Searching \ for 'Battery Power Supply?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: massmind.org/techref/power/batterys.htm?key=battery
Search entire site for: 'Battery Power Supply?'.

Truncated match.
PICList Thread
'Battery Power Supply?'
1999\06\25@042757 by Stewart Pye

flavicon
face
Hi All...

I'm doing a project with a PIC16F84 that I want to run from batteries. The
person I'm doing it for would prefer to use a 9V battery. My question is:

Should I use a 78L05 regulator, or resistor voltage divider, or
resistor/zener diode?
Which one would consume the least current. I'm guessing a 78L05 would be
the way to go. Any Ideas?


Thanks,
Stewart.

1999\06\25@065641 by Caisson

flavicon
face
> Van: Stewart Pye <spam_OUTstewTakeThisOuTspamUQ.NET.AU>
> Aan: .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
> Onderwerp: Battery Power Supply?
> Datum: vrijdag 25 juni 1999 10:30
>
> Hi All...

Hello Stewart,

> I'm doing a project with a PIC16F84 that I want to run from batteries.
The
> person I'm doing it for would prefer to use a 9V battery. My question is:
>
> Should I use a 78L05 regulator, or resistor voltage divider, or
> resistor/zener diode?
> Which one would consume the least current. I'm guessing a 78L05 would be
> the way to go. Any Ideas?

Not a good idea.  Your 78L05 would consume about 4 to 5000 ! times the
current the PIC would take.  A PIC run's well on 3 volts.  Why not take 2
penlights, put them together in a case with contacts on top like a 9 volt
block (available in any electronics store) and use them like you would a 9
volt block ...

Greetz,
 Rudy Wieser

1999\06\25@075059 by Joe McCauley

picon face
At 13:01 25/06/99 +0200, you wrote:
{Quote hidden}

Also not such a great idea. Unless the contacts and the package are totally
different
from a 9V battery, you can be sure that sooner or later someone will try to
fit
a 9 Volt battery into it.

Linear Technology make what they call Micropower switching regulators (LT1073)
They cost IR£5 in single quantities according to my Farnell catalog. I've
never used them so I don't know what the quiescent current consumption is.  

Joe

1999\06\25@080759 by paulb

flavicon
face
Stewart Pye wrote:

> Should I use a 78L05 regulator, or resistor voltage divider, or
> resistor/zener diode?

 Well, the last one (called a "shunt regulator") is *awful* for a
couple of reasons.  One is that it *always* draws the maximum current,
the other is that the maximum current available is limited by the input
voltage, which is the way you don't want things to be.  Forget that.

 Resistors are even worse, because they wouldn't even regulate the
voltage as either the battery voltage or the load current varied.

> Which one would consume the least current. I'm guessing a 78L05 would
> be the way to go. Any Ideas?

 It's been mentioned that the 78L05 has a 5 mA excitation current
leaking out the reference terminal, which is likely a *lot* more than
the average PIC consumption.  For an LM317, this is more like 50 to 100
µA though you generally need to "swamp" this in a resistive divider
drawing say, 500 µA.  These are dirt common devices.

 You can get low-power and micropower regulators which are then limited
by their *maximum* output current and tend to have significant drop-out
voltage, but there probably is one suitable for this job (others may
offer examples).

 The suggestion made to use a 3V or indeed, 4.5V battery of 2 or three
cells makes a lot of sense since these have *much* greater capacity than
9V ones.
--
 Cheers,
       Paul B.

1999\06\25@081628 by Tim Hamel

picon face
I'm usually preplexed by electronics questions, but I have a suggestion.  I
came across an LM317L.  The output current is 100mA.  It's in an SO8 package.
Could this work?

Just a suggestion,

Tim H.


In a message dated 6/25/99 5:08:11 AM Pacific Daylight Time,
EraseMEpaulbspam_OUTspamTakeThisOuTmidcoast.com.au writes:

> It's been mentioned that the 78L05 has a 5 mA excitation current
>  leaking out the reference terminal, which is likely a *lot* more than
>  the average PIC consumption.  For an LM317, this is more like 50 to 100
>  µA though you generally need to "swamp" this in a resistive divider
>  drawing say, 500 µA.  These are dirt common devices.

1999\06\25@104209 by Wagner Lipnharski

picon face
Don't forget to take a look at those Wireless Telephone Rechargeable
battery packs... they come in three round cells, packed in shrinked
plastic, and other formats like three 1/2 size AAA cells, or other. They
are easy to find  for replacement (Radio Shack has all of them for less
than $3 I think) and don't cost so much, it uses a small connector,
impossible to do mistakes.  3 Cells would generate an average of 3.4V
with aprox 150mAh (or more).
Wagner

1999\06\25@131837 by William K. Borsum

flavicon
face
At 06:30 PM 6/25/99 +1000, you wrote:
>Hi All...
>
>I'm doing a project with a PIC16F84 that I want to run from batteries. The
>person I'm doing it for would prefer to use a 9V battery. My question is:
>
>Should I use a 78L05 regulator, or resistor voltage divider, or
>resistor/zener diode?
>Which one would consume the least current. I'm guessing a 78L05 would be
>the way to go. Any Ideas?

NO question on this; TELCOM TC55 series.  Available from Digikey.
I've got two on a board, with a total quiescent current of <3 uA out the
ground pin with no load.  <100mV drop out at low loads, and CHEAP.

Kelly

****************************************************************************
********
All legitimate attachments to this email will be clearly identified in the
text.
William K. Borsum, P.E.
OEM Dataloggers and Instrumentation Systems
<borsumspamspam_OUTdascor.com> & <http://www.dascor.com>

1999\06\25@133506 by Rock Thompson

picon face
I'm doing the same thing and have decided to use the MAX639.  It is
very efficient and uses an incredibly same amount of current.  Combine
it with a 9V lithium battery for twice the capacity of an alkaline.  As
usual, the only disadvantage is cost.

Rock

--- Stewart Pye <@spam@stewKILLspamspamUQ.NET.AU> wrote:
{Quote hidden}

_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com

1999\06\25@135132 by Greg Wiley

picon face
Paul B. Webster VK2BZC <KILLspampaulbKILLspamspammidcoast.com.au> wrote:

> Stewart Pye wrote:

> > Should I use a 78L05 regulator, or resistor voltage divider, or
> > resistor/zener diode?

>   You can get low-power and micropower regulators which are then limited
> by their *maximum* output current and tend to have significant drop-out
> voltage, but there probably is one suitable for this job (others may
> offer examples).

I was following the discussion just fine until this point.  Forgive my
ignorance but what is a "drop-out voltage" and why is a high one bad?

Thanks,
 -greg

1999\06\25@141455 by Wagner Lipnharski

picon face
Drop Out Voltage is how many volts (millivolts) the regulator holds
across its input and output.

Example:

Input voltage is battery 9Vdc and discharging, going down.
Regulator Dropout Voltage: 1Vdc
Regulator Output Voltage: +5Vdc
Minimum battery voltage to be regulated to +5Vdc: 6Vdc.

Consider from 0.5 to 1.0 more for safety reasons, so the minimum battery
Voltage to regulate a steady and confortable +5Vdc at output would be
7Vdc.

If using a NiCad 9V battery, in real it is 7.2V (some of them), so right
after the first use, the battery would not be in "safe voltage" to feed
a 1 Vdc dropout regulator, because its Voltage would be lower than
7Vdc...

In any case, it also means power lost, since this dropout times current
means waste of power on the regulator.
In a regular regulator that uses to reduce voltage by voltage control,
it doesn't matter so much, since it is already wasting power to deliver
a lower voltage, but if it is being used in a inteligent regulator with
switching power supply or some other scheme, hmmm, that power loss is
considerable...

Wagner.


Greg Wiley wrote:
{Quote hidden}

1999\06\26@023405 by Hans Blichfeldt

flavicon
face
Try Telcom TL55 type.
Good to use and consumes 1-4 uA.

Best regards,
Hans


At 06:30 PM 25/06/1999 +1000, you wrote:
{Quote hidden}

--
Temperature Technology
263 Gilbert Street
ADELAIDE  SA  5000

web page:       http://dove.net.au/~ttec
email:          spamBeGonettecspamBeGonespamdove.net.au

--

1999\06\26@230255 by Russell McMahon

picon face
I recommend the LM2936 regulator for low current consumption
applications. This supplies  a maximum current of about 50ma but has
a quiescent current of around 10 microamp actual (data book may say a
bit more - certainly under 50 uA). Using one of these alone a 9v
battery would last for its shelf life.

Same TO92 package as a 78L05. They are dearer but not excessively so
unless your project is very price critical. I use two of these in
parallel in a commercial product that I make because they did better
than anything else I could find when I designed it.



{Original Message removed}

1999\06\27@184311 by John Duncan

picon face
Stewart

If you need a 5 V supply from a 9 V batt, try the Nat Semi LM2936.
Microzed stock them.  I think they are used in the Basic Stamp chip set
that they sell.  I bought some a few months ago.  About $1.40.

Cheers
JD

1999\06\28@012449 by Robert K. Johnson

flavicon
face
At 12:59 PM 6/26/99 +1200, you wrote:
>I recommend the LM2936 regulator for low current consumption
>applications. This supplies  a maximum current of about 50ma but has
>a quiescent current of around 10 microamp actual (data book may say a
>bit more - certainly under 50 uA). Using one of these alone a 9v
>battery would last for its shelf life.
       One might investigate the specifications of the Maxin MAX666 or MAX 667
Seems to me that they draw about 6 to 8 µA under all conditions. (MAX I/Q
13 µA)
       Most if not all "low I/Q" regulators  draw considerable current when the
output current goes beyond a 100 or so µA, Typically about 5 to 10% of the
load current. For example the LM2936 draws 1.5 ma quiesent current at a 50
ma load. This taken from the NSD power databook 1993 release date.
>Same TO92 package as a 78L05. They are dearer but not excessively so
>unless your project is very price critical. I use two of these in
>parallel in a commercial product that I make because they did better
>than anything else I could find when I designed it.
>
>
>
>{Original Message removed}

1999\06\28@095813 by sbb.simpeltron

flavicon
face
Why not a zener in series?
I used a 3.6 V zener in series with a PIC12C508 to reduce the voltage of a
9V battery.
Low cost, no quiescent current and works perfect.
The PIC drives three pairs of LED's in series, directly connected to the
battery, a seventh single led is connected to the zener.
It works until the battery voltage has dropped to 6V.

Leo van Loon
SBB simpeltronics
Netherlands
tel +31 (0481) 450034
fax+31 (0481) 450051
mail TakeThisOuTsbb.simpeltronEraseMEspamspam_OUTtip.nl
url http://www.sbb-simpeltronics.nl
SBB simpeltronics ontwikkelt technische projecten voor basisschool en
basisvorming.
SBB simpeltronics develops technical projects for children in primary and
secondary education.

More... (looser matching)
- Last day of these posts
- In 1999 , 2000 only
- Today
- New search...