Maker Pro
Maker Pro

Help designing a circuit please

S

Simon Taylor

Jan 1, 1970
0
Hi,

I have little or no experience in designing circuits and need some
help.... Please!

I have a 24V line out to a contact block. The 24V is connected across
1&4 and a 2-position valve is connected across 2&3. When the 24V is
applied, the valve switches to position 2, and when it is switched
off, it switches back to pos 2.

I want to connect another piece of kit with a contact closure across
this, so that when the valve switches direction, it closes the
contact.
ie when it switches to 2, the contact is closed, and when it switches
back to 1 the contact is closed again. Effectively sending a pulse at
each valve switch.

Obviously, simply connecting these in parallel will not work - the
contact will only close once.

I have a few ideas (logic gates, capacitors) etc, but no idea how to
implement them!!
Help would be greatly appreciated! Please either reply here or email
comments to the hotmail address above or
simondeane@"!DONTSPAM!"bigfoot.com.

Many thanks,
Si
 
F

Frank Bemelman

Jan 1, 1970
0
Simon Taylor said:
Hi,

I have little or no experience in designing circuits and need some
help.... Please!

I have a 24V line out to a contact block. The 24V is connected across
1&4 and a 2-position valve is connected across 2&3. When the 24V is
applied, the valve switches to position 2, and when it is switched
off, it switches back to pos 2.

I want to connect another piece of kit with a contact closure across
this, so that when the valve switches direction, it closes the
contact.
ie when it switches to 2, the contact is closed, and when it switches
back to 1 the contact is closed again. Effectively sending a pulse at
each valve switch.

Obviously, simply connecting these in parallel will not work - the
contact will only close once.

I have a few ideas (logic gates, capacitors) etc, but no idea how to
implement them!!
Help would be greatly appreciated! Please either reply here or email
comments to the hotmail address above or
simondeane@"!DONTSPAM!"bigfoot.com.

So your input looks like this:

__________
------------' '-----------

And you want this:
__ __
------------' '-------' '----------

I'd use an optocoupler to convert the 24V signal to
logic level. Followed by a MC4538 dual timer. The timer
set at 250mS (???) or whatever length you prefer.
The two outputs of the dual timer or-ed together with
two diodes, and a transistor to drive a relay. With
that relay contact you can control whatever you like.

The MC4538 dual timer can be wired so that one of it's
timers responds to the falling edge of the input, and
the 2nd timer to respond to the rising edge.

You have to realize that a very fast double change
(on and off) of the valve can result in just one
output pulse, two pulses are generated, but they
will overlap, resulting in one pulse. If that is a
problem, something else is needed.
 
S

Simon Taylor

Jan 1, 1970
0
Frank, you are a star!

Sounds like exactly what I'm after.

I do need to connect that circuit up in parallel with the valve, so
that the valve signal still looks like this,
__________
------------' '-----------

But sends this signal to a different unit:
__ __
------------' '-------' '----------

Is that possible by just connecting them in parallel, with that
circuit inbetween?
 
F

Frank Bemelman

Jan 1, 1970
0
Simon Taylor said:
Frank, you are a star!

Sounds like exactly what I'm after.

I do need to connect that circuit up in parallel with the valve, so
that the valve signal still looks like this,
__________
------------' '-----------

But sends this signal to a different unit:
__ __
------------' '-------' '----------

Is that possible by just connecting them in parallel, with that
circuit inbetween?

The circuit needs power too, for the 2nd pulse:
__________
------------' '-----------
__ __
------------' '-------' '----------
1 2

Only two parallel wires is not enough, it would
look more like this:

,----------------------------------------oB
+24V ----- switch -----------------------oA |
| | |
valve black box
| | | |
GND--------------------------------------o o o
C D E
different
unit


So, three wires into the box, and two coming out of it.
 
S

Simon Taylor

Jan 1, 1970
0
The circuit needs power too, for the 2nd pulse:

1 2

Only two parallel wires is not enough, it would
look more like this:

,----------------------------------------oB
+24V ----- switch -----------------------oA |
| | |
valve black box
| | | |
GND--------------------------------------o o o
C D E
different
unit


So, three wires into the box, and two coming out of it.

Thanks for the Reply Frank...

I'm sorry but my grasp of electronics is not too great (or anywhere near
adequate) you may have to hold my hand a little here - I'm guessing the
black box is the optocoupler/timer/etc, or is that the switch?
The thing that's confusing me is which bits connect where..

The contact block on the back of the instrument (which is connected to the
valve) is labelled 1-10 and connected like this:
________________
| |
1 2 3 4 5etc
24V GND
| |
| |
Valve

Ie 1 and 4 are bridged and 2/3 connect to the valve. 3/4 operate as a
contact closure (the same connection is on the back of the additonal unit,
which needs a pulse)

My question is, would contact C be connected to the GND and A to the 24V?
If so, where does B connect to?

I really appreciate your help, and if it's easier to contact via email, you
can do so vis simon@TAKE ME OUTtaylorsd.fslife.co.uk

Thanks for your time,
Si
 
F

Frank Bemelman

Jan 1, 1970
0
Simon Taylor said:
Thanks for the Reply Frank...

I'm sorry but my grasp of electronics is not too great (or anywhere near
adequate) you may have to hold my hand a little here - I'm guessing the
black box is the optocoupler/timer/etc, or is that the switch?
The thing that's confusing me is which bits connect where..

The contact block on the back of the instrument (which is connected to the
valve) is labelled 1-10 and connected like this:
________________
| |
1 2 3 4 5etc
24V GND
| |
| |
Valve

Ie 1 and 4 are bridged and 2/3 connect to the valve. 3/4 operate as a
contact closure (the same connection is on the back of the additonal unit,
which needs a pulse)

My question is, would contact C be connected to the GND and A to the 24V?
If so, where does B connect to?

I really appreciate your help, and if it's easier to contact via email, you
can do so vis simon@TAKE ME OUTtaylorsd.fslife.co.uk

Yes, the black box is the opto & timer. I don't have a problem holding your
hand, but if you really know little about electronics, you better buy two
industrial timers, or a very small PLC (EASY, LOGO) and wire that up.

Your instrument has a 230V input as well? I guess that terminal strip
delivers
24VDC, on terminals 2(GND) and 1(+24). Terminal 4 is a spare, and has a wire
to 1, or is it just a contact output? If there is nothing else connected to
3&4 it probably is.

In that case, the 'C' from the black box connects to 2(GND) and wire to
valve. 'B' goes to terminal 1 (24V). 'A' goes to 3 (contact from instrument
and wire to valve).

The black box should contain a 7815 (15V) regulator for the CD4538.

But you won't be able to build that black box on your own, I'm afraid.

If this is anything professional, you better ask/find a technician that
can install a small PLC and make it work.
 
S

Simon Taylor

Jan 1, 1970
0
Thanks for the help frank - you have been most helpful and kind, but i
suspect you're right and I may not be able to take this any further on
my own...

Thanks again,

Simon
 
Top