Flasher problems....

**care2much** · 31-03-2003, 06:23 PM

Hey guys, I have a little problem:

I made my own dejan flasher but I had a spare 74*04 and I used it instead of the 74*14 .

Is there anything I should worry about and, more important, is this the reason for the Rolis flasher gives me the message(or smthng like it) : "Preinitialisation failed . check phone type, wires ..." ?

Please help me ...

**care2much** · 31-03-2003, 06:25 PM

I posted it here 'cause I tried it on a 5110.

**adrianpopa** · 01-04-2003, 04:36 PM

The 74*14 is a hex inverting Schmitt trigger and the 74*04 is Hex inverter .

The difference? The Schmitt trigger is a comparator which switches the output negative when the input passes upward through a positive reference voltage. It then uses negative feedback to prevent switching back to the other state until the input passes through a lower threshold voltage, stabilizing the switching against rapid triggering by noise as it passes the trigger point.
So , yes you can expect problems when reading or writing.

**lonegunman** · 01-04-2003, 10:38 PM

Where did you learn that?

**care2much** · 02-04-2003, 10:27 AM

I really know the difference between the 14 and the 04 (thanks a lot) 'cause I am a 4th year student in Computer Science (Hardware) but I was wondering if is there a reason for the 14 to be there ...

The Nokia is (probablly) 100% digital CMOS or TTL tech so one should not worry 'bout signals not being instable...

^this is for Adrian (by the way are you from TM ?)

My parallel port has an 3.98V high level value what the f*** is the matter??

I measured some other ports on different computers and the level is still under 4V --- I say a "little" low for a TTL/CMOS level
I managed to do something with an ISA controller (4.8v high level)
but is not mine...

**adrianpopa** · 02-04-2003, 02:15 PM

@ care2much
I posted the info so you can see the differnces between the two parts. (I see u dont need it) No need to get angry, cause i'm not trying to patronise anybody.Just trying to help. Or maybe u dont care to much.

(P.S. I'm from TR)