Almost OT: Pushbutton switch latching
cclist at sydex.com
Sun Dec 9 01:50:29 CST 2007
On 9 Dec 2007 at 0:15, der Mouse wrote:
> Nice idea, but it doesn't work. Draw out three NANDs cross-coupled as
> you described. Mark the logic states for a stable state with one
> output low. Now consider what happens when each of the inputs goes
> low. The only one that does anything is the one feeding the gate whose
> output is low.
Yeah -- I see that. Release a button and the circuit goes into an
unstable state. I wonder what the smallest number of active devices
is for an n-stable circult with n greater than 2.
8 D flip=flops with each switch connected to a PRESET input and a
NAND (or NOR) to edge-clock in a reset state looks to be far from the
minimum. How about some capacitively coupled logic with a few
More information about the cctalk