth;
    • 2 cups fresh milk (to ferment);
    • 4.5 l of cow's milk;
    • 4 tbsp. butter;
    • 3/4 tsp of baking soda;
    • 2/3 Cup of sour cream;
    • 1/4 tsp salt.
Make the starter: Express 2 cups milk at room temperature for a day.
Add yeast to 4.5 liters of warm milk, cover the container with a lid and leave in a warm place for 12 hours.
Place the container with the curdled milk into a large, filled with warm water. Put them on a small fire, use a thermometer to monitor the heating water should heat water to 38оС for 30-40 minutes and maintain this temperature until the mass reaches a sufficient density.
Determine the moment when the mass can be cut with a knife, cut the curd with a long knife into cubes 3 by 3 cm, right in the pot, then with a long spoon and mix them up, trying not to mash and to prevent the sticking of the cubes. Check out the pieces on density: gently squeeze your fingers and quickly release. If the piece is easy to break into pieces, does not stick to hands, it is possible to end heating (usually heat lasts from 40 to 60 minutes).
Drain the whey using a colander, line a rimmed gauze form for cheeseand (any container with holes in the bottom), put the cheese mass. The ends of the cheesecloth tie the top, place the mold under the press. Put on the upper Board press 4 bricks, then add one brick every ten minutes, giving freely to drain the serum. In conclusion, leave the ground under the weight of 8 bricks per hour.
Remove the mass from the mold, add the butter and baking soda, chop them with a knife in small pieces to mix well with butter and soda. Put in a clay pot, tightly clutching a weight to the bottom, leave in a warm place for 2.5 hours.
Add the weight of the sour cream and salt, stir. Put in the form of heat (smaller capacity with cheeseom more full of warm water). Put on a slow fire, stir until the solid compounds of sour cream with mass. Then pour the mixture into the pot, greased, and put in the cold. Observe cheese for 2-3 months.
Is the advice useful?