Re: TI-H: 0.1 capticitor


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Re: TI-H: 0.1 capticitor



On Tue, 10 Dec 1996 17:58:57 -0500 (EST), you wrote:
>On Tue, 10 Dec 1996, A.K.A. TheWiz wrote:
>
>> > >I have been wondering for months where to find a smaller cap, and I
>> > >recently realised that something that small may actually overclock the
>> > >TI-85.  If you wan those speeds, just take out c9 and leave it empty.
>> > If one was to do this, then the wave being sent to the Z80 would be
>> > totally flat, and would have no pulse in order to regulate it's internal
>> > clock.  Therefore, the Z80 would freeze, and possibly be ruined.
>>   No, this is one method (the simplest) of turboing the TI.  It works.
>> But can anyone tell me _why_?  I don't understand analog circuits very
>> well...
>
>I would have to guess that it is the capacitance of the wires still there.
>By the way, that is DEFINETLY not 20-40 pf.  I would guess closer to 
>.00001 pf.

Uhh, there's no such thing as a 0.00001pf capacitance.  Even with a
relatively large resistance in the network, that would add up to a
clock frequency of a couple hundred *gigahertz*, which obviously
doesn't happen.  In reality the smallest capacitance possible anywhere
in a circuit is around 0.5-1pf, and even that's pretty small.

What we're dealing with here is the input capacitance (the capacitance
that naturally occurs in the CMOS gating of the chip), which is
probably a couple hundred pf.

-Mel


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