More VSS

[jdzura at csc.com]

Bruce,

OK, on to phase 2,   As I understand things to use the schematic from
yesterday, I would need the following.
1)  7486
2)  7474
1)  DS-C304A      What is this part, and what does it do?.
1)  7805
2)  100 Mfd. Caps.    One in and out of the 7805 to stop oscillations?.

The caps will probably work fine. Usually, 1 uF at the input and 10 uF at the
output are adequate. Also, good practice usually places a 0.1 uF at the output in
parallel with the 10 uF.
The DS-C304 is a ttl output Crystal oscillator. Nearly any frequency will do, but
the slower the better. The frequency of the oscillator defines the width of the
pulse coming out of the Xor gate. At 100 MPH, the VSS freq should be 2*100*2000,
or 400KHz  right?  As long as the oscillator is 500 KHz or above you should be OK.
I'm pretty sure Digikey has 1 MHz XO43 Style oscillators.


For the divide by 2, just one 7474, the 7805, and 2 caps, right?.
Correct!
It is usually good practice to include a 0.1 uF cap right at the power leads of
each IC. It provides for local power for fast switching and cuts down on radiated
noise from the logic part.

Let me know if you have any problems / questions.

Joe D