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 Post subject: chips/switches
PostPosted: 23.01.2003 02:55 
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Regular Modder
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Joined: 24.10.2002 23:16
Posts: 241
Location: California
what kind of chip would i need to make my scroll lock key into an on/off switch and how would it need to be wired?


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 Post subject:
PostPosted: 24.01.2003 00:11 
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Mini Modder
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Joined: 11.12.2002 07:24
Posts: 80
Location: USA: Michigan
If you know some of this. I appoligize in advance. I have a tendacy to give too much detail at times.

it somewhat depends on the keyboard. Computer electronics have three forms (ok, 3 forms ingnoring TTL vs ISO standards) of logic. Which need a bit of background first...

Electronics have what is known as a clock. All the clock does is jump up 5v then down to 0v (zero volts) very quickly over and over. Other devices need this to know when to be triggered.

Type 1.) Level edge triggered divice: Rare. Don't worry about it. It means that the device hooked to the clock can be triggerd when either juping up to 5v or down to zero. Not used in computers anymore, at least not where we can mod them. We'll forget about this.

Type 2.) Negitive Edge Trigger: Device is only triggered when the clock jumps down to zero volts.

Type 3.) Positive edge trigger: Device is only triggered when the clock jumps up to 5v.

Now, this is why it is important to know which. If it is positive edge trigger device (This is the most likely, so make note...) in order for your caps lock to be turned on, you can flip the switch like normal on and it should turn on the capslock on because the circut is looking for that jump up to 5v. But if you go to flick it down to turn it off, you will discover that it won't turn your capslock off! That is because it is looking for a second jump to 5v to turn it off again.

Vise versa for negitive edge trigger.

Now, This is the most important part. Mechanical switches are typically not what is called "bounceless." This means that because the connection relys on two peices of metal joining, which may not maintain a constant connection, causing your capslock to flip on and off several times on one flick of the switch.

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It's quite possible that most/all switches made these days are bounceless. But I really don't know.

As for hooking up, it's just a matter of soldering the leads of the bounceless switch to either side of the contact for the normal buttons.

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 Post subject:
PostPosted: 24.01.2003 05:35 
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Regular Modder
Regular Modder

Joined: 24.10.2002 23:16
Posts: 241
Location: California
ok, lemme state it a litte differently. i want to make a normal momentary switch (is in, the device it controls stays on only while you hold the switch/button in the on position) into an on/off switch. please keep it simple. all i know is that it needs o be a flip-flop switch and it has to be a 74?? or 74???.


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