When I was little(r), almost all small portable radios used 9-volt
batteries. There were some, of course, that used AA's (or even 1 AA; I had
an am portable with 1 AA cell that we snuck into school when
something-or-other REALLY important to schoolboys was going on), but now I
don't have & don't know of any radio that uses 9V batteries.

Why were they needed in the first place? The 9-volt package has a lot more
package and a lot less mWatthrs in it. Was it because of the voltage - did
the existing solid-state tech not work so well at 3V?

On Mon, 29 May 2006 12:42:56 -0400, Mike wrote:

In article a,
"jtaylor" wrote:

Why were they needed in the first place? The 9-volt package has a lot more
package and a lot less mWatthrs in it. Was it because of the voltage - did
the existing solid-state tech not work so well at 3V?

Probably. The very first transistor radios used a 45 volt battery!

MIke


A 45v battery on the tongue would hurt.

On Mon, 29 May 2006 11:14:26 -0300, "jtaylor"
wrote:

When I was little(r), almost all small portable radios used 9-volt
batteries. There were some, of course, that used AA's (or even 1 AA; I had
an am portable with 1 AA cell that we snuck into school when
something-or-other REALLY important to schoolboys was going on), but now I
don't have & don't know of any radio that uses 9V batteries.

Why were they needed in the first place? The 9-volt package has a lot more
package and a lot less mWatthrs in it. Was it because of the voltage - did
the existing solid-state tech not work so well at 3V?

Mostly history and technology. The first transistors were germanium
point junction transistors. Germanium transistors has lower charge
carrier mobility than Silicon, and higher voltage losses across the
junction than Silicon. To get significant power, and gain, these
devices needed much higher voltages. 9 Volts also allowed
manufacturers to save some money. The speaker could be connected
directly to the output stage (no transformer), something that is hard
to do with 3 volts and a class B output stage. 9 volts is the norm for
these devices into the 1970's. So almost anything you see from the
1950's and 1960's uses 9 volts.

Michael Black wrote:
"jtaylor" ) writes:
When I was little(r), almost all small portable radios used 9-volt
batteries. There were some, of course, that used AA's (or even 1 AA; I had
an am portable with 1 AA cell that we snuck into school when
something-or-other REALLY important to schoolboys was going on), but now I
don't have & don't know of any radio that uses 9V batteries.

Why were they needed in the first place? The 9-volt package has a lot more
package and a lot less mWatthrs in it. Was it because of the voltage - did
the existing solid-state tech not work so well at 3V?


One thing to keep in mind that it's easier to get audio power out of an
audio amplifier if it runs off a higher voltage. And those old radios
were all about driving speakers. A 9volt batter gave the higher voltage,
but didn't require a bunch of AA cells that would take up far more space.
(Take apart a 9v battery, and you'll find actual cells inside, sometimes
small packs in plastic other times what look like smaller AAA cells.)

With recent products, they could go to a lower voltage because the
products are driving headphones. So that MP3 player runs off an AAA
cell because it doesn't need to provide much output power. Same
with Walkman's of twenty years ago, no speakers just headphones.

Motors needed lower voltage, forty years ago we had a lousy cheap
tape recorder that had a 9v batter for the amplifier and some C
cells for the motor, but required more power, so Walkmans and portable
CD players moved to multiple AAs.

One thing that has happened, as digital electronics has become a staple,
is they've gotten better at making devices that run at lower voltages
(alongside making things use less current). Which means that thirty
years ago, if an MP3 player had been practical, it likely would not
have been able to run off one AAA cell, but now they can.

Michael

The batteries inside a 9 volt battery are "Quad A" or AAAA batteries,
1.5 volt. There are 6 of them inside a 9 volt case.

Harold

matt weber wrote:
On Mon, 29 May 2006 11:14:26 -0300, "jtaylor"
wrote:

When I was little(r), almost all small portable radios used 9-volt
batteries. There were some, of course, that used AA's (or even 1 AA; I had
an am portable with 1 AA cell that we snuck into school when
something-or-other REALLY important to schoolboys was going on), but now I
don't have & don't know of any radio that uses 9V batteries.

Why were they needed in the first place? The 9-volt package has a lot more
package and a lot less mWatthrs in it. Was it because of the voltage - did
the existing solid-state tech not work so well at 3V?

Mostly history and technology. The first transistors were germanium
point junction transistors. Germanium transistors has lower charge
carrier mobility than Silicon, and higher voltage losses across the
junction than Silicon. To get significant power, and gain, these
devices needed much higher voltages. 9 Volts also allowed
manufacturers to save some money. The speaker could be connected
directly to the output stage (no transformer), something that is hard
to do with 3 volts and a class B output stage. 9 volts is the norm for
these devices into the 1970's. So almost anything you see from the
1950's and 1960's uses 9 volts.

You are probably closest to the truth, still 9V radios lasted well
beyond the Ge age. I think it was mostly a matter of engineering. Often
when you design low voltage circuits, it takes more transistors to do
the same function as a higher voltage circuit. For instance, a resistor
might be suitable to bias a long tail pair from a 9V source, but at 4V
(the minimum of 4 secondary cells) you would probably have to go for a
transistor current source. The same goes for load transistors replacing
high value resistors. Once transistors became integrated, they became
the cheapest component on a per item basis. A bridged power amp is
cheaper than an transformer based solution.

Two AA cells occupy less volume than a 9V, but the capacity difference
is well in favor of the AA cells. I don't have the number handy, but
the difference is in multiples, not a few percent. An AA alkaline is
about 3AHr using 1.5 to 0.5V operation. Granted, that takes a DC/DC PS
to achieve the full capacity.
http://www.solarbotics.net/library/p...s_batcomp.html
If you trust this source, they have a 9V alkaline cell at 0.595Ahr and
a AA cell at 2.85Ahr. 9*0.595=5.335 versus 3*2.85=8.55, so the ratio is
almost 2:1. That is, 2 AA cells will last twice as long as one 9V cell.
And of course, the AA cells are really cheap.

The only place a 9V cell make much sense is in a circuit where the
operating current is so low that you nearly get the shelf life of the
battery. Maybe a smoke detector is close to that criteria.

"matt weber" wrote in message
...

Mostly history and technology. The first transistors were germanium
point junction transistors. Germanium transistors has lower charge
carrier mobility than Silicon, and higher voltage losses across the
junction than Silicon. To get significant power, and gain, these
devices needed much higher voltages.

Point contact transistors were never used in consumer transistor radios.
The earliest radios used germanium junction transistors.

The typical voltage drop across a germanium junction is about a quarter
volt. A silicon junction drops from a half to three quarter volts.

9 Volts also allowed
manufacturers to save some money. The speaker could be connected
directly to the output stage (no transformer), something that is hard
to do with 3 volts and a class B output stage.

The early transistor radios used transformer output stages. Push-pull
output stages were the rule, driven by an phase split interstage
transformer.


9 volts is the norm for
these devices into the 1970's. So almost anything you see from the
1950's and 1960's uses 9 volts.

Can't disagree with that.

Frank Dresser

"jtaylor" wrote in message
et.ca...
When I was little(r), almost all small portable radios used 9-volt
batteries. There were some, of course, that used AA's (or even 1 AA; I
had
an am portable with 1 AA cell that we snuck into school when
something-or-other REALLY important to schoolboys was going on), but now I
don't have & don't know of any radio that uses 9V batteries.

Why were they needed in the first place? The 9-volt package has a lot
more
package and a lot less mWatthrs in it. Was it because of the voltage -
did
the existing solid-state tech not work so well at 3V?


When I was little(R), all of the portable radios (tubes) used 67-1/2V B
batteries plus a couple of D's.

HankG

Hello.

I always had a "soft spot" in my heart for the rectangular 9-volt
batteries as these were the norm when I got my first transistor radio -
a Realtone 6-transistor - which I thought was the absolute "cat's meow"
at the time. I used to go riding on my bicycle all over the place and I
always took this radio with me. I just couldn't imagine anything better
than to have a radio on my bike!*

The 9-volt batteries were very inexpensive. The Pep Boys, a local auto
parts store, sold them for 5 cents apiece! Later on, Radio Shack would
GIVE them away - you brought your "Radio Shack Battery Card" into the
store once a month and you could have one free battery of any of the
common sizes - AA, C, D, or 9-volt. As it took TWO months to get two
free AA's but only ONE month to get a free 9-volt, I always favored
9-volt-powered radios.

Today, I have two pocket AM-FM portables still in use - a Panasonic
Model RF-521, purchased sometime in the 1990s, which uses two AA
batteries, and a General Electric Model 7-2582D, purchased in the
1980s, and which uses the 9-volt battery. Both radios perform equally
regarding sensitivity, selectivity, and so forth, but the GE, being
slightly larger, has noticeably better sound quality.

Nowadays of course the 9-volt batteries are far more costly than two AA
batteries, though, in these radios, they seem to give equal length of
service.

I do not know if any radios are still being manufactured using 9-volt
batteries as their power supply.

I just still have my (irrational) "soft spot" for that battery!

Best,

Joe

*Today I use a Sony ICF-SW35, normally kept in my car, when I go bike
riding. I STILL can't imagine anything better than having a radio on my
bike!

FD,

"I suppose it's also possible the battery manufacturers were giving
the low end transistor radio manufacturers free batteries in order to
later sell short life, high profit replacement batteries."

Sounds like the early Smoke Detectors with thier Odd Voltage
and Big Odd Size Batterys that some times cost more then
the Smoke Detector did when new.

"The Japanese companies prefered the now familiar rectangular
battery which had a stack of 6 rectangular cells,"

This is what I remember from the 50s/60s a stack of Six Waffers
about 3/16" Thick {Rectanglar Cells} inside the 9 Volt Batteries
of that time.

~ RHF

The only place a 9V cell make much sense is in a circuit where the
operating current is so low that you nearly get the shelf life of the
battery. Maybe a smoke detector is close to that criteria.

I have a number of devices related to amateur astronomy that use the 9V
battery.

1. Red LED flashilight.
2. Telrad 1x finder device, also uses a LED
3. Equatorial platform driven by stepper motor

All work very well, and the lifetime of an alkaline 9V cell in these
applications is typically at least a year, sometimes far more. The
stepper motor that easily rotates a 160-pound telescope is the most
amazing one to me.

Bruce Jensen