Re: Ladder diagram to CMOS logic

On Oct 28, 6:16 am, John Fields <jfie...@xxxxxxxxxxxxxxxxxxxxx> wrote:
On Mon, 27 Oct 2008 14:50:03 -0700 (PDT), Allen Bong





<allenbsf6...@xxxxxxxxx> wrote:
Hi group,

                              +12v
                               |
               NC              |
               | |,       .-.  |
  IN -+--------,-´-------( X )-+
      |       ´| |        '-'  |
      |                        |
      |   | |NO       .-----.  |
      +---| |--+------|     |--+
      |   | |  |      '-----'  |
      |        |       RELAY   |
      |    T   |               |
      |   ---  |               |
      +---o o--+               |
                               |
                               |
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)

I have the above ladder diagram consisting a relay, a buzzer and a
push button switch.

I would like to sound the buzzer "x" when the input is low and when
the button is pressed the relay would be switched on and holds itself
through the "NO" contact and the buzzer is switched off due to the
"NC" contact is opened.  Both the NO and NC contacts belong to the
same relay.  When the input goes high, the relay releases and the
circuit goes back to normal waiting for the next alarm.

I would like to convert this into a circuit using cmos chips.  I use
an AND and inverters and a 4013 FF and came out with the circuit
below.

                                           VCC
             VCC                            +
             .-.                            |
ALARM=L      | |10K                      ..-----.
NORM=H       | |                         |     |BUZZER
             '-'                         '-----'
IN|\          |   _4081                     |
 -| >O---+-------|  \        __4081         |
  |/     |    |  |   )------|  \    ___   |/
         |    +--|__/       |   )--|___|--|      VCC
         |    +-----+   +---|__/    10K   |>      |+
         |    |     |   |                   |    ===
         |    o |   |   |                   |    /-\
         |  PB  |=| |   |                  ===    |
         |    o |   |   |                  GND    |
         |    |     |   |     +-------------------+
         |    |     |   |  .-----.               .-.
         |   ===    |   +--|Q S D|-VCC           | |
         |   GND    |      |     |      /|       | |10K
         |          |      |_   <|----O< |---+   '-'
         |          |      |Q R  |      \|   |    |
         |          |      '-----'           |    |
         |          |         | 4013         |   ===
         |          |         |              |   GND
         +----------|---------|--------------+
                    |         |    H -> L
                    |   |\    |
                    +---| >O--+
                        |/
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)

The C and R at the set input of the 4013 is a power-up set to make the
Q output high during power on.  The PB silences the buzzer until a new
alarm is detected.

The circuit seems too complicated and I was cracking my head how to
simply it. I would also like the 4013 to be toggled by both H to L as
well as L to H transitions.  How should I do it?

Is there any simpler way to do it?  Any help very much appreciated.

---
I posted an LTspice schematic list for you a little while ago.

Did you miss it?

JF- Hide quoted text -

- Show quoted text -

John,

Sorry about the duplicated posting. I posted twice on the subject on
Sunday and they didn't appear on the newsgroup and so I posted again
on Monday and also didn't appear on the group. They all turned out
this Wednesday morning.

Yes I have seen your LTspice posting and I am downloading the LTspice
software.

Thanks very much

Allen

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