UPS for 12V DC ?

[Viel Spass]

I am looking for some ideas. I have an answering machine runnning off
a 12 VDC transformer.

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

Thanks.

 

[John Fields]

On Mon, 4 Aug 2008 12:06:43 -0700 (PDT), Viel Spass
<andy77017@yahoo.com> wrote:

I am looking for some ideas. I have an answering machine runnning off
a 12 VDC transformer.

---
There is no such thing; you must be referring to an AC to DC
wall-wart, yes?
---

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

---
You can.
Do you have any test equipment?

Assuming your answering machine doesn't draw 200 mA all the time, why
not use a sealed lead-acid battery and a couple of Schottky diodes
instead and use your wall-wart to charge the battery and run the
answering machine at the same time?

Then when the mains go down, battery power will be steered into the
answering machine seamlessly and the answering machine will stay on
for as long as the battery can keep it on.

That's a 12V UPS.

View in Courier:

WALL ANS.
WART MACH
+----+ +----+
MAINS>--|~ +|--[1N5817>]-+-[1N5817>]--|+ |
| | |+ | |
| } [BAT] | |
| | | | |
MAINS>--|~ -|------------+------------|- |
+----+ +----+

JF

 

[John Fields]

On Tue, 05 Aug 2008 10:14:07 -0700, Dave <nohomme@mail.com> wrote:

John Fields wrote:
WALL ANS.
WART MACH
+----+ +----+
MAINS>--|~ +|--[1N5817>]-+-[1N5817>]--|+ |
| | |+ | |
| } [BAT] | |
| | | | |
MAINS>--|~ -|------------+------------|- |
+----+ +----+

JF

Hi John,

Very cool solution but why do you say, "Assuming your answering machine
doesn't draw 200 mA?"

---
"... doesn't draw 200mA all the time."
---

Is that the max those diodes can use?

---
No, those are 20V 1A Schottky diodes use to keep the forward drop low:

http://www.onsemi.com/pub_link/Collateral/1N5817-D.PDF

The reason is that if the answering machine draws 200mA all the time
and the wall-wart is designed to output 12V under that load, then
there'll only be about 11.7V at the cathode of the leftmost diode to
charge the battery.

Linear wall-warts argent usually that well regulated though:

http://204.202.11.159/tamuracorp/clientuploads/pdfs/engineeringdocs/318AS12030.pdf

so if the answering machine uses less current when it's idling, then
the wall-wart's output voltage will rise and battery to a higher
voltage during that time.

Please bottom post.

JF

 

[Viel Spass]

On Aug 4, 4:37 pm, John Fields <jfie...@austininstruments.com> wrote:

On Mon, 4 Aug 2008 12:06:43 -0700 (PDT), Viel Spass

andy77...@yahoo.com> wrote:
I am looking for some ideas. I have an answering machine runnning off
a 12 VDC transformer.

---
There is no such thing; you must be referring to an AC to DC
wall-wart, yes?
---

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

---
You can.
Do you have any test equipment?

Assuming your answering machine doesn't draw 200 mA all the time, why
not use a sealed lead-acid battery and a couple of Schottky diodes
instead and use your wall-wart to charge the battery and run the
answering machine at the same time?

Then when the mains go down, battery power will be steered into the
answering machine seamlessly and the answering machine will stay on
for as long as the battery can keep it on.

That's a 12V UPS.

View in Courier:

WALL ANS.
WART MACH
+----+ +----+
MAINS>--|~ +|--[1N5817>]-+-[1N5817>]--|+ |
| | |+ | |
| } [BAT] | |
| | | | |
MAINS>--|~ -|------------+------------|- |
+----+ +----+

JF

By transformer, I mean that it reduces 120V to 12DC.
What would a 12V sealed battery run ?

Are the diodes or rectifiers used to smooth out the DC output ?

I was also thinking of using NiMh batteries as an alternative.
Making a charger should be too big a deal.

Andy

 

On Aug 4, 2:37 pm, John Fields <jfie...@austininstruments.com> wrote:

On Mon, 4 Aug 2008 12:06:43 -0700 (PDT), Viel Spass

andy77...@yahoo.com> wrote:
I am looking for some ideas. I have an answering machine runnning off
a 12 VDC transformer.

---
There is no such thing; you must be referring to an AC to DC
wall-wart, yes?
---

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

---
You can.
Do you have any test equipment?

Assuming your answering machine doesn't draw 200 mA all the time, why
not use a sealed lead-acid battery and a couple of Schottky diodes
instead and use your wall-wart to charge the battery and run the
answering machine at the same time?

Then when the mains go down, battery power will be steered into the
answering machine seamlessly and the answering machine will stay on
for as long as the battery can keep it on.

That's a 12V UPS.

View in Courier:

WALL ANS.
WART MACH
+----+ +----+
MAINS>--|~ +|--[1N5817>]-+-[1N5817>]--|+ |
| | |+ | |
| } [BAT] | |
| | | | |
MAINS>--|~ -|------------+------------|- |
+----+ +----+

JF

Maybe I'm missing something here, but I thought the minimum float
voltage for an SLA is 2.25V per cell, to avoid irreversible damage
from sulfation. That's 13.5V for a 12V nominal, 6-cell battery. But,
13.5V could cook his answering machine.

http://www.batteryuniversity.com/partone-13.htm

???

Michael

 

[Viel Spass]

On Aug 7, 3:06 am, mrdarr...@gmail.com wrote:

On Aug 4, 2:37 pm, John Fields <jfie...@austininstruments.com> wrote:



On Mon, 4 Aug 2008 12:06:43 -0700 (PDT), Viel Spass

andy77...@yahoo.com> wrote:
I am looking for some ideas. I have an answering machine runnning off
a 12 VDC transformer.

---
There is no such thing; you must be referring to an AC to DC
wall-wart, yes?
---

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

---
You can.
Do you have any test equipment?

Assuming your answering machine doesn't draw 200 mA all the time, why
not use a sealed lead-acid battery and a couple of Schottky diodes
instead and use your wall-wart to charge the battery and run the
answering machine at the same time?

Then when the mains go down, battery power will be steered into the
answering machine seamlessly and the answering machine will stay on
for as long as the battery can keep it on.

That's a 12V UPS.

View in Courier:

WALL ANS.
WART MACH
+----+ +----+
MAINS>--|~ +|--[1N5817>]-+-[1N5817>]--|+ |
| | |+ | |
| } [BAT] | |
| | | | |
MAINS>--|~ -|------------+------------|- |
+----+ +----+

JF

Maybe I'm missing something here, but I thought the minimum float
voltage for an SLA is 2.25V per cell, to avoid irreversible damage
from sulfation. That's 13.5V for a 12V nominal, 6-cell battery. But,
13.5V could cook his answering machine.

http://www.batteryuniversity.com/partone-13.htm

???

Michael

Couldn't I use some Zener diodes to keep the voltage at 12.0 on the
ouput?

Andy

 

[Jasen Betts]

On 2008-08-04, Viel Spass <andy77017@yahoo.com> wrote:

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

basically it's a 12V battery connected to a charger.

messing with the power-supplies of phone eqipment is frowned upon by
many authorities, and you may be in for a surprise if you're touching one
of the conductors when the phone rings.

Bye.
Jasen

 

[Viel Spass]

On Aug 7, 8:29 am, "Tom Biasi" <tombiasi...@optonline.net> wrote:

"Viel Spass" <andy77...@yahoo.com> wrote in message

news:c71ab56e-ebb2-4f40-aadc-06214f00e933@d45g2000hsc.googlegroups.com...



On Aug 7, 3:06 am, mrdarr...@gmail.com wrote:
On Aug 4, 2:37 pm, John Fields <jfie...@austininstruments.com> wrote:

On Mon, 4 Aug 2008 12:06:43 -0700 (PDT), Viel Spass

andy77...@yahoo.com> wrote:
I am looking for some ideas. I have an answering machine runnning off
a 12 VDC transformer.

---
There is no such thing; you must be referring to an AC to DC
wall-wart, yes?
---

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

---
You can.
Do you have any test equipment?

Assuming your answering machine doesn't draw 200 mA all the time, why
not use a sealed lead-acid battery and a couple of Schottky diodes
instead and use your wall-wart to charge the battery and run the
answering machine at the same time?

Then when the mains go down, battery power will be steered into the
answering machine seamlessly and the answering machine will stay on
for as long as the battery can keep it on.

That's a 12V UPS.

View in Courier:

WALL ANS.
WART MACH
+----+ +----+
MAINS>--|~ +|--[1N5817>]-+-[1N5817>]--|+ |
| | |+ | |
| } [BAT] | |
| | | | |
MAINS>--|~ -|------------+------------|- |
+----+ +----+

JF

Maybe I'm missing something here, but I thought the minimum float
voltage for an SLA is 2.25V per cell, to avoid irreversible damage
from sulfation. That's 13.5V for a 12V nominal, 6-cell battery. But,
13.5V could cook his answering machine.

http://www.batteryuniversity.com/partone-13.htm

???

Michael

Couldn't I use some Zener diodes to keep the voltage at 12.0 on the
ouput?

Andy

For the last time. All you need is a battery and a charger.

You didn't answer my question, just complained.

 

[Charlie Siegrist]

On Tue, 05 Aug 2008 18:46:47 -0700, Viel Spass wrote:

<snipped diagram, can't figure out how to make Pan behave itself>

By transformer, I mean that it reduces 120V to 12DC. What would a 12V
sealed battery run ?

Yes, he knew what you meant. His reply was meant to tell you that
changing 120VAC to 12VDC cannot be done with just a transformer. A
transformer will change one value of AC to another value of AC, but will
not change AC to DC. AC to DC requires a transformer plus a rectifier,
and depending on the application, a filter.

 

[Charlie Siegrist]

On Thu, 07 Aug 2008 06:18:15 -0700, Viel Spass wrote:

Maybe I'm missing something here, but I thought the minimum float
voltage for an SLA is 2.25V per cell, to avoid irreversible damage from
sulfation. That's 13.5V for a 12V nominal, 6-cell battery. But, 13.5V
could cook his answering machine.

http://www.batteryuniversity.com/partone-13.htm

???

Michael

Couldn't I use some Zener diodes to keep the voltage at 12.0 on the
ouput?

Michael is correct, if you use a sealed lead-acid battery, you will need
to run your battery charger at a proper float voltage, which has to be
regulated. It can be too high or too low and the battery will be
damaged. You will have to regulate the voltage at the answering machine
to within its rated tolerence. You will have an idle load and a full
load, and will need to know both values. If the high load is for short
durations only, the charger as set up properly will handle it, you'll be
off float for short enough periods. NimH batteries have their own
idosyncracies, as has been mentioned.

I know you think that Tom is complaining, but do you really want to
design your own UPS, or do you just want to have a way to keep your
answering machine from turning off during a power outage? Here's an
idea, buy an UPS for your computer gear and plug the answering machine
into it!

 

[Viel Spass]

On Aug 9, 1:08 am, Charlie Siegrist
<none.act...@this.time.check.back.later> wrote:

On Tue, 05 Aug 2008 18:46:47 -0700, Viel Spass wrote:

snipped diagram, can't figure out how to make Pan behave itself

By transformer, I mean that it reduces 120V to 12DC. What would a 12V
sealed battery run ?

Yes, he knew what you meant. His reply was meant to tell you that
changing 120VAC to 12VDC cannot be done with just a transformer. A
transformer will change one value of AC to another value of AC, but will
not change AC to DC. AC to DC requires a transformer plus a rectifier,
and depending on the application, a filter.

I have been doing electronic work for a number of years but am a
little rusty.
That's why I ask a lot of questions.

Andy

 

[Viel Spass]

On Aug 9, 1:22 am, Charlie Siegrist
<none.act...@this.time.check.back.later> wrote:

On Thu, 07 Aug 2008 06:18:15 -0700, Viel Spass wrote:
Maybe I'm missing something here, but I thought the minimum float
voltage for an SLA is 2.25V per cell, to avoid irreversible damage from
sulfation. That's 13.5V for a 12V nominal, 6-cell battery. But, 13.5V
could cook his answering machine.

I know you think that Tom is complaining, but do you really want to
design your own UPS, or do you just want to have a way to keep your
answering machine from turning off during a power outage? Here's an
idea, buy an UPS for your computer gear and plug the answering machine
into it!

That is one way. My experience with UPS is the batteries don't last
very long for the cost involved.
I will go with a SLA and figure the idle and float load in order to
make a basic charger for it.

Thanks.

 

[Charlie Siegrist]

On Sat, 09 Aug 2008 04:52:42 -0700, Viel Spass wrote:

That is one way. My experience with UPS is the batteries don't last very
long for the cost involved.
I will go with a SLA and figure the idle and float load in order to make
a basic charger for it.

Well, you're right about that, a typical UPS battery will only last two
years or so, whereas an SLA could last up to ten years or more, depending
on use and care. You should read up on the subject of batteries and
battery systems, lead-acid in particular. I notice you said "...figure
idle and float...." What you may not know is that idle and float, in the
context, are the same thing. When the load is idle, the battery should
be at float voltage. There are three basic modes for a UPS battery:
float, equalize, and emergency load. Enjoy your reading!

 

[Charlie Siegrist]

On Fri, 08 Aug 2008 10:07:31 +0000, Jasen Betts wrote:

On 2008-08-04, Viel Spass <andy77017@yahoo.com> wrote:

Whenever power goes out, I have to turn it back on. (Recording is still
kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries? Do they make a 12 volt UPS ?

basically it's a 12V battery connected to a charger.

messing with the power-supplies of phone eqipment is frowned upon by
many authorities, and you may be in for a surprise if you're touching
one of the conductors when the phone rings.

I'm not sure I understand your response. The original poster is
discussing a 12VDC supply to an answering machine via a plug-in
rectifying transformer. Please explain the danger of ring voltage
somehow appearing via the recitified AC voltage from a wall outlet?

And by all means, have the "authorities" contact me if they have
questions.

 

[Jasen Betts]

On 2008-08-13, Charlie Siegrist <none.active@this.time.check.back.later> wrote:

On Fri, 08 Aug 2008 10:07:31 +0000, Jasen Betts wrote:

On 2008-08-04, Viel Spass <andy77017@yahoo.com> wrote:

Whenever power goes out, I have to turn it back on. (Recording is still
kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries? Do they make a 12 volt UPS ?

basically it's a 12V battery connected to a charger.

messing with the power-supplies of phone eqipment is frowned upon by
many authorities, and you may be in for a surprise if you're touching
one of the conductors when the phone rings.

I'm not sure I understand your response. The original poster is
discussing a 12VDC supply to an answering machine via a plug-in
rectifying transformer. Please explain the danger of ring voltage
somehow appearing via the recitified AC voltage from a wall outlet?

Possibly the 0V DC input terminal of the device is connected directly
to one of the phone line wires. I've seen many answering machines
bearing a label that reads something like "use only with with [insert
phone authority here] approved power supply"

Bye.
Jasen

 

[Viel Spass]

On Aug 8, 5:07 am, Jasen Betts <ja...@xnet.co.nz> wrote:

On 2008-08-04, Viel Spass <andy77...@yahoo.com> wrote:

Whenever power goes out, I have to turn it back on. (Recording is
still kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries?
Do they make a 12 volt UPS ?

basically it's a 12V battery connected to a charger.

messing with the power-supplies of phone eqipment is frowned upon by
many authorities, and you may be in for a surprise if you're touching one
of the conductors when the phone rings.

Bye.
Jasen

How you came up with messing with the phone line is a big mystery.

Maybe you have used the 30-60 Volts to power something ?
That is called theft of service.

 

[Viel Spass]

On Aug 14, 5:13 am, Jasen Betts <ja...@xnet.co.nz> wrote:

On 2008-08-13, Charlie Siegrist <none.act...@this.time.check.back.later> wrote:



On Fri, 08 Aug 2008 10:07:31 +0000, Jasen Betts wrote:

On 2008-08-04, Viel Spass <andy77...@yahoo.com> wrote:

Whenever power goes out, I have to turn it back on. (Recording is still
kept)

It draws 200 ma of current which I calculate to be V x A = 6 watts.

Could I use 8 D size 1.5 V batteries? Do they make a 12 volt UPS ?

basically it's a 12V battery connected to a charger.

messing with the power-supplies of phone eqipment is frowned upon by
many authorities, and you may be in for a surprise if you're touching
one of the conductors when the phone rings.

I'm not sure I understand your response. The original poster is
discussing a 12VDC supply to an answering machine via a plug-in
rectifying transformer. Please explain the danger of ring voltage
somehow appearing via the recitified AC voltage from a wall outlet?

Possibly the 0V DC input terminal of the device is connected directly
to one of the phone line wires. I've seen many answering machines
bearing a label that reads something like "use only with with [insert
phone authority here] approved power supply"

Bye.
Jasen

I have looked at many answering machine and never see such a label.

The only requirments are that it conforms to Part 68 FCC rules.

Outta here.

 

[Charlie Siegrist]

On Thu, 14 Aug 2008 10:13:41 +0000, Jasen Betts wrote:

I'm not sure I understand your response. The original poster is
discussing a 12VDC supply to an answering machine via a plug-in
rectifying transformer. Please explain the danger of ring voltage
somehow appearing via the recitified AC voltage from a wall outlet?

Possibly the 0V DC input terminal of the device is connected directly to
one of the phone line wires.

Can you explain how such a design would function? I'm eager to hear.

I've seen many answering machines bearing a
label that reads something like "use only with with [insert phone
authority here] approved power supply"

I don't see the relevence.

 

[Jasen Betts]

On 2008-08-15, Charlie Siegrist <none.active@this.time.check.back.later> wrote:

On Thu, 14 Aug 2008 10:13:41 +0000, Jasen Betts wrote:

I'm not sure I understand your response. The original poster is
discussing a 12VDC supply to an answering machine via a plug-in
rectifying transformer. Please explain the danger of ring voltage
somehow appearing via the recitified AC voltage from a wall outlet?

Possibly the 0V DC input terminal of the device is connected directly to
one of the phone line wires.

Can you explain how such a design would function? I'm eager to hear.

I envisage a setup something like this:

+12V
___|____
input| | output
-----------| circuit|----------._/|
|________| |_ |
phone line | | \|
---------------+---------------'
|
0V (not grounded)

You seem to be of the opinion that such a thing is unworkable.
why is that?

Bye.
Jasen

 

[Charlie Siegrist]

On Fri, 15 Aug 2008 11:29:15 +0000, Jasen Betts wrote:

On 2008-08-15, Charlie Siegrist <none.active@this.time.check.back.later
wrote:
On Thu, 14 Aug 2008 10:13:41 +0000, Jasen Betts wrote:

I'm not sure I understand your response. The original poster is
discussing a 12VDC supply to an answering machine via a plug-in
rectifying transformer. Please explain the danger of ring voltage
somehow appearing via the recitified AC voltage from a wall outlet?

Possibly the 0V DC input terminal of the device is connected directly
to one of the phone line wires.

Can you explain how such a design would function? I'm eager to hear.

I envisage a setup something like this:

+12V
___|____
input| | output
-----------| circuit|----------._/|
|________| |_ |
phone line | | \|
---------------+---------------'
|
0V (not grounded)

You seem to be of the opinion that such a thing is unworkable. why is
that?

You are correct in that assessment. I think it would be more to the
point that you showed me that it could work. Let's start out with a
simple question. In your drawing, which is tip and which is ring?