Author Topic: password  (Read 2297 times)

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Offline harpoTopic starter

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password
« on: April 09, 2011, 05:10:54 PM »
hello and thank you for reading this topic

would anyone know how to make a password system were....... well let me just say what i need it to do

first there would be a keypad (USB type)
when the correct 4 digits were entered and the user pressed the key "enter" and let a electrical current pass
kind of like a keypad activated switch.

I am not asking for exact details but i would like a generalization of what to do would be help full as i have not found any things about this topic via Google.

again ty and have a niceday!

Offline Soeren

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Re: password
« Reply #1 on: April 09, 2011, 07:42:32 PM »
Hi,

would anyone know how to make a password system were....... well let me just say what i need it to do

first there would be a keypad (USB type)
Is it for a PC?
If not, why complicate it with USB?

 
when the correct 4 digits were entered and the user pressed the key "enter" and let a electrical current pass
kind of like a keypad activated switch.
Kind of?
Sounds to me like it's exactly what you're talking about. What's unclear to me however, is whether you want to make something for a PC or a stand alone system.


I am not asking for exact details but i would like a generalization of what to do would be help full as i have not found any things about this topic via Google.
Then you haven't spend much time on Google.

First off, define exactly what you wanna do, what hardware it includes, what it should control etc.
Then break it into sub-projects that you can handle a bit at a time.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline harpoTopic starter

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Re: password
« Reply #2 on: April 09, 2011, 08:44:17 PM »
ty for your comment

1: yes a keypad activated switch is what i want to do
2: i said a usb keypad because i already have 1 but i have some money and could a wire per number type of keypad.
3: i will not be using a computer and would hope to not use a microcontroller ( i dont have one)

Offline harpoTopic starter

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Re: password
« Reply #3 on: April 09, 2011, 08:46:36 PM »
also soeren thank you for posting you always seem have somthing good to say

Offline Soeren

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Re: password
« Reply #4 on: April 10, 2011, 10:10:02 AM »
Hi,

i said a usb keypad because i already have 1 but i have some money and could a wire per number type of keypad.
If you are prepared to "ruin" the keyboard, it could probably be used, by accessing each key/switch in the matrix separately, but I would think a "loose" keypad would be quite cheap (and then you keep the USB keypad functional :))
The keyboards with all contacts separate might be the easiest to use, when you don't wanna use a microcontroller, but go for whatever is the cheapest.
(You could even wire up some of the small PCB switches from a discarded VHS or similar, to make your own keypad).


i will not be using a computer and would hope to not use a microcontroller ( i dont have one)
If you have no previous experience with microcontrollers (which would be an easy solution otherwise), discrete logic can be used.
The net is full of circuits for that, but some of them are quite large and you really don't need that much for a basic keypad lock.

There's basically two ways to tap in a code.Either press 1, press 2, press 3, press 4, (press enter if used), or the method where you press all 4 buttons/keys at once and hold them for a short time.
The circuit you'll need depends on that.


The "press all at once" method takes very little circuitry and it doesn't even need logic chips - a few transistors and "glue" (R's and C's etc.) will do.
Each code key goes towards opening the lock after a delay and each non code key stops the delay from ever timing out, so just one wrong key keeps it from opening and if one of the code keys isn't pressed, the delay will never start.

The simplest "1 key at a time" can be made from eg. a 4017 and a 4093 (cheap and common) + glue.
Each output goes to a code key and if pressed a pulse is clocking the 4017 one step forward to the next code key. Any wrong or out of order key resets the circuit.

Decide which type you want to make and then see if you can figure out a way to do it.
If you get stuck, or if anything of the above is unclear, post what you have up to that point and we'll help you along.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline kl22

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Re: password
« Reply #5 on: April 11, 2011, 10:19:14 PM »
Hi,
This might not be of much help. But I worked on a security system for a safe in Uni as a project.

If you are planning to do something that has software installed go with Soeren.

Also, as Soeren mentioned you can get something working using discrete logic. You will need to come up with a state machine, and implement it. The upside is that you will not need any coding, but the downside is you might end up with ALOT of circuitry, if you don't set up your state machine properly.

Offline aruna1

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Re: password
« Reply #6 on: April 16, 2011, 01:00:05 AM »

The simplest "1 key at a time" can be made from eg. a 4017 and a 4093 (cheap and common) + glue.
Each output goes to a code key and if pressed a pulse is clocking the 4017 one step forward to the next code key. Any wrong or out of order key resets the circuit.

Decide which type you want to make and then see if you can figure out a way to do it.
If you get stuck, or if anything of the above is unclear, post what you have up to that point and we'll help you along.


pretty cool method  :)
I'm Me

Offline The arctic wolf

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Re: password
« Reply #7 on: April 18, 2011, 01:01:30 PM »
Hello everyone,
Harpo, please explain what level of security you want to achieve.
If you need only basic level than you can simplify Soerens suggestion and just buy few combinated switches(I mean those that have a normaly open and normaly closed in one switch),
then you just connect them in a row, the switches that part of the password combination you connect as normaly open, all the other switches you connect as normally closed, and walla, you have it.
If you press only the right switches the lock is oppened, if you press any additional switch, it will break the circuit and the lock will remain closed:

        <----/---/----/   /-----/---/-----/   /------/---/-----/   /------->


The downside is that it's easy to override this kind of lock and just short circuit the password panel..
If you need a good security level then I personally recomend a microcontroller based system.

Andrei.