Getting 5VDC from a 9 volt battery

P

PIC

Guest
Hi,

Is there an easy, efficient, and low cost way to get 5VDC to power a
microcontroller (PIC16F77) from a standard 9 volt battery? If you need more
information, please feel free to ask.

Thanks in advance,
Joe
 
PIC wrote:
Hi,

Is there an easy, efficient, and low cost way to get 5VDC to power a
microcontroller (PIC16F77) from a standard 9 volt battery? If you need more
information, please feel free to ask.

Thanks in advance,
Joe
Click to expand...
The simplest would be a linear regulator. The NPN output types are
most stable, but waste a bit more power and need about 1.5 volts above
the 5 volt output to work.

Here is a list of all those made by National Semiconductor:
http://www.national.com/parametric/0,,648,00.html

A good candidate for a PIC and very little else (low current) might be
the LM340LAZ-5.0 or the LM78L05. Both are good for 100 ma out, which
is more than you can say for a 9 volt battery.

The low drop out types are listed here:
http://www.national.com/parametric/0,1850,663-c14-0,00.html

They work till the battery gets very close ot 5 volts, so they last a
bit longer (but not much, since a 9 volt battery goes down very
quickly once it reaches 7 volts).
The LM2936-5.0 is good for up to 50 ma.
The LM2931 series are good for 100 ma.
The low drop out types are also more particular about capacitor
filtering to remain stable than the NPN output types, so unless you
have a scope to verify that they are not oscillating, I recommend you
go with a low current version from the first list.

The data sheets for all these are available from these lists, so you
can review all the particulars.

--
John Popelish
 
In article <36cc539f.0402051802.cdbbe6@posting.google.com>,
joesrockets@yahoo.com (PIC) wrote:

Hi,

Is there an easy, efficient, and low cost way to get 5VDC to power a
microcontroller (PIC16F77) from a standard 9 volt battery? If you need more
information, please feel free to ask.

Thanks in advance,
Joe
Click to expand...
A 7805 voltage regulator mounted on a hefty heat-sink is probably the
simplest and cheapest, but I'd expect it to chow on batteries like
they're being outlawed tomorrow.

This is one of those classic "You have three options: Easy, Cheap, and
Efficient. You may choose any two of them" situations. You want easy and
cheap, you gotta give up efficient. You want efficient, figure out which
of easy and cheap is more important to you and kiss off the other one.

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
On Thu, 05 Feb 2004 18:02:05 -0800, PIC wrote:
Is there an easy, efficient, and low cost way to get 5VDC to power a
microcontroller (PIC16F77) from a standard 9 volt battery? If you need more
information, please feel free to ask.
Click to expand...
I know very little about electronics, but I successfuly
built this gaussmeter which is stupidly simply to build
and it drops a 9V transistor battery to 5V DC using a
cheap simple voltage regulator.
http://my.execpc.com/~rhoadley/magmeter.htm
 
In article <36cc539f.0402051802.cdbbe6@posting.google.com>,
PIC <joesrockets@yahoo.com> wrote:
-Hi,
-
-Is there an easy, efficient, and low cost way to get 5VDC to power a
-microcontroller (PIC16F77) from a standard 9 volt battery? If you need more
-information, please feel free to ask.

I'm glad you put efficient into the equation. Simply put any linear regulator
is going to consume almost half of your already meager power budget.

You need a switching regulator. You can get 2.5 out of your 3 requirements
by using the Roman Black 2 transistor switching regulator here:

http://www.romanblack.com/smps.htm

It has nearly double the efficiency of the linear regulator and will maintain
regulator down a lower voltage, so it'll run over twice as long as the
linear regulator. It's not a single part (so only half for easy) but it is
cheap and very very efficient.

BAJ
 
Byron A Jeff wrote:

In article <36cc539f.0402051802.cdbbe6@posting.google.com>,
PIC <joesrockets@yahoo.com> wrote:
-Hi,
-
-Is there an easy, efficient, and low cost way to get 5VDC to power a
-microcontroller (PIC16F77) from a standard 9 volt battery? If you need
more -information, please feel free to ask.

I'm glad you put efficient into the equation. Simply put any linear
regulator is going to consume almost half of your already meager power
budget.

You need a switching regulator. You can get 2.5 out of your 3 requirements
by using the Roman Black 2 transistor switching regulator here:

http://www.romanblack.com/smps.htm

It has nearly double the efficiency of the linear regulator and will
maintain regulator down a lower voltage, so it'll run over twice as long
as the linear regulator. It's not a single part (so only half for easy)
but it is cheap and very very efficient.

BAJ
what is wrong with using 4 nicads? they add up to 4.8 volts
Click to expand...


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http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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"Byron A Jeff" <byron@cc.gatech.edu> wrote in message
news:c019s9$4d8@cleon.cc.gatech.edu...
In article <36cc539f.0402051802.cdbbe6@posting.google.com>,
PIC <joesrockets@yahoo.com> wrote:
-Hi,
-
-Is there an easy, efficient, and low cost way to get 5VDC to power a
-microcontroller (PIC16F77) from a standard 9 volt battery? If you need
more
-information, please feel free to ask.

I'm glad you put efficient into the equation. Simply put any linear
regulator
is going to consume almost half of your already meager power budget.

You need a switching regulator. You can get 2.5 out of your 3 requirements
by using the Roman Black 2 transistor switching regulator here:

http://www.romanblack.com/smps.htm

It has nearly double the efficiency of the linear regulator and will
maintain
regulator down a lower voltage, so it'll run over twice as long as the
linear regulator. It's not a single part (so only half for easy) but it is
cheap and very very efficient.

BAJ
Click to expand...
The smps you recommend is nice, but if the OP is doing any analog
measurements, the noise from the smps might interfere.

Depending on the application, its possible that a linear regulator is fine
for the tiny amounts of current required for a PIC.

Regards,
Bob Monsen
 
In article <40245fba_2@corp.newsgroups.com>,
j taylor <jctnospam@yellville.net> wrote:
-Byron A Jeff wrote:
-
-> In article <36cc539f.0402051802.cdbbe6@posting.google.com>,
-> PIC <joesrockets@yahoo.com> wrote:
-> -Hi,
-> -
-> -Is there an easy, efficient, and low cost way to get 5VDC to power a
-> -microcontroller (PIC16F77) from a standard 9 volt battery?

-> You need a switching regulator. You can get 2.5 out of your 3 requirements
-> by using the Roman Black 2 transistor switching regulator here:

-what is wrong with using 4 nicads? they add up to 4.8 volts

Nothing. However that wasn't the question asked.

BAJ
 
In article <ts%Ub.109501$U%5.568654@attbi_s03>,
Robert C Monsen <rcsurname@comcast.net> wrote:
-
-"Byron A Jeff" <byron@cc.gatech.edu> wrote in message
-news:c019s9$4d8@cleon.cc.gatech.edu...
-> In article <36cc539f.0402051802.cdbbe6@posting.google.com>,
-> PIC <joesrockets@yahoo.com> wrote:
-> -Hi,
-> -
-> -Is there an easy, efficient, and low cost way to get 5VDC to power a
-> -microcontroller (PIC16F77) from a standard 9 volt battery? If you need
-more
-> -information, please feel free to ask.
->
-> I'm glad you put efficient into the equation. Simply put any linear
-regulator
-> is going to consume almost half of your already meager power budget.
->
-> You need a switching regulator. You can get 2.5 out of your 3 requirements
-> by using the Roman Black 2 transistor switching regulator here:
->
-> http://www.romanblack.com/smps.htm
->
-> It has nearly double the efficiency of the linear regulator and will
-maintain
-> regulator down a lower voltage, so it'll run over twice as long as the
-> linear regulator. It's not a single part (so only half for easy) but it is
-> cheap and very very efficient.
->
-> BAJ
-
-The smps you recommend is nice, but if the OP is doing any analog
-measurements, the noise from the smps might interfere.

Low noise wasn't a part of the specification. Efficient was.

-
-Depending on the application, its possible that a linear regulator is fine
-for the tiny amounts of current required for a PIC.

Truthfully 9V batteries are not the best for many applications. They end up
being a string of AAAA cells, which really do not have a whole lot of power.
D cells typically have over 10 times the capacity of equivalent 9V batteries.
It may be better to think about how to take 2 D cells giving 3V and boost it
to 5V.

BAJ
 
"Byron A Jeff" <byron@cc.gatech.edu> wrote in message
news:c033vv$9jr@cleon.cc.gatech.edu...
In article <ts%Ub.109501$U%5.568654@attbi_s03>,
Robert C Monsen <rcsurname@comcast.net> wrote:
-
-"Byron A Jeff" <byron@cc.gatech.edu> wrote in message
-news:c019s9$4d8@cleon.cc.gatech.edu...
-> In article <36cc539f.0402051802.cdbbe6@posting.google.com>,
-> PIC <joesrockets@yahoo.com> wrote:
-> -Hi,
-> -
-> -Is there an easy, efficient, and low cost way to get 5VDC to power a
-> -microcontroller (PIC16F77) from a standard 9 volt battery? If you need
-more
-> -information, please feel free to ask.
-
-> I'm glad you put efficient into the equation. Simply put any linear
-regulator
-> is going to consume almost half of your already meager power budget.
-
-> You need a switching regulator. You can get 2.5 out of your 3
requirements
-> by using the Roman Black 2 transistor switching regulator here:
-
-> http://www.romanblack.com/smps.htm
-
-> It has nearly double the efficiency of the linear regulator and will
-maintain
-> regulator down a lower voltage, so it'll run over twice as long as the
-> linear regulator. It's not a single part (so only half for easy) but it
is
-> cheap and very very efficient.
-
-> BAJ
-
-The smps you recommend is nice, but if the OP is doing any analog
-measurements, the noise from the smps might interfere.

Low noise wasn't a part of the specification. Efficient was.
Click to expand...
You are right, but many folks use the PIC analog to digital converter. The
OP may not understand the noise implications of using an SMPS. I was simply
pointing out that the solution you suggested could interfere with that
possible usage.

-
-Depending on the application, its possible that a linear regulator is
fine
-for the tiny amounts of current required for a PIC.

Truthfully 9V batteries are not the best for many applications. They end
up
being a string of AAAA cells, which really do not have a whole lot of
power.
D cells typically have over 10 times the capacity of equivalent 9V
batteries.
It may be better to think about how to take 2 D cells giving 3V and boost
it
to 5V.

BAJ
Click to expand...
The nice thing about 9V batteries is that they are quite compact, and very
easy to interface with. You don't need a special battery holder, you only
need a two wire connector and a little compartment in your enclosure.

Regards
Bob Monsen
 
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