sequential circuit design

I am having trouble drawing up a state diagram or state table for a
sequential circuit for something I am designing.

In = 1, Out = 0
In = 0, Out = 1
In = 0, Out = 0

I got this far, from refering back to a text book on logic and design:
1/0 0/1 0/0
A ---> B ---> C ---> D
where each letter is a state which occurs because the previous input
was what was needed....After this I am stuck.
How are you suppose to map unwanted states, refer them all back to A
cause the sequence isn't correct.

I was thinking using an edge triggered flip-flop, but then I got
stuck....

I was also considering a SR latch, where the output is feedback to the
reset line, but I needed some way to increase the propagation time, so
that it doesn't reset in a few nano seconds and the solenoid has time
to act.

I needed to pulse a solenoid to close a valve after a trigger had been
activated, because the valve didn't have a spring return
I could do it using a microcontroller, but if I could implement it with
a sequential circuit it would be better....

 

[John Fields]

On 30 Jul 2005 11:15:35 -0700, Balaclavabob@hotmail.com wrote:

I am having trouble drawing up a state diagram or state table for a
sequential circuit for something I am designing.

In = 1, Out = 0
In = 0, Out = 1
In = 0, Out = 0

I got this far, from refering back to a text book on logic and design:
1/0 0/1 0/0
A ---> B ---> C ---> D
where each letter is a state which occurs because the previous input
was what was needed....After this I am stuck.
How are you suppose to map unwanted states, refer them all back to A
cause the sequence isn't correct.

I was thinking using an edge triggered flip-flop, but then I got
stuck....

I was also considering a SR latch, where the output is feedback to the
reset line, but I needed some way to increase the propagation time, so
that it doesn't reset in a few nano seconds and the solenoid has time
to act.

I needed to pulse a solenoid to close a valve after a trigger had been
activated, because the valve didn't have a spring return
I could do it using a microcontroller, but if I could implement it with
a sequential circuit it would be better....

---
You can do it easily with a 7555, like this: ( View with a
fixed-pitch font like Courier New)

Vcc--+---------+-------+---------+--------------+-------+
| | | | |K |
| | | | [DIODE] [COIL]
[10K] [10K] [Rt] | | |
| | | +-----+-----+ +-------+
IN>--+-[0.1ľF]-+-------|--O|TR Vcc | |
| |_ | D
+--O|D OUT|------G
| | | S
+---|TH GND | |
| +-----+-----+ |
[Ct] | |
| | |
GND>-------------------+---------+--------------+

_____ ___ ...___
IN |____________ ...__| |_____

____ ____
OUT_____| |_______ ...______ ...___| |

-->| |<-- 1.1 RtCt


--
John Fields
Professional Circuit Designer