Hi all,

its been a while since I played with electronics, so could do with some
advice.

I have 2 magnetic door locks, keypad operated to control access into my
house. I also have a mains power smoke alarm system.

what I want to do is use a relay operated by the smoke alarm when sounding
to turn off the mag locks to allow people to leave with out having to get
their fobs out.

system was working fine with one mag lock, but now I have two I have a
problem. the smoke alarm when operating shorts out 2 wires going to the one
maglocks power supply. the electricians has simply connected those wires to
to the same connections in the new power supply. the problem is now that if
someone opens the back door with a fob, the front door also unlocks! and
vice versa. I was thinking about using diodes to try to get round this
problem. I'm not sure if I have explained the set up very well..so ask away
if you have any questions!

Cheers

Steve

"Mr Sandman" wrote in message
news:WcSdnQ1Etp-cdZnVnZ2dnUVZ8qSnnZ2d@plusnet...
Hi all,

its been a while since I played with electronics, so could do with some
advice.

I have 2 magnetic door locks, keypad operated to control access into my
house. I also have a mains power smoke alarm system.

what I want to do is use a relay operated by the smoke alarm when sounding
to turn off the mag locks to allow people to leave with out having to get
their fobs out.

Mmm. So to break into your house, I stick a smoke bomb in and I can open the
doors?

cheers,
clive

"Clive George" wrote in message
news:qbOdnSfEM9_idJnVnZ2dnUVZ8vednZ2d@plusnet...
"Mr Sandman" wrote in message
news:WcSdnQ1Etp-cdZnVnZ2dnUVZ8qSnnZ2d@plusnet...
Hi all,

its been a while since I played with electronics, so could do with some
advice.

I have 2 magnetic door locks, keypad operated to control access into my
house. I also have a mains power smoke alarm system.

what I want to do is use a relay operated by the smoke alarm when
sounding to turn off the mag locks to allow people to leave with out
having to get their fobs out.

Mmm. So to break into your house, I stick a smoke bomb in and I can open
the doors?

cheers,
clive
Yep, a very common method of breaking into houses I'm sure.

Steve

"Mr Sandman" wrote in message
news:WcSdnQ1Etp-cdZnVnZ2dnUVZ8qSnnZ2d@plusnet...
Hi all,

its been a while since I played with electronics, so could do with some
advice.

I have 2 magnetic door locks, keypad operated to control access into my
house. I also have a mains power smoke alarm system.

what I want to do is use a relay operated by the smoke alarm when sounding
to turn off the mag locks to allow people to leave with out having to get
their fobs out.

system was working fine with one mag lock, but now I have two I have a
problem. the smoke alarm when operating shorts out 2 wires going to the
one maglocks power supply. the electricians has simply connected those
wires to to the same connections in the new power supply. the problem is
now that if someone opens the back door with a fob, the front door also
unlocks! and vice versa. I was thinking about using diodes to try to get
round this problem. I'm not sure if I have explained the set up very
well..so ask away if you have any questions!

Two pole relay.

On Tue, 15 Apr 2008 18:38:04 +0100, "Mr Sandman" wrote:

the problem is now that if
someone opens the back door with a fob, the front door also unlocks! and
vice versa. I was thinking about using diodes to try to get round this
problem. I'm not sure if I have explained the set up very well..so ask away
if you have any questions!

If it's a DC sensing circuit, then yes a diode in one leg of each branch will do
the trick. If it doesn't work at all one way, reverse it.

If it's AC sensing it wouldn't make any difference. I'd guess and you'd have to
go the relay route.

Be careful though, it's might be mains voltage !!!! Get something sturdy, 1A
rated at 400v. They only cost pence anyway.

Andy

"Andy Cap" wrote in message
...
On Tue, 15 Apr 2008 18:38:04 +0100, "Mr Sandman"
wrote:

the problem is now that if
someone opens the back door with a fob, the front door also unlocks! and
vice versa. I was thinking about using diodes to try to get round this
problem. I'm not sure if I have explained the set up very well..so ask
away
if you have any questions!

If it's a DC sensing circuit, then yes a diode in one leg of each branch
will do
the trick. If it doesn't work at all one way, reverse it.

If it's AC sensing it wouldn't make any difference. I'd guess and you'd
have to
go the relay route.

Be careful though, it's might be mains voltage !!!! Get something
sturdy, 1A
rated at 400v. They only cost pence anyway.

Andy


Hi Andy. thanks for the useful response! Its just 12 Volts DC, so I can dig
a couple of diodes out of an old PCB somewhere I'm sure. Where do you
suggest I put them? one on each of the wires to the power supplies? I'm
sure I can have a play, cant do any harm. I suppose there must be some
electron transfer in some direction across the sensing terminals, I just
need to find out which is positive I imagine?

cheers!

Steve

On Tue, 15 Apr 2008 19:48:39 +0100, "Mr Sandman" wrote:


Hi Andy. thanks for the useful response! Its just 12 Volts DC, so I can dig
a couple of diodes out of an old PCB somewhere I'm sure. Where do you
suggest I put them? one on each of the wires to the power supplies? I'm
sure I can have a play, cant do any harm. I suppose there must be some
electron transfer in some direction across the sensing terminals, I just
need to find out which is positive I imagine?

cheers!

Steve

12v is ideal. Just put diode into one of the wires arriving at the lock.

Repeat for the other lock, same wire with diode in the same direction, (ring
nearest lock for example).

If locks fail to work, reverse the diodes.

Andy

Andy Cap wrote:
On Tue, 15 Apr 2008 19:48:39 +0100, "Mr Sandman" wrote:

Hi Andy. thanks for the useful response! Its just 12 Volts DC, so I can dig
a couple of diodes out of an old PCB somewhere I'm sure. Where do you
suggest I put them? one on each of the wires to the power supplies? I'm
sure I can have a play, cant do any harm. I suppose there must be some
electron transfer in some direction across the sensing terminals, I just
need to find out which is positive I imagine?

cheers!

Steve

12v is ideal. Just put diode into one of the wires arriving at the lock.

Repeat for the other lock, same wire with diode in the same direction, (ring
nearest lock for example).

If locks fail to work, reverse the diodes.

Andy

Your diodes may need a high voltage rating plus a snubber to
survive. Too tired to think it thru properly.


NT

On Tue, 15 Apr 2008 18:38:04 +0100, Mr Sandman wrote:

Hi all,

its been a while since I played with electronics, so could do with some
advice.

I have 2 magnetic door locks, keypad operated to control access into my
house. I also have a mains power smoke alarm system.

what I want to do is use a relay operated by the smoke alarm when
sounding to turn off the mag locks to allow people to leave with out
having to get their fobs out.


So the maglocks de-energise to release, I assume. That's normally the
case.

system was working fine with one mag lock, but now I have two I have a
problem. the smoke alarm when operating shorts out 2 wires going to the
one maglocks power supply.

So you have separate power supplies for each maglock now?

the electricians has simply connected those
wires to to the same connections in the new power supply. the problem
is now that if someone opens the back door with a fob, the front door
also unlocks! and vice versa.

So both maglocks have now been put on the same power supply, fed from the
alarm panel, or both maglocks are fed from the same alarm panel terminals?

I was thinking about using diodes to try
to get round this problem. I'm not sure if I have explained the set up
very well..so ask away if you have any questions!



To use two maglocks you need two sets of terminals in the alarm panel,
one pair for the front maglock and the other for the back one. They have
to be wired to separate terminals otherwise your system won't work - as
you've found out. If you only have a single set of terminals then you'll
need to look for a new panel or a suitable second-door adaptor (if one is
available for that unit). It's quite possible that the electrician has
connected your panel in the only way possible!

For the smoke alarm you need to add a 2-pole relay, operated by the
signal from the smoke detector. Each pole of the relay is then connected
in series with a maglock. From your description it sounds as if the alarm
has a single volt-free contact, so you need to power the relay from
somewhere - probably at 12 or 24v via a transformer as such contacts are
rarely rated for mains voltage. You would use the normally-closed
contacts on the relays so that they cut off the maglock supplies when the
relay operates.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net
Filtering everything posted from googlegroups to kill spam.

Hi all,

its been a while since I played with electronics, so could do with some
advice.

I have 2 magnetic door locks, keypad operated to control access into my
house. I also have a mains power smoke alarm system.

what I want to do is use a relay operated by the smoke alarm when
sounding to turn off the mag locks to allow people to leave with out
having to get their fobs out.


So the maglocks de-energise to release, I assume. That's normally the
case.

Yep.


system was working fine with one mag lock, but now I have two I have a
problem. the smoke alarm when operating shorts out 2 wires going to the
one maglocks power supply.

So you have separate power supplies for each maglock now?

yes, i added a new seperat set up to the back door. The sytem i am using in
both cases is an EZ-tag from TLC -
http://www.tlc-direct.co.uk/Products/EZTAGKIT.html the keypad sends a signal
back to the power suply to tell it to energise or de energise the mag lock.
both systems have to be seperate or when someone opens the back door, the
front door also deenergises.


the electricians has simply connected those
wires to to the same connections in the new power supply. the problem
is now that if someone opens the back door with a fob, the front door
also unlocks! and vice versa.

So both maglocks have now been put on the same power supply, fed from the
alarm panel, or both maglocks are fed from the same alarm panel terminals?

There is no alarm panel.


I was thinking about using diodes to try
to get round this problem. I'm not sure if I have explained the set up
very well..so ask away if you have any questions!



To use two maglocks you need two sets of terminals in the alarm panel,
one pair for the front maglock and the other for the back one. They have
to be wired to separate terminals otherwise your system won't work - as
you've found out. If you only have a single set of terminals then you'll
need to look for a new panel or a suitable second-door adaptor (if one is
available for that unit). It's quite possible that the electrician has
connected your panel in the only way possible!

For the smoke alarm you need to add a 2-pole relay, operated by the
signal from the smoke detector. Each pole of the relay is then connected
in series with a maglock. From your description it sounds as if the alarm
has a single volt-free contact, so you need to power the relay from
somewhere - probably at 12 or 24v via a transformer as such contacts are
rarely rated for mains voltage. You would use the normally-closed
contacts on the relays so that they cut off the maglock supplies when the
relay operates.

it is a possibliity to use a relay yes, but i was hoping a couple of diodes
would also work.

Steve

"Owain" wrote in message
news:3omdnW6B8-62v5jVnZ2dnUVZ8qfinZ2d@plusnet...
Mr Sandman wrote:
what I want to do is use a relay operated by the smoke alarm when
sounding to turn off the mag locks to allow people to leave with out
having to get their fobs out.

What happens if the power supply fails?

If they're on an exit route then locks should have a mechanical release,
or be fail-safe ie release autoimatically when the power is off (ie
magnetic locks, rather than magnetic lock releases)

Owain

----- Original Message -----
From: "Owain"
Newsgroups: uk.do-i-y
Sent: Tuesday, April 15, 2008 10:38 PM
Subject: Electronics advice pls.


Mr Sandman wrote:
what I want to do is use a relay operated by the smoke alarm when
sounding to turn off the mag locks to allow people to leave with out
having to get their fobs out.

What happens if the power supply fails?

If they're on an exit route then locks should have a mechanical release,
or be fail-safe ie release autoimatically when the power is off (ie
magnetic locks, rather than magnetic lock releases)

Owain


if the supply fails, the locks release because they no longer have any
power.


Steve

"Andy Cap" wrote in message
...
On Tue, 15 Apr 2008 19:48:39 +0100, "Mr Sandman"
wrote:


Hi Andy. thanks for the useful response! Its just 12 Volts DC, so I can
dig
a couple of diodes out of an old PCB somewhere I'm sure. Where do you
suggest I put them? one on each of the wires to the power supplies? I'm
sure I can have a play, cant do any harm. I suppose there must be some
electron transfer in some direction across the sensing terminals, I just
need to find out which is positive I imagine?

cheers!

Steve

12v is ideal. Just put diode into one of the wires arriving at the lock.

Repeat for the other lock, same wire with diode in the same direction,
(ring
nearest lock for example).

If locks fail to work, reverse the diodes.

Andy

Thanks Andy.

Just to clarify then...or try to! I have two sets of terminals one on each
powersupply, these are called P and B. The keypad shorts P & B together to
switch the power on to the mag locks. So i have a wire coming from the
keypad to both terminals. Both power suppys are set up the same. Then i
have two wires coming from the smoke alarm activated relay. these two wires
go short curuit when the alarm sounds. if i conect these two wires to one
of the power supplys P&B terminals, it all works as planed, ie the door
unlocks, but the electrition has put a wire from the terminals on that power
supplys P&B terminals to the new power supplys P&B terminals. this causes
both power supplys to cut power to the maglocks when the smoke alarm sounds,
but also when one keypad operates it also causes the other doors maglock to
yurn off. So where do i put the diodes so that the smoke alarm relay
operates both power supplys P&B terminals, but dosent allow one power
supplys keypad to short the other keypads power supply P&B?

Hehe

Steve

On Tue, 15 Apr 2008 18:38:04 +0100, "Mr Sandman"
wrote:

what I want to do is use a relay operated by the smoke alarm when sounding
to turn off the mag locks to allow people to leave with out having to get
their fobs out.

You should have an emergency exit switch on the wall by the door which
de-energises the lock when pressed. To have a final exit door which
requires either a carried device to open from the inside or a smoke
alarm to function is not terribly bright.

"Peter Parry" wrote in message
...
On Tue, 15 Apr 2008 18:38:04 +0100, "Mr Sandman"
wrote:

what I want to do is use a relay operated by the smoke alarm when sounding
to turn off the mag locks to allow people to leave with out having to get
their fobs out.

You should have an emergency exit switch on the wall by the door which
de-energises the lock when pressed. To have a final exit door which
requires either a carried device to open from the inside or a smoke
alarm to function is not terribly bright.

There is a final door exit button, but its pretty useless if you cant see
it. Some of us have visual impairments.

Steve

"Mr Sandman" wrote in message
news:zZ6dnRwwuJIQN5jVnZ2dnUVZ8uidnZ2d@plusnet...

"Peter Parry" wrote in message
...
On Tue, 15 Apr 2008 18:38:04 +0100, "Mr Sandman"
wrote:

what I want to do is use a relay operated by the smoke alarm when
sounding
to turn off the mag locks to allow people to leave with out having to get
their fobs out.

You should have an emergency exit switch on the wall by the door which
de-energises the lock when pressed. To have a final exit door which
requires either a carried device to open from the inside or a smoke
alarm to function is not terribly bright.

There is a final door exit button, but its pretty useless if you cant see
it. Some of us have visual impairments.

Steve

I'll try again..
two pole relay..
connect the NC contacts, one to each door magnet..
energise the relay from the alarm..
alarm off the system is as before..
alarm on the relay breaks contacts to both doors.
What could be easier?

On Wed, 16 Apr 2008 08:09:43 +0100, "Mr Sandman" wrote:


Just to clarify then...or try to! I have two sets of terminals one on each
powersupply, these are called P and B. The keypad shorts P & B together to
switch the power on to the mag locks. So i have a wire coming from the
keypad to both terminals. Both power suppys are set up the same. Then i
have two wires coming from the smoke alarm activated relay. these two wires
go short curuit when the alarm sounds. if i conect these two wires to one
of the power supplys P&B terminals, it all works as planed, ie the door
unlocks, but the electrition has put a wire from the terminals on that power
supplys P&B terminals to the new power supplys P&B terminals. this causes
both power supplys to cut power to the maglocks when the smoke alarm sounds,
but also when one keypad operates it also causes the other doors maglock to
yurn off. So where do i put the diodes so that the smoke alarm relay
operates both power supplys P&B terminals, but dosent allow one power
supplys keypad to short the other keypads power supply P&B?


Just try and get one working first.
Remove the wire from the Smoke Alarm that connects to the lock P terminal and
connect the diode. Reconnect the wire to the other end of the diode.
Test to see if the SA still operated the lock. If not reverse it.
If neither way works, as dennis@home says, the relay route is probably easiest.
If just one direction works, then connect the other diode in EXACTLY the same
place and orientation.

HTH
Andy

"dennis@home" wrote in message
...


"Mr Sandman" wrote in message
news:zZ6dnRwwuJIQN5jVnZ2dnUVZ8uidnZ2d@plusnet...

"Peter Parry" wrote in message
...
On Tue, 15 Apr 2008 18:38:04 +0100, "Mr Sandman"
wrote:

what I want to do is use a relay operated by the smoke alarm when
sounding
to turn off the mag locks to allow people to leave with out having to
get
their fobs out.

You should have an emergency exit switch on the wall by the door which
de-energises the lock when pressed. To have a final exit door which
requires either a carried device to open from the inside or a smoke
alarm to function is not terribly bright.

There is a final door exit button, but its pretty useless if you cant see
it. Some of us have visual impairments.

Steve

I'll try again..
two pole relay..
connect the NC contacts, one to each door magnet..
energise the relay from the alarm..
alarm off the system is as before..
alarm on the relay breaks contacts to both doors.
What could be easier?

Yes the relay is an option, but I am asking for assistance with the
possibility of a diode based solution, I.e. no mechanical element.

Steve

"Andy Cap" wrote in message
...
On Wed, 16 Apr 2008 08:09:43 +0100, "Mr Sandman"
wrote:


Just to clarify then...or try to! I have two sets of terminals one on
each
powersupply, these are called P and B. The keypad shorts P & B together
to
switch the power on to the mag locks. So i have a wire coming from the
keypad to both terminals. Both power suppys are set up the same. Then i
have two wires coming from the smoke alarm activated relay. these two
wires
go short curuit when the alarm sounds. if i conect these two wires to one
of the power supplys P&B terminals, it all works as planed, ie the door
unlocks, but the electrition has put a wire from the terminals on that
power
supplys P&B terminals to the new power supplys P&B terminals. this causes
both power supplys to cut power to the maglocks when the smoke alarm
sounds,
but also when one keypad operates it also causes the other doors maglock
to
yurn off. So where do i put the diodes so that the smoke alarm relay
operates both power supplys P&B terminals, but dosent allow one power
supplys keypad to short the other keypads power supply P&B?


Just try and get one working first.
Remove the wire from the Smoke Alarm that connects to the lock P terminal
and
connect the diode. Reconnect the wire to the other end of the diode.
Test to see if the SA still operated the lock. If not reverse it.
If neither way works, as dennis@home says, the relay route is probably
easiest.
If just one direction works, then connect the other diode in EXACTLY the
same
place and orientation.

HTH
Andy



Cheers Andy, that's what I was thinking too, will have a go and let you know
how I get one.

cheers

Steve

On Wed, 16 Apr 2008 08:28:04 +0100, "Mr Sandman"
wrote:

To have a final exit door which
requires either a carried device to open from the inside or a smoke
alarm to function is not terribly bright.

There is a final door exit button, but its pretty useless if you cant see
it. Some of us have visual impairments.

In a fire at night (the most common time for fatal fires) everyone has
visual impairment. If you are used to it that gives you an advantage.
The three most common places to find bodies after a fire are under
beds and in wardrobes (usually children) and against the front door
(mostly adults looking for a key to get out).

If you want to wire things up to smoke alarms that's fine - but don't
do it at the expense of far more useful functions like exit releases.
If they are not easy to find where they are now then moving them and
making them easy to find in the dark by feel should be a much higher
priority than playing with smoke alarms.

As for the smoke alarm wiring - personally I'd put a single relay
controlling a no volt release switch on the input side of the power
supply or mains feed to the door magnets. That way once the smoke
alarm goes off the doors open and can't re-lock. Using relays alone
on the smoke alarm circuit to control the locks simply means that when
the smoke alarms stop working the doors can re-lock - not a good idea
as the fire is developed by then.

I assume you are talking of magnetic plate door locks such as:-
http://www.screwfix.com/prods/72119/Security/Access-Control/Electromagnets/Standard-Single-Magnet-Door-Lock-12-24V
http://tinyurl.com/52pcum

and not the sort shown here :-

http://www.screwfix.com/prods/19768/Security/Access-Control/Door-Entry-Systems/Door-Entry-Kit-Rim-Lock-Release
http://tinyurl.com/3uhplw

An NVR switch unsets on power failure and won't restore the lock
supply until manually reset by physically pressing the on button..
There is therefore no possibility of the door lock re-energising when
you don't want it to after the alarm has gone off.

http://www.axminster.co.uk/pricing/INC/recno/4/cid/JVR7W1QUAQR7KGMAA97FQW0GZXGBN435/product-Axminster-Light-Duty-NVR-Switch-21280.htm
http://tinyurl.com/3lty73

Hi
Having read the postings so far would like to add the following.
From descriptions diode switching may be possible if both locks share the
same supply and readers are dc controlled.4 diodes could be used as follows.
Remove 'open' wire from lock release and fit diode in series at both locks
..(test to see if working if not reverse diodes.)
Feed smoke relay from supply ,switched contact is now connected through a
further diode to each controller 'open' contact.

I agree with others on the group this is not the total solution HSE
requirements for fire doors are that they must be fail release in fire and
must have break-glass release points at each door if no mechanical opener is
fitted.
As for visual impairment or indeed other disabilities,regulations are in
place for correct equipment to suit most needs .IME most disabled people can
find a fire exit and open it with ease if the correct equipment is used and
visually impaired systems emit a tone when activated or even talk.
As already suggested look at the door release before the electronics .

HTH
CJ