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Sci.Electronics.Basics -> UPS for 12V DC ?

There are 28 messages in this thread.
You are currently looking at messages 1 to 20.


Author: Viel Spass
Date: 15:06 04-08-08


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.
Author: pimpom
Date: 15:33 04-08-08


"Viel Spass" <andy77017@yahoo.com> wrote in message
news:799fb6e7-2f35-4454-9781-a15ed2f792ff@p25g2000hsf.googlegroups.com...
>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 ?
>
Yes, subject to some conditions.
1) That your answering machine does not require a stable
regulated supply that stays very close to 12V..
2) That you have some form of automatic switchover. Connecting
the D batteries and the output of the 12V supply together will
not do. Connecting one diode each (say 1N4001) in series with the
"12 VDC transformer" and the battery stack should work, provided
that the machine does not mind the slight drop in voltage (the
diode will drop close to 1V on load).
3) That power does not remain off for too long. D cells won't
last very long at a continuous drain of 200mA. OTOH, if 200mA is
the nameplate rating on the machine, it's probably the maximum
and does not draw that much current all the time.



Author: Tom Biasi
Date: 17:19 04-08-08


"Viel Spass" <andy77017@yahoo.com> wrote in message
news:799fb6e7-2f35-4454-9781-a15ed2f792ff@p25g2000hsf.googlegroups.com...
>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.

Get a 12 volt rechargeable battery pack with a charger.
Run your device from a battery that is being charged at a greater rate than
you are using.
In event of a power failure the device doesn't know the difference.

BTW check your power calculation.



Author: John Fields
Date: 17:37 04-08-08

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
Author: Dave
Date: 13:14 05-08-08

Hi John,

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

Is that the max those diodes can use?

Dave
Google Groups: I do not see postings from GG.
I am using an account with http://www.usenet4all.se/ to weed out the
bullshit and spam. If you are responding from within Google Groups I
will not see your reply. Try usenet4all I think you will like it. It is
Usenet the way it used to be. Yes, I am THAT old! <grin>


John Fields wrote:
> WALL ANS.
> WART MACH
> +----+ +----+
> MAINS>--|~ +|--[1N5817>]-+-[1N5817>]--|+ |
> | | |+ | |
> | } [BAT] | |
> | | | | |
> MAINS>--|~ -|------------+------------|- |
> +----+ +----+
>
> JF
Author: John Fields
Date: 16:43 05-08-08

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
Author: Viel Spass
Date: 21:46 05-08-08

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
Author: Tom Biasi
Date: 12:59 06-08-08


"Viel Spass" <andy77017@yahoo.com> wrote in message
news:6ccd2ded-81ff-42cb-9e8e-24f35a639f42@d45g2000hsc.googlegroups.com...
> 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
>

NiMH batteries require precise charging. They are not very forgiving. ( Look
up the laptop battery recall. )
Lead acid or NiCads would be better.
As I said in my first post to you, all you need is a battery with a charger.

Tom



Date: 04:06 07-08-08

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
Author: Viel Spass
Date: 09:18 07-08-08

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
Author: Tom Biasi
Date: 09:29 07-08-08


"Viel Spass" <andy77017@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.
Author: Jasen Betts
Date: 06:07 08-08-08

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
Author: Viel Spass
Date: 19:21 08-08-08

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.
Author: Tom Biasi
Date: 20:37 08-08-08


"Viel Spass" <andy77017@yahoo.com> wrote in message
news:77710b2d-6f07-4ce7-af58-76127d82b70f@v57g2000hse.googlegroups.com...
> 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.
>
Sorry it sounded like complaining, you received several replies that
essentially said the same thing that I did but you didn't seem to care.
Best Regards,
Tom



Author: Charlie Siegrist
Date: 02:08 09-08-08

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.
Author: Charlie Siegrist
Date: 02:22 09-08-08

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!
Author: Viel Spass
Date: 07:47 09-08-08

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
Author: Viel Spass
Date: 07:52 09-08-08

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.
Author: Charlie Siegrist
Date: 09:07 11-08-08

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!
Author: Charlie Siegrist
Date: 19:41 13-08-08

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.
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