Continuous Logic Conversion

[Daragoth]

Hi, I'm somewhat of a beginner to circuit design and have a question.
I have a digital device that generates a logic '1' signal when a
switch is flipped on and goes back to '0' when flipped off. I'm
trying to figure out how to alter the circuit so that when the switch
is flipped on for longer than 2/60th to 3/60th of a second it changes
back to logic '0' regardless of the position of the switch. What
would be necessary to accomplish this? I was thinking perhaps a
counter and a clock, but I'm not too sure. I appreciate any help in
the matter, thanks.

 

[Ian Stirling]

Daragoth <daragoth@kuririnmail.com> wrote:

Hi, I'm somewhat of a beginner to circuit design and have a question.
I have a digital device that generates a logic '1' signal when a
switch is flipped on and goes back to '0' when flipped off. I'm
trying to figure out how to alter the circuit so that when the switch
is flipped on for longer than 2/60th to 3/60th of a second it changes
back to logic '0' regardless of the position of the switch. What
would be necessary to accomplish this? I was thinking perhaps a
counter and a clock, but I'm not too sure. I appreciate any help in
the matter, thanks.

Nonretriggerable monostable.
Search TIs website for TTL chips, and you'll find the appropriate part.

 

[John Fields]

On 13 Dec 2003 01:49:18 -0800, daragoth@kuririnmail.com (Daragoth)
wrote:

Hi, I'm somewhat of a beginner to circuit design and have a question.
I have a digital device that generates a logic '1' signal when a
switch is flipped on and goes back to '0' when flipped off. I'm
trying to figure out how to alter the circuit so that when the switch
is flipped on for longer than 2/60th to 3/60th of a second it changes
back to logic '0' regardless of the position of the switch. What
would be necessary to accomplish this? I was thinking perhaps a
counter and a clock, but I'm not too sure. I appreciate any help in
the matter, thanks.

---
Sounds like all you need is a one-shot with a period of 50ms which is
started when the switch goes ON. If you need to be able to have the
output go OFF if the switch is turned OFF before the one-shot times out,
then connect the output of the switch and the output from the oneshot to
the inputs of a 2-input AND and take your output from the output of the
AND.

--
John Fields