"Dan Hollands" wrote in message
...
"Henry" wrote in message
om...
I am tinkering with some 25 year old TTL logic chips and I need to make a
de-bounce circuit that will stay on for the duration of a the
push-button.
I
have several ways already to debounce the button close, but they are
one-shot pulses that have thein own duration. I need both the close and
open
of the push button to be debounced and it to keep the duration of the
button
push. I have seen schmitt trigger circuits (that I have tried to build
but
dont seem to work (have to triple check the wiring)), and other RC
variations. What kind of easily accessible parts (like from Radio Shack)
should I be looking for. It all has to run on 4-AA batteries. Looked an
some
op-amp parts at RS but they seem to all require 18v, or more, supply.

BTW, the debouncing solution needs to be acurate to within about 1
milli-second.

Henry




The easiest way is to use a pushbutton with Form C contact (single pole,
double throw) connected to 2 cross connected NOR gates so that when the
moving contact hits one pole connected to one NOR gate the cross
connection
latches in one state and when the moving contact hits the other pose
connected to the other NOR gate the cross connection latches in the other
state. Thus you get a latch circuit the follows the pushbutton with no
glitches.

If you don't know how to implement this let me I can give you more details

Dan


Thanks, but I have no control over the push button. Its a camera shutter.
Might be mechanical, might be electronic. Either way it acts like a simple
push button closing a circuit. The mechanical ones, of course have noise.

I have an old camera that I want to try some specialy effects photography
with. I also have a view camera that has a focal plane leaf shutter (built
into the lens) that, in theory, should sync with a flash through its range
of shutter speeds (up to 1/250 of a second.)

Anyway, thanks. I will keep looking.

Henry