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 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.

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.

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

"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!

"Joe Analssandrini" wrote in message
ups.com...
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

Joe, your fond reminsinces make me realize that I may have been too harsh in
my stated opinions of the 9V battery. I don't want to give the impression
that I dislike 'em as much as I dislike -- say -- IBOC.

The lowest price I remember for the things was about 19 cents. The ones
wrapped in cellophane like a pack of cigarettes seemed to cost a few cents
more. But this was well after the fifties, when everything connected with
shirt pocket portables was still new and expensive. I've seen old Zenith
ads in which they claim that the difference in cost of replacing the
batteries in their AA penlite powered radios was enough to make up a
significant part of the increased price of their radios.

I do know that flashlight battery powered radios were cheaper to run than
transistor radio battery powered radios. We had a Silvertone radio which
would go a year between changing it's six D cells. I know that's not a fair
comparison with the 9V transistor radio battery, but the 9 volters seemed to
have a lifespan best measured in hours.

And it's not like I think the 9V battery is completely useless. I was
considering putting some LED illumination behind the dial of my
Hallicrafters TW 1000. I was concerned about the visibility of the dial
markings under the monochromatic illumination of the LEDs. So, I figured I
could take three different 9V battery snaps and LED up some red, yellow and
green flashlights. I didn't actually do it, but I did think of it. And I
also figured I could glue an opamp, deadbug style, and a tiny watch crystal
sized 100 kHz crystal, on a snap and make crystal calibrator. It works fine
on perfboard! That's not to mention the Zener diode noise generator and the
650/1300 kHz LC signal generator for peaking antenna/RF circuits. Yep, I
could have done it all on 9V snaps, but I didn't.

It's starting to look like 9V transistor radio batteries are more useful
than I am. Damn.


*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!

I'll take it you mean there's nothing better -- on a bike.

Frank Dresser

Joe Analssandrini wrote:

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

I manage to get carbon-zinc 9-volt batts - either Eveready or Panasonic
in two-for-a-dollar packs at all the "Dollar Stores" here..

Of course, I can also get 4-packs of AA cells for a dollar (C-Zn also)
but I usually buy alkalines from Ikea Furniture, which comes out
cheaper.

9-volt alkalines are outrageously priced though. Almost $3 or $4.00 per
BATTERY? What the hell?

Radios work fine with a Carbon-Zinc battery though.

--
Steph