Re: Mockingboard Schematic in GIF form

[mjmahon@aol.com (Michael J. Mahon)]

Hans Otten wrote:

>I have used in the past the following circuit to make a PHI2 signal out of
>PHI1,
>with a RC circuit and a schmittrigger (which also adds to the delay)
>delevering
>the wanted delay and inverting.
>
>                                         74LS14 
>PHI 1  --- 270 ohm --------------|> --------- PHI2 of 6522
>                                  |
>                                 = 82 pf
>                                  |
>                                GND
>
>This works because:
>- PHI2 is the inverse of PHI1
>- PHI2 is shifted  about 15-75 ns to PHI1
>
>Comparing the real PHI2 with the generated PHI2 with an oscilloscope showed
>me
>it was close enough.  

This is a fine way to generate a pseudo-PHI2 signal, also done
with an approximately 22ns RC integrator.

-michael

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