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alarm keypad - enhanced 4 digit

2016-02-18 15:13  
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This article describes the enhanced four alarm keypad circuit. For your better understanding in the diagram, we recommend that you look at the text. Works as follows: the keyboard to the kind of common terminal and a separate connection for each key. In a 12-key pad, look for 13 terminals. Matrix type with 7 terminals will not do. The alarm setting press a key. Select the key you want to use, and line "E". Select the keys you want to use four off the alarm when they are connected to the "one BC & D '. Your code can contain non-numeric symbols with a 12-key pad, over 10 000 different codes are available. line common to all remaining R1 and F keys, when pressed "E", the current through the switch Q5 in D2 and R9. energises the relay, and has its own by providing a base current of Q5 through R10. 12 volt output Using from "Off" to "Settings" terminal and LED lights. related and necessary at the time clock A, B, C and D are in the correct order. IC is a four 2-input AND gate, a Cmos  4081 . these gates only produces a high output when both inputs are high. Pin 1 is R5 aloft This "make" gate 1, so when 'A' is pressed, the output at pin 3 will be high and this output and tw1o Jobs It locks itself high using it so that the door 2 R2 and through pin 5 high. remaining gates operate in different ways, each lock itself through a resistor to the successor. If you enter the correct code, the pin 10 in the fourth quarter of the switch, so the connection base ground. Q5 Q5 off and this causes the relay drop out. not connected to any key 'a BCD and E' is connected to the base of Q3 R7. Whenever these "error" key is pressed in the third quarter off a low need this to delete the "Enable" from the door 1, code entry process fails if the 'C' or 'D' in order of precedence, Q1 or Q2 will also brought off a low, same result. You Connect the keyboard can be changed by changing the code. If you need more security code to use a larger keyboard and more "wrong" key to connect to "F". a 16-key pad gives over 40 000 different codes. tw1o The link must be installed in the integrated circuit, all components are shown lying flat on the board, but some people actually installed upright. This link is a bare copper wire and component side. understand the principle that text, you can plug a high efficiency.

Kpad 4dig enhanced 4 digit alarm keypad