Hey there.... Any one here know how to assemble an electronic keypad (with pin) to work like an SPST switch (wire to mobo header for pow on) ????? possible keypad: http://www.maplin.co.uk/products/module.asp?CartID=030124193206679&moduleno=2538&modulecode= but any circuits one can come up with will be appreciated!!! Thanks, Mike.... Linear and Macro Can you do this?
(linear and Macro) What about me!!! You need a keypad encoder if you want it to work properly. I bought one from Allelectronics.com http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=EDE-1144&type=store -------------------- All the keypad is, is a matrix of switches. You could use a circuit that uses Latching gates to make the code you want work.
Actually, If you wanted it to "Look" like it worked, you could have just one of the numbers connected like a spst momentary switch, and then just press a bunch of numbers in, saving the "real" key for last....It would seem daunting, but be pretty easy to get around, I would think... Another way is to hook up like 4 numbers in series, and you would have to have all 4 down at the same time to work it.... "Macro.." "Linear..." "ZAP...." "Howabout ME????"
if you wanted you could lookaround here (or electonics forum) and try to find the circuit that makes a momentary switch behave like an spst. Make x amount of them and wire them up in series and that would allow it to turn on if the correct buttons are pressed(in any order, theres a little more wiring to do it in one order) then wire all of the rest up to an "always on" version of the same thing. If a wrong key is pressed the "always on" would go off and the circuit would need to be reset somehow before you could continue. Im not sure how to do that, but another momentary (puch to break instead of the push to make of the others) switch hoooked up to whatever you decide to power the curcuit with, (MB standby cuircuit?) the interruption should reset it. IE if the sequence was 1234, the numbers 1,2,3 and 4 would have this "push to make --> spst converter circuit" on it and be hooked up in series. As long as only 123 and 4 are pushed the computer will power up. the rest of the numbers would be hooked to one "puch to make --> spst converter circuit" that turns off when you push it, and that is in series with the others. if 5,6,7,8,9,0 are pressed the circuit wont work. the last thing you need is a reset curcuit that cuts the power, momentarily (push to break), running the "converter circuits" once that is done you can try again to enter your code. There is probably a way to do this with a a whole bunch less stuff, but im not a guru and Im just working on functional units I have seen around here.
There's two parts to this. First, interfacing logic level to the power switch headers. I've successfully used a 4066 (there are a few variants of this chip) to interface. Problem solved, $0.50 at the very most. Second, you need a circuit that will output HIGH only when you poke the buttons in the right sequence. That's a classic digital design problem (by which I mean it's probably in every textbook, and I definitely had to solve it on at least one exam/quiz). To tackle the second part, you need to define the problem a lot more specifically. You need to establish the length of the key sequence, figure out and specify whether you can clear partial entries, develop a state diagram and all the crap that makes digital design fun. Seriously, I'm not gonna even touch it unless you can come up with a problem statement that is complete enough, and that includes how many keys are on the pad, how long the code is, whether you allow a clear button, and a few other details like is the code hardwired or should there be a function to change it, and how is that implemented, and then is there a backdoor override code, and all kinds of fun. (ZW, the encoder is cool, but why have him use serial comms?)
Like Zap said, use latches... Say now you used a 4 button code, The first correct code trips the latch, so that power can get to the second latch, then when that one's pressed it sends power to the next latch, and so on... all you have to do is set each other key as the "reset" for the first latch, so if the wrong key is pressed the circuit is resetted.
See though, you're letting your implementation drive your design. That ain't how it's supposed to work. Forget about how to do it until he clarifies what he's doing. Otherwise, you get to the 35th revision of the scematic before a requirement surfaces and the whole implementation is rendered useless.
true true... I've considered an automatic/ovveridable fanbus using a Basic Stamp or an OOPIC and was thinking of implementing a keypad, but then I realised why.. win2k is passworded anyway! I even considered incorporating a SitePlayer into it so I could control it via the net and serial port...
Woah, you guys know what yer on about hehe.... Well, basically a 10digit pin is cool and a basic 4x3 (like what I showed keypad) is enough. Of course a nicer keypad is cool..... clear partial entries: if possible, yea...what if I make a mistake in input? hehe.. how about a few 7-segment LED's to display stuff like: 'Access Denied' or 'Access Granted' and stuff like that? hardwired code is kinda lame, so being able to change it (via dip switches if anything else is harder) no probs would be nice... all help is greatly appreciated! Thanks, Mike... P.S. Sorry ZAP, I forgot you! LOL...yea whups....okay your included for sure... HAHAH
Power Source ------------------ Given that THIS will control the powering on of the PC, it will need an independant souirce of power, so I was thinking a 12vdc rechargable battery that could 'trickle' charge when the PC is on... Of course, if the code is entered WHILE the PC is on....nothing much will happen...but hrm..it's a loophole.....hrm Mike....
Um... Why don't you just run it off the 5V from the PSU that is ALWAYS on unless you unplug it... That's how the startup switch on an ATX Peecee works anyways... All you have to do is use the 5V, and that is the logic level of choice for the circuitry you are talking about anyways... Otherwise, you will have to drive a relay to power on the 120 and then momentarily close the startup switch to start the thing... Either way, if they get into your pc, it won't matter, Just short the power switch header with a screwdriver for a second and it's started... It would LOOK cool and high-tech though...
Um 5V in on the molex plug is it not? or we talking about a different 5V? Ahh I always wondered how it 'new' to start interesting...good idea... but now I need circuits and stuff.... Come on zap!!!!
That would be correct... The purple wire is the standby 5V for powering the WOL, On switch, Bios clock (To keep from running the cmos battery down) etc.
