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Help with circuit

J

JimDFB

Jan 1, 1970
0
I would appreciate help with this question.

I have a magnetic lock which I need to provide backup power supply to
(in case power goes down, it needs to function for as long as
possible).

The lock has an adaptor plug (which converts 120-240V 0.3 A mains power
to 12v 1.0 A output).

What I have done is to buy a computer UPS unit (Trust 600 UPS), plug
the UPS to the mans and the mag lock into it. Works BUT, if the power
goes down, it seems to only provide 20 minutes of power and then the
lock opens.

Now, can I use a car battery? I have a 12V car battery 60Ah 450A and
also a car batter charger (which trickle charges and stops
automatically to prevent over charging etc).

I am hoping this will provide me with longer life... however I am not
exactly sure:

1. If I can connect the lock directly to the battery. Do I need to put
in a fuse? Should I buy an inverter to change the 12 v to 220 and then
back to 12 v?
2. Assuming I can connect the lock directly to the battery, can the
battery be hooked up to the charger at the same time? Ideally, I want
the keep the battery hooked up so that it is always full... I realise
it should be run down once in a while

Your help would be greatly appreciated... needless to say, I didn't
want to create a fire hazard or damage the lock.

Regards
 
R

Rich Grise

Jan 1, 1970
0
I would appreciate help with this question.

I have a magnetic lock which I need to provide backup power supply to
(in case power goes down, it needs to function for as long as
possible).

The lock has an adaptor plug (which converts 120-240V 0.3 A mains power
to 12v 1.0 A output).

What I have done is to buy a computer UPS unit (Trust 600 UPS), plug
the UPS to the mans and the mag lock into it. Works BUT, if the power
goes down, it seems to only provide 20 minutes of power and then the
lock opens.

You've got your lock installed backwards. It should be set up so that
you apply power only when you want to open the door, like the buzzer at
apartments.

Good Luck!
Rich
 
J

John Fields

Jan 1, 1970
0
You've got your lock installed backwards. It should be set up so that
you apply power only when you want to open the door, like the buzzer at
apartments.

---
So if there's a fire or something which knocks the power out
everyone is guaranteed to be locked inside?

"Grise"... is that German?
---

You obviously missed that the lock fails open:

"it seems to only provide 20 minutes of power and then the lock
opens."

and that until power fails, control of the lock depends on
whatever's controlling the lock. After that the lock opens.
 
R

redbelly

Jan 1, 1970
0

John said:
So if there's a fire or something which knocks the power out
everyone is guaranteed to be locked inside?

John, that is not a problem for two reasons:

Any lock SHOULD have a mechanical means of controlling it from the
inside, to overide any electronics failure.

Any body who uses a lock without such an overide SHOULD burn to death
in a fire and remove their genes from the human pool.

Regards,

Mark

p.s. Aplogies to anyone who finds my post unduly harsh or Allisonian.
 
C

Chris

Jan 1, 1970
0
JimDFB said:
I would appreciate help with this question.

I have a magnetic lock which I need to provide backup power supply to
(in case power goes down, it needs to function for as long as
possible).

The lock has an adaptor plug (which converts 120-240V 0.3 A mains power
to 12v 1.0 A output).

What I have done is to buy a computer UPS unit (Trust 600 UPS), plug
the UPS to the mans and the mag lock into it. Works BUT, if the power
goes down, it seems to only provide 20 minutes of power and then the
lock opens.

Now, can I use a car battery? I have a 12V car battery 60Ah 450A and
also a car batter charger (which trickle charges and stops
automatically to prevent over charging etc).

I am hoping this will provide me with longer life... however I am not
exactly sure:

1. If I can connect the lock directly to the battery. Do I need to put
in a fuse? Should I buy an inverter to change the 12 v to 220 and then
back to 12 v?
2. Assuming I can connect the lock directly to the battery, can the
battery be hooked up to the charger at the same time? Ideally, I want
the keep the battery hooked up so that it is always full... I realise
it should be run down once in a while

Your help would be greatly appreciated... needless to say, I didn't
want to create a fire hazard or damage the lock.

Regards

Hi, Jim. Sorry for your troubles.

If you look on the Trust website, you'll see that the Trust 600 User
Manual specifies it has a a 12V, 7Ah battery. That means that, if
you're running the battery at a 1 amp load, it will take 7 hours to
discharge. If you're running 1/2A, it will take 14 hours, and so on.
Amp-hours capacity = number of amps load times number of hours.

Also, you should know that an unregulated wall wart is kind of a
squirrely load for a UPS, because it only draws current during the
positive and negative peaks of the AC waveform. Most computer power
supplies are made to draw power more evenly through the AC cycle.

Given those two things, it's possible but not very likely that your 12
watt load would only be powered for 20 minutes (4 watt-hours) with a
UPS through a battery that has a capacity of 84 watt hours. If you
bought your UPS used, you may want to try replacing the battery.

I'm sure the direct hookup of the battery would be OK, at least for a
while. But a 12 watt load is like leaving your running lights on when
you park your car -- it will run down the battery in a day or so.

A car battery in use is being constantly trickle-charged by the
alternator when it's lightly loaded. It does this by regulating the
alternator voltage to 13.8 - 14.2VDC. That's not enough to force the
battery to overcharge, unless you never load it down. Your trickle
charger works like your alternator. So, your battery with trickle
charger hooked up should work OK for your lock circuit, as long as the
trickle charger can crank at least 1 amp (nearly all of them can).
Here's the plan (you'll need a meter to do this):

1) While the lock is energized, use your meter to check the DC voltage
that's being supplied by your wall wart. Let's assume for the sake of
discussion that your meter reads 12.9VDC.

2) Now, set up your battery and trickle charger. Leave it on for a
while, then read the voltage present on the battery. Let's assume for
the sake of discussion it's 14.2VDC.

Now, figure out the difference between the two voltages (1.3V here).
If the wall wart has the same or a higher voltage, you can just connect
the battery/trickle charger directly in place of the wall wart (be sure
to watch polarity -- don't hook it up backwards or you'll let the smoke
out). If the battery/trickle charger voltage is greater, do some sums:

* less than 0.7V greater = 1 diode
* less than 1.4V greater = 2 diodes
* less than 2.1V greater = 3 diodes
* less than 2.8V greater = 4 diodes

and so on. Then hook up your battery/charger to the lock circuit with
some 1N5401 diodes in series as shown (view in fixed font or M$
Notepad):

|
| Charger Lock Ckt
| .-------. 1A .--------.
| | | _ | |
| | +o----o->|-->|---o-\_/o--o+ |
| | | | | |
| | | +| | |
| | | ---12VDC | |
| | | - Battery | |
| | | | | |
| | | | | |
| | -o----o------------ --o- |
| '-------' '--------'
|
(created by AACircuit v1.28.5 beta 02/06/05 www.tech-chat.de)

This example shows two 1N5401 diodes because the example difference was
1.3V -- put as many or as few in series as you need per above. You
should fuse the line running from the battery to the lock circuit for
electrical and fire safety, and to protect the diodes. You can use a
standard automotive fuse if it's available, or a regular fuse is OK.

I hope this has been of help. Feel free to post back if it isn't
clear, or you have further questions.

By the way, the fuse is NOT optional. Make sure to enclose the battery
and fix it in place (but leave vent holes to prevent buildup of
explosive hydrogen gas), and be sure to put insulators over the battery
posts to prevent accidental shorting and explosive failure of the
battery. When it's in use, periodically turn off and disconnect the
charger for a shift to help the battery along by doing a partial
discharge. And periodically touch the battery case to see if it's
heating up -- always a bad sign. It should be cool during normal
usage. Be safe.

Good luck with your project
Chris
 
J

JimDFB

Jan 1, 1970
0
Thanks Chris... very much appreciated. I do not understand why the UPS
does not last long... I bought it new. I did the measurement as
suggested and the voltage dfference is about 1.4v. I need to get hold
of some diodes. Again, thanks!
 
J

John Fields

Jan 1, 1970
0
I would appreciate help with this question.

I have a magnetic lock which I need to provide backup power supply to
(in case power goes down, it needs to function for as long as
possible).

The lock has an adaptor plug (which converts 120-240V 0.3 A mains power
to 12v 1.0 A output).

What I have done is to buy a computer UPS unit (Trust 600 UPS), plug
the UPS to the mans and the mag lock into it. Works BUT, if the power
goes down, it seems to only provide 20 minutes of power and then the
lock opens.

Now, can I use a car battery? I have a 12V car battery 60Ah 450A and
also a car batter charger (which trickle charges and stops
automatically to prevent over charging etc).

I am hoping this will provide me with longer life... however I am not
exactly sure:

1. If I can connect the lock directly to the battery. Do I need to put
in a fuse?

---
Wouldn't hurt, but you'll need to put something pretty big in there
in order to make sure that unless it's a catastrophe the lock stays
where it's supposed to. 5 amp slow blow would probably be a pretty
good choice.
---

Should I buy an inverter to change the 12 v to 220 and then
back to 12 v?

---
No, no, no, a thousand times NO!
---
2. Assuming I can connect the lock directly to the battery, can the
battery be hooked up to the charger at the same time?

---
Yes. Hook up your stuff like this:

+---------+ +---------+
MAINS>----|~ +12|---[1N5822>]--+---|+ |
| ADAPTER | | | LOCK |
MAINS>----|~ -|---+----------|---|- |
+---------+ | |K +---------+
| [1N5822]
| |
| [FUSE]
| |
+---------+ | | +---------+
MAINS>----|~ +12|---|----------+---|+ |
| CHARGER | | | BATTERY |
MAINS>----|~ -|---+--------------|- |
+---------+ +---------+
 
P

petrus bitbyter

Jan 1, 1970
0
John Fields said:
I would appreciate help with this question.

I have a magnetic lock which I need to provide backup power supply to
(in case power goes down, it needs to function for as long as
possible).

The lock has an adaptor plug (which converts 120-240V 0.3 A mains power
to 12v 1.0 A output).

What I have done is to buy a computer UPS unit (Trust 600 UPS), plug
the UPS to the mans and the mag lock into it. Works BUT, if the power
goes down, it seems to only provide 20 minutes of power and then the
lock opens.

Now, can I use a car battery? I have a 12V car battery 60Ah 450A and
also a car batter charger (which trickle charges and stops
automatically to prevent over charging etc).

I am hoping this will provide me with longer life... however I am not
exactly sure:

1. If I can connect the lock directly to the battery. Do I need to put
in a fuse?

---
Wouldn't hurt, but you'll need to put something pretty big in there
in order to make sure that unless it's a catastrophe the lock stays
where it's supposed to. 5 amp slow blow would probably be a pretty
good choice.
---

Should I buy an inverter to change the 12 v to 220 and then
back to 12 v?

---
No, no, no, a thousand times NO!
---
2. Assuming I can connect the lock directly to the battery, can the
battery be hooked up to the charger at the same time?

---
Yes. Hook up your stuff like this:

+---------+ +---------+
MAINS>----|~ +12|---[1N5822>]--+---|+ |
| ADAPTER | | | LOCK |
MAINS>----|~ -|---+----------|---|- |
+---------+ | |K +---------+
| [1N5822]
| |
| [FUSE]
| |
+---------+ | | +---------+
MAINS>----|~ +12|---|----------+---|+ |
| CHARGER | | | BATTERY |
MAINS>----|~ -|---+--------------|- |
+---------+ +---------+
deally, I want
the keep the battery hooked up so that it is always full... I realise
it should be run down once in a while

---
No, keep it topped off all the time.
---
Your help would be greatly appreciated... needless to say, I didn't
want to create a fire hazard or damage the lock.


Hmm, feeling the need to add one remark: Make sure the voltage provided by
the battery is lower then the voltage from the adapter (both measured on the
lock-connections). Otherwise the battery may go halfway empty before the
adapter takes over.

petrus bitbyter
 
C

Chris

Jan 1, 1970
0
JimDFB said:
Chris

The lock has a rating of 12-24 voltage... does this mean that I would
be OK with the 14.2 V the charger sends out or do I need to reduce the
voltage with the diodes? Thanks and regards. The lock details are here
http://www.fastaccesssecurity.com/ce-approved-locks.asp?model=FAS-600MSD

Hi, Jim. Wishful thinking. It says it has "dual voltage". That means
there's a connection for 12V, and a connection for 24V. This doesn't
sound like you can put up to 24V on the 12V terminal. Probably a split
coil:

|
| 24V
| o-----.
| |
| C|
| C|
| C|
| 12V |
| o-----o
| |
| C|
| C|
| C|
| COM |
| o-----'
|
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)


There's also the question of the voltage requirement for whatever's
controlling the lock.

If you try to duplicate your existing power supply as closely as
possible with your battery/trickle charger, it _should_ be OK. You
were asking specifically about replacing a wall wart. I can't tell you
about how your security system is wired, or what else is connected.

Good luck
Chris
 
J

JimDFB

Jan 1, 1970
0
Hi, Jim. Wishful thinking

Yes, it was rather. I appreciate everyone's help. I have ordered the
diodes and will get it all sorted soon. Regards
 
C

Chris

Jan 1, 1970
0
JimDFB said:
Chris

The lock has a rating of 12-24 voltage... does this mean that I would
be OK with the 14.2 V the charger sends out or do I need to reduce the
voltage with the diodes? Thanks and regards. The lock details are here
http://www.fastaccesssecurity.com/ce-approved-locks.asp?model=FAS-600MSD

One more thing, Jim. Sorry, but the thought just occurred to me now.

I'm guessing your wall wart is an unregulated 12VDC, since it's being
used to drive a solenoid. If it's not, any other circuitry may be
relying on a regulated supply, and you might end up with big problems
here.

An easy way to check is to measure the wall wart voltage with the
solenoid off, then with it on. If the output voltage goes down by more
than 50mV or so, it's unregulated, and all the advice above is OK. If
the output voltage stays the same, post again -- you'll need another
solution.

Cheers
Chris
 
J

JimDFB

Jan 1, 1970
0
Hi Chris. The only other circutry is a controller
http://store.yahoo.com/linear-access-controls/sindoorgatco.html. It
says: Installation and set-up are simple. The AP-4 operates on 12-24
volts, ac or dc. It can be powered directly from the radio power output
of most gate operators. Installation and set-up are simple. Power
Input: low voltage plug in transformer or power from access device
12-24 .
 
J

JimDFB

Jan 1, 1970
0
sorry didn't complete the posting before posting it:

Hi Chris. The only other circutry is a controller
http://store.yahoo.com/linear-access-controls/sindoorgatco.html. It
says: Installation and set-up are simple. The AP-4 operates on 12-24
volts, ac or dc. It can be powered directly from the radio power output

of most gate operators. Installation and set-up are simple. Power
Input: low voltage plug in transformer or power from access device
12-24 volts AC/DC.

Does this answer the question? Regads
 
C

Chris

Jan 1, 1970
0
JimDFB said:
sorry didn't complete the posting before posting it:

Hi Chris. The only other circutry is a controller
http://store.yahoo.com/linear-access-controls/sindoorgatco.html. It
says: Installation and set-up are simple. The AP-4 operates on 12-24
volts, ac or dc. It can be powered directly from the radio power output

of most gate operators. Installation and set-up are simple. Power
Input: low voltage plug in transformer or power from access device
12-24 volts AC/DC.

Does this answer the question? Regads

You're good to go, Jim

Good luck
Chris
 
J

John Fields

Jan 1, 1970
0
John Fields said:
I would appreciate help with this question.

I have a magnetic lock which I need to provide backup power supply to
(in case power goes down, it needs to function for as long as
possible).

The lock has an adaptor plug (which converts 120-240V 0.3 A mains power
to 12v 1.0 A output).

What I have done is to buy a computer UPS unit (Trust 600 UPS), plug
the UPS to the mans and the mag lock into it. Works BUT, if the power
goes down, it seems to only provide 20 minutes of power and then the
lock opens.

Now, can I use a car battery? I have a 12V car battery 60Ah 450A and
also a car batter charger (which trickle charges and stops
automatically to prevent over charging etc).

I am hoping this will provide me with longer life... however I am not
exactly sure:

1. If I can connect the lock directly to the battery. Do I need to put
in a fuse?

---
Wouldn't hurt, but you'll need to put something pretty big in there
in order to make sure that unless it's a catastrophe the lock stays
where it's supposed to. 5 amp slow blow would probably be a pretty
good choice.
---

Should I buy an inverter to change the 12 v to 220 and then
back to 12 v?

---
No, no, no, a thousand times NO!
---
2. Assuming I can connect the lock directly to the battery, can the
battery be hooked up to the charger at the same time?

---
Yes. Hook up your stuff like this:

+---------+ +---------+
MAINS>----|~ +12|---[1N5822>]--+---|+ |
| ADAPTER | | | LOCK |
MAINS>----|~ -|---+----------|---|- |
+---------+ | |K +---------+
| [1N5822]
| |
| [FUSE]
| |
+---------+ | | +---------+
MAINS>----|~ +12|---|----------+---|+ |
| CHARGER | | | BATTERY |
MAINS>----|~ -|---+--------------|- |
+---------+ +---------+
deally, I want
the keep the battery hooked up so that it is always full... I realise
it should be run down once in a while

---
No, keep it topped off all the time.
---
Your help would be greatly appreciated... needless to say, I didn't
want to create a fire hazard or damage the lock.


Hmm, feeling the need to add one remark: Make sure the voltage provided by
the battery is lower then the voltage from the adapter (both measured on the
lock-connections). Otherwise the battery may go halfway empty before the
adapter takes over.
 
J

John Fields

Jan 1, 1970
0
thanks John

---
You're welcome, but due to Petrus' input it's back to the drawing
board:

This _will_ work:

.. +---------+
.. MAINS>--|~ +12|-----+----+
.. | ADAPTER | | | O----->To lock +12V
.. MAINS>--|~ -|--+ | [COIL] - -|
.. +---------+ | | | O--> |<--O
.. +--|----+ |NO NC|
.. | +-------+ |
.. | +------+
.. | |
.. +------------|-------->To lock GND/0V
.. | |
.. +---------+ | | +---------+
.. MAINS>--|~ +12|--|------------+--|+ |
.. | CHARGER | | | BATTERY |
.. MAINS>--|~ -|--+ --------------|- |
.. +---------+ +---------+
..

Where the relay is any small 12V coil relay capable of hot-switching
an amp and a half.

Or, if the additional load from the relay coil is too great for the
adapter to bear, you could get a 120VAC coil relay and run it off
the mains, like this:


.. +---------+ NO NC
.. MAINS>-+---|~ +12|------O--> |<--O
.. | | ADAPTER | [COIL] | |
.. MAINS>-|-+-|~ -|--+ | | O-------->To lock +12V
.. | | +---------+ | | | |
.. | | | | | |
.. +-|--------------|--+ | |
.. | +--------------|-----+ |
.. | | | |
.. | | +------------|---->To lock GND/0V
.. | | | |
.. | | +---------+ | | +---------+
.. +-|-|~ +12|--|------------+--|+ |
.. | | CHARGER | | | BATTERY |
.. +-|~ -|--+---------------|- |
.. ++---------+ +---------+

This will get you complete isolation between the adapter and the
battery/charger, which is a good thing.
 
J

JimDFB

Jan 1, 1970
0
Many thanks for the combined mains adapter and charger option but I am
not sure if I gain anything by having both the battery (hooked up to
the charger) AND the mains adapter at the same time. Seems to me
charger+battery only covers all needs, or am I missing something?

Regards
 
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