CD datasheet, CD pdf, CD data sheet, datasheet, data sheet, pdf, Intersil, CMOS OR Gate. CD – Dual 4-In OR Gate. Item #CD $ $ The CD is supplied in a 14 lead outline package: Features a Thru-Hole Device. Data Sheet. Texas Instruments cd Logic Gates are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas Instruments cd Logic.

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Imagine that you sit on cd40772 PC desk, you pull the keyboard, the mouse is near by, you click the button and the computer boots.

Now imagine the same scene, but instead of pushing just a button, you enter the datsaheet code! That was one of my imaginations when i was a kid. Nowadays, i could make a more complex systems, with security code, LCD display and hardware key, but i decided to make a more simple yet secure circuit for the other ‘kids’ that want to boot with more than just a cold pushbutton. There are more simple dztasheet less secure circuits. This circuit has a 4-digit security code that is hardware selectable.

It can have as many ‘wrong’ digits as you like, but up to 4 ‘correct’ digits.

CD4072 Datasheet

Also, one digit cannot be more than once in the security code. Suppose for example that you choose to cd402 10 digit keypad with numbers datasheey 0 to 9. One code could be the numberor thebut the code is wrong! The digit ‘4’ is more than once in the code and that cannot happen.

Each ‘correct’ key press will SET a flip-flop. Whenever a ‘wrong’ button is pressed, all 4 flip-flops will be RESET and the code must be entered again from the beginning. Also, if the code must be entered in the correct order. The keypad can have as many keys as you like. The 4 D inputs are the ‘correct’ buttons.

Each one must go to one and only key! For example, someone could connect the D1 to key number 4, the D2 to key number 2, the D3 to key number 9 and D4 to key number 5.

CD4072 Dual 4-input OR Gate

The code to open the lock would be ”. All the other buttons that will reset the circuit must be connected to the ‘ERR’ input. So if the keypad had 10 keys and the code was ” the keys xatasheet and 0 must be connected to the ERR input.


The keys can be a push-button with one normal-open contact, connected to the positive VDD of the circuit. Look at the following PCB layout:. The circuit is designed to operate at any voltage between 5 and 15 volts.

The only thing that needs to be changed is the relay. If you will use normal push-buttons for the keypad, i suggest you cd44072 the following circuit instead.

This is exactly the same circuit as the previous one, with the only difference on the reset. Instead, it uses diodes connected as OR gates. It has the same operation as the previous one, but it is dagasheet recommended to be used with a touch keypad! This circuit is significantly simpler and equally secure to the previous one. It needs a smaller PCB an one chip less. The circuit on a breadboard for test.

This circuit has the CD Chip included and can be used with touch keypad as well. To be more secure, the keypad should be on another remote PCB. The keypad could be normal pushbuttons. A nice print-out with some kind datashfet artwork and holes that correspond to the keypad PCB-keys, can mask the keypad and make it more elegance. This circuit does not have the chip.

CD 데이터시트(PDF) – Intersil Corporation

It has the same functionality, it is simpler, but it cannot be used with touch keypads. Here is a video from the circuit in operation! You are welcome to comment for corrections and suggestions on this page.

But if you have questions please use datashedt forum instead to post it.

At 31 May7: At 14 November1: At 28 July7: After testing this circuit on breadboard, I found that it would not reset after pressing the correct key-codes. May be an auto-reset feature should be added? I referred some resources and found that it can be done by a timer and some parts. Based on your circuit, I made another version which also include the feature mentioned above and the “disable the keypad when green LED lights” enables again after 5 seconds. At 3 October At 3 September It will require to spend a lot of time to design and test the PCB.


At 2 September Actually one of my Ic’s Pin was broken. But now its working perfect Anyways thanx for ur time and help Thanx in advance At 25 August I opened a forum thread for you to follow. Please continue this conversation there because it may become a long thread: At 23 August Or the reset line has a problem. Which circuit are you using? The one with the or with the diodes? At 22 August What should I do???

Plz help me its Ergent: At 1 June0: Is this design able to expand to accommodate a seven digit code? At 19 June So, No, it would not work. Suppose now that the code is The R is LOW.

When no key is pressed, the S is also LOW from the pull down resistor. From the truth table, Dstasheet and S-0 makes no change to the outputs. Now you press the digit 4 first. Look what happens at the truth table in this situation. When you leave the 4th digit, everything returns to LOW.

Did i solve your problem? At 19 June9: At 18 June You are talking about the first or the second circuit? At 21 May You mean you cannot see it clear? Click on it and it will maximize. Most of dayasheet images will maximize on click.

Look the video and read the section “The keypad”. It is easy, At 1 March3: At 24 January Thanx At 15 January Then you will connect the RESET of this new flip flop to the output of the pin 1, that is the reset signal from an error button. I have not test it but it could work. Test it and post the results. At 15 January How to do it? At 29 December6: I kept it as simple as possible.

At 29 December5: U mean,all other button except the 4 code button should daatsheet connected to ERR? Simple is nice Kammenos,rather than programming a microcontroller. At 28 December ,