Showing posts with label keypad. Show all posts
Showing posts with label keypad. Show all posts
Thursday, November 20, 2014
A 4 Digit Keypad Controller Switch Circuit
This is a universal version of the Four-Digit Alarm Keypad . I have modified the design to free up the relay contacts. This allows the circuit to operate as a general-purpose switch. It also means that it can be used to control all of my Alarm Circuits. Ive used a SPCO/SPDT relay - but you can use a multi-pole relay if you wish.
The relay is energized by pressing a single key. Choose the key you want to use - and connect it to terminal "E". Choose the four keys you want to use to de-energize the relay - and connect them to "A B C & D". Wire the common to R1 and all the remaining keys to "F".
The Circuit is easy to use. When you press "E" - current through D2 & R9 turns Q6 on - and energizes the relay. The two transistors - Q5 & Q6 - form a "Complementary Latch". So - when you release the key - the relay will remain energized.
To de-energize the relay - you need to press keys "A B C & D" in the right order. When you do so - pin 10 of the IC goes high - and it turns Q4 on through R8. Q4 connects the base of Q6 to ground. This unlatches the complementary pair - and the relay drops out.
Any keys not wired to "A B C D & E" are connected to the base of Q3 by R7. Whenever one of these "Wrong" keys is pressed - Q3 takes pin 1 low and the code entry sequence fails. If "C" or "D" is pressed out of sequence - Q1 or Q2 will also take pin 1 low - with the same result. If you make a mistake while entering the code - simply start again.
The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7 or 8 terminals will NOT do. With a 12-key pad - over 10 000 different codes are available. If you need a more secure code - use a bigger keypad with more "Wrong" keys wired to "F". A 16-key pad gives over 40 000 different codes.
The relay is energized by pressing a single key. Choose the key you want to use - and connect it to terminal "E". Choose the four keys you want to use to de-energize the relay - and connect them to "A B C & D". Wire the common to R1 and all the remaining keys to "F".
The Circuit is easy to use. When you press "E" - current through D2 & R9 turns Q6 on - and energizes the relay. The two transistors - Q5 & Q6 - form a "Complementary Latch". So - when you release the key - the relay will remain energized.
To de-energize the relay - you need to press keys "A B C & D" in the right order. When you do so - pin 10 of the IC goes high - and it turns Q4 on through R8. Q4 connects the base of Q6 to ground. This unlatches the complementary pair - and the relay drops out.
Any keys not wired to "A B C D & E" are connected to the base of Q3 by R7. Whenever one of these "Wrong" keys is pressed - Q3 takes pin 1 low and the code entry sequence fails. If "C" or "D" is pressed out of sequence - Q1 or Q2 will also take pin 1 low - with the same result. If you make a mistake while entering the code - simply start again.
The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7 or 8 terminals will NOT do. With a 12-key pad - over 10 000 different codes are available. If you need a more secure code - use a bigger keypad with more "Wrong" keys wired to "F". A 16-key pad gives over 40 000 different codes.
Tuesday, August 12, 2014
5 Digit Alarm Control keypad Wiring diagram Schematic
This Simple 5 Digit Alarm Control keypad Circuit Diagram switch will suit the Modular Burglar Alarm schema.However, it also has other applications. The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with7 terminals will NOT do. Choose the five keys you want as your code, and connect them to `A, B, C, D & E`.
5 Digit Alarm Control keypad Circuit Diagram
Wire the common to R1 and all the remaining keys to `F`. Because your choice can include the non-numeric symbols, almost 100 000different codes are available. The Alarm is set using the first four of your five chosen keys. When `A, B, C & D` are press edin the right order and within the time set by C1 and R2 (about10 seconds), current through R11 switches Q6 on. The relay energizes, and then holds itself on by providing base current forQ6 through R12.
The 12-volt output switches from the “off” to the “set ” terminal, and the LED lights. To switch the Alarm off again it is necessary to press A, B, C, D & E in the right order. The IC is a quad 2-input AND gate, a Cmos 4081.These gates only produce a high output when both inputs are high.Pressing `A` takes pin 1 high for a period of time set by C1 andR2. This `enables` gate 1, so that when `B` is pressed, the output at pin 3 will go high. This output does tw1o jobs. It locks itself high using R3 and it enables gate 2 by taking pin 5high.
The remaining gates operate in the same way, each locking itself on through a resistor and enabling its successor. If the correct code is entered within the time allowed, pin 10 will switch Q5 on and so connect the base of Q6 to ground. This causesQ6 to switch off and the relay to drop out. Any keys not wired to `A, B, C, D or E ` are connected to the base of Q4 byR9. Whenever one of these `wrong` keys is pressed, Q4 takes pin 1low. This removes the `enable` from gate 1, and the code entry process fails. If C, D or E is pressed out of sequence, Q1, Q2 orQ3 will also take pin 1 low, with the same result.
You can change the code by altering the keypad connections. If you make a mistake entering the code, just start again. If you need a more secure code you can use a bigger keypad with more `wrong`keys wired to `F`. A 16-key pad gives over half a million different codes. All components are shown lying flat on the board; but some are actually mounted upright. The links are bare copper wires on the component side. tw1o of the links must befitted before the IC.
5 Digit Alarm Control keypad Circuit Diagram
Wire the common to R1 and all the remaining keys to `F`. Because your choice can include the non-numeric symbols, almost 100 000different codes are available. The Alarm is set using the first four of your five chosen keys. When `A, B, C & D` are press edin the right order and within the time set by C1 and R2 (about10 seconds), current through R11 switches Q6 on. The relay energizes, and then holds itself on by providing base current forQ6 through R12.
The 12-volt output switches from the “off” to the “set ” terminal, and the LED lights. To switch the Alarm off again it is necessary to press A, B, C, D & E in the right order. The IC is a quad 2-input AND gate, a Cmos 4081.These gates only produce a high output when both inputs are high.Pressing `A` takes pin 1 high for a period of time set by C1 andR2. This `enables` gate 1, so that when `B` is pressed, the output at pin 3 will go high. This output does tw1o jobs. It locks itself high using R3 and it enables gate 2 by taking pin 5high.
The remaining gates operate in the same way, each locking itself on through a resistor and enabling its successor. If the correct code is entered within the time allowed, pin 10 will switch Q5 on and so connect the base of Q6 to ground. This causesQ6 to switch off and the relay to drop out. Any keys not wired to `A, B, C, D or E ` are connected to the base of Q4 byR9. Whenever one of these `wrong` keys is pressed, Q4 takes pin 1low. This removes the `enable` from gate 1, and the code entry process fails. If C, D or E is pressed out of sequence, Q1, Q2 orQ3 will also take pin 1 low, with the same result.
You can change the code by altering the keypad connections. If you make a mistake entering the code, just start again. If you need a more secure code you can use a bigger keypad with more `wrong`keys wired to `F`. A 16-key pad gives over half a million different codes. All components are shown lying flat on the board; but some are actually mounted upright. The links are bare copper wires on the component side. tw1o of the links must befitted before the IC.
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