clock selecting using 556 and NAND
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I believe the logic is correct with my NAND gate setup. How fast can a CMOS
NAND pulse if I have one input HIGH and the other pulsing? I maybe going to
fast. Also, is my schematic of the 556 correct (the 555 is pictured for
simplicity and doubled in the 556)
50Kvar 1K +5
/\/\/\ _/\/\/\ ___|___
|_____ 4| 8|
1K | _|_|_ _ _
_/\/\/\_|____7 | 555|-3--output_| |_| |_
|________2&6 | |
|-+|(
| 1
1uF |-ground (this was borrowed from Radio Shack's
Engineer's Mini-Notebook, Digital Logic Circuits, page 12)
Thanks again
-Sean
> The 555 (or 556) does indeed output 0-5 volt pulses if you have it connected
>
> properly....they will drive TTL or CMOS gates directly. Don't forget that a
>
> NAND gate outputs a 0 when both inputs are 1. Is this what you want...you
> have to make sure that you want that function. Remember that a positive
> logic
> NAND gate ia a negative logic OR gate. (DeMorgans theorem). You can use a
> pull-up resistor if you want but I don't think that is your problem!
[noparse][[/noparse]Non-text portions of this message have been removed]
NAND pulse if I have one input HIGH and the other pulsing? I maybe going to
fast. Also, is my schematic of the 556 correct (the 555 is pictured for
simplicity and doubled in the 556)
50Kvar 1K +5
/\/\/\ _/\/\/\ ___|___
|_____ 4| 8|
1K | _|_|_ _ _
_/\/\/\_|____7 | 555|-3--output_| |_| |_
|________2&6 | |
|-+|(
| 1
1uF |-ground (this was borrowed from Radio Shack's
Engineer's Mini-Notebook, Digital Logic Circuits, page 12)
Thanks again
-Sean
> The 555 (or 556) does indeed output 0-5 volt pulses if you have it connected
>
> properly....they will drive TTL or CMOS gates directly. Don't forget that a
>
> NAND gate outputs a 0 when both inputs are 1. Is this what you want...you
> have to make sure that you want that function. Remember that a positive
> logic
> NAND gate ia a negative logic OR gate. (DeMorgans theorem). You can use a
> pull-up resistor if you want but I don't think that is your problem!
[noparse][[/noparse]Non-text portions of this message have been removed]