Why did so many early / cheap calculators use 9V batteries?

[Gene]

Been thinking about this for a while. Why use 9V?

Thoughts?


Links for (possibly) useful information:

Wiki on 9V: Link

Batteries: Why use 9V? Link

[Paul Berger (Canada)]

I suspect it was because of the compact size and the convenient voltage. For instance all of the Commodore calculators I have that use rechargeable batteries has a DC-DC convertor in them to boost the battery voltage whereas the one powered by a 9V battery does not, which results in lower parts count and lower cost.

[KF6GPE]

I had always assumed --- and maybe someone with an EE can tell me I'm wrong --- that the 9V was easily downconverted to 5V for TTL, and during that period TTL was cheaper than CMOS, which was newer. Getting to 5V with AA's or other batteries would require four, which is more bulk.

But that's just speculation on my part.

[Paul Berger (Canada)]

(03-29-2018 05:32 PM)KF6GPE Wrote:  I had always assumed --- and maybe someone with an EE can tell me I'm wrong --- that the 9V was easily downconverted to 5V for TTL, and during that period TTL was cheaper than CMOS, which was newer. Getting to 5V with AA's or other batteries would require four, which is more bulk.

But that's just speculation on my part.

Most of the early handhelds where mainly MOS components often PMOS, bipolar like TTL would have been too power hungry. Some may have bipolar drivers for the LED display.

Paul.

[Maximilian Hohmann]

Hello,

my guess would be that it is just for small size and low weight that manufacturers chose 9V batteries. Also I remember that in the 1970ies 9V batteries used to be cheaper then the alternative of 3 to 5 AA (alkaline) cells.

None of the older calculators (like Ti Datamath, Aristo M27, HP-35, Bowmar brain, Canon Pocketronic...) in my collection uses a 9V battery. They all have either AA batteries (4 or 5 of them) or a rechargeable pack.

Regards
Max

[Dieter]

(03-29-2018 05:32 PM)KF6GPE Wrote:  Getting to 5V with AA's or other batteries would require four, which is more bulk.

(03-29-2018 06:23 PM)Maximilian Hohmann Wrote:  my guess would be that it is just for small size and low weight that manufacturers chose 9V batteries. Also I remember that in the 1970ies 9V batteries used to be cheaper then the alternative of 3 to 5 AA (alkaline) cells.

All this is true if you compare a 9V battery with four AAs. But it's not if you look at AAA cells. Four of these have quite exactly the same volume as one 9V, and they can be arranged in different ways: 2x3 or 1x4, or even 3+1 (remember the battery holders for some 1980's cameras?). AAAs even offer more energy.

Dieter

[Maximilian Hohmann]

(03-29-2018 07:03 PM)Dieter Wrote:  But it's not if you look at AAA cells.

In my recollection of the 1970ies and 1980ies AAA cells were almost nonexistent. You needed to go to a camera store and buy them at 3 or 4 German Mark a piece (or 2000 Italian Lire as I lived in Italy then). The usual places where one went to buy batteries did not have them. 4,5V "flat batteries" yes, because they were common for flashlights, but AAA I don't remember at all. And I never owned anything that needed AAA cells then. My grandmother had a calculator "Triumph/Adler Lady" with these batteries, but that must have been in the very late 70ies, and it was the first time I ever saw this kind of battery.

[Massimo Gnerucci]

(03-29-2018 07:34 PM)Maximilian Hohmann Wrote:  

(03-29-2018 07:03 PM)Dieter Wrote:  But it's not if you look at AAA cells.

In my recollection of the 1970ies and 1980ies AAA cells were almost nonexistent. You needed to go to a camera store and buy them at 3 or 4 German Mark a piece (or 2000 Italian Lire as I lived in Italy then). The usual places where one went to buy batteries did not have them. 4,5V "flat batteries" yes, because they were common for flashlights, but AAA I don't remember at all. And I never owned anything that needed AAA cells then. My grandmother had a calculator "Triumph/Adler Lady" with these batteries, but that must have been in the very late 70ies, and it was the first time I ever saw this kind of battery.

These are also my recollections from the same time period, in the same country.

[Bill (Smithville NJ)]

(03-29-2018 06:23 PM)Maximilian Hohmann Wrote:  my guess would be that it is just for small size and low weight that manufacturers chose 9V batteries. Also I remember that in the 1970ies 9V batteries used to be cheaper then the alternative of 3 to 5 AA (alkaline) cells.

9 Volt Batteries were very cheap here in the states. I can remember buying them for 9 cents for use in my transistor radios. The batteries did not last very long, but they were cheap.

Even cheaper was belonging to the Radio Shack battery of the month club. You got one free battery every month. So if the 9 volt battery powered it for a month, then your batteries were free!

Bill
Smithville, NJ

[Dieter]

(03-29-2018 07:34 PM)Maximilian Hohmann Wrote:  In my recollection of the 1970ies and 1980ies AAA cells were almost nonexistent. You needed to go to a camera store and buy them at 3 or 4 German Mark a piece (or 2000 Italian Lire as I lived in Italy then).

These are remarkable memories. As a matter of fact, I really used to buy all my batteries in camera stores (and I still do). ;-) First, because I needed most of them for cameras, motor drives and flashguns, and finally you could be sure to get fresh and high quality batteries there.

I remember that around 1980 the usual price for a high quality AA cell over here was about 2 DEM. One store in town had a "permanent special offer" and sold regular Duracell AAs for 1 DEM. I don't remember the price for AAAs, but now I got curious. So I had a look at the 1979/80 catalog of a German mail order photo store. Surprise: a pack of four Alkaline (Duracell) AA or AAAs was 5,95 DEM, and one 9V battery had the same price.

So indeed this seems to be a topic where "your mileage may vary".

Dieter

[Thomas Okken]

(03-29-2018 07:34 PM)Maximilian Hohmann Wrote:  

(03-29-2018 07:03 PM)Dieter Wrote:  But it's not if you look at AAA cells.

In my recollection of the 1970ies and 1980ies AAA cells were almost nonexistent. You needed to go to a camera store and buy them at 3 or 4 German Mark a piece (or 2000 Italian Lire as I lived in Italy then). The usual places where one went to buy batteries did not have them. 4,5V "flat batteries" yes, because they were common for flashlights, but AAA I don't remember at all. And I never owned anything that needed AAA cells then. My grandmother had a calculator "Triumph/Adler Lady" with these batteries, but that must have been in the very late 70ies, and it was the first time I ever saw this kind of battery.

In 1976 or thereabouts, I had a Sinclair Scientific, which ran on four AAA cells. That was hideously expensive, especially for a kid with a modest allowance. Eventually I switched to using 4.5V flat batteries, strapped to the calculator with Scotch tape. Bulky, but much more affordable! I totally understand why later Sinclair models used 9V batteries, even though that necessitated an ugly bulge at the back of the case (which was otherwise quite elegant).

http://www.vintagecalculators.com/html/s...tific.html
http://www.vintagecalculators.com/html/c...mable.html