1. The original circuit diagram with two relays, two switches and a light bulb is shown below
2. Use the "and gate" symbol, which can be drawn as shown in the figure below;
Note that the sign with the door not only replaces the two series relays, but also implies that the relays above are connected to the power supply, and that two relays are grounded.
3. The bulb glows only when the switch above is closed with the switch below. This is the reason for calling it "with the door";
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Repeat the previous article with the door introduction
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4. The input to the door does not necessarily have to be connected to the switch, and the output is not necessarily connected to the lamp. What we really want to deal with is the voltage at the input and the voltage at the output;
5. If we turn the low-level head-up to 0, the high power head is 1, then the relationship between the input and output of the gate is as follows;
6. As with the two switches in series, the relationship between the input and output of the gate can also be described in the following table
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Point out, what we really want to deal with is the voltage at the input and the voltage at the output end.
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7. The same can be used to have multiple inputs to the door. For example, the three relays are connected in series, as shown in
The bulb glows only when all three switches are closed.
is not very detailed, continue to be divided into an article, the content of bad digestion is more fine, if still do not understand is their basic knowledge is not sufficient, such as high and low level
Code-hidden in the language behind the computer soft and hard the 11th chapter of the Janitor 2