The star on the HP-15C's display screen

[gastopaul]

Hi,

Please, does anyone know what the star on the HP-15C's display screen means? (see the attachement)

Thanks.

[Didier Lachieze]

It's the Low Battery indicator. It's time to replace the batteries in your 15C and you'll be good for the next 15 years !

[kusmi]

(09-25-2015 12:26 PM)Didier Lachieze Wrote:  It's the Low Battery indicator.

It's really puzzling - why didn't HP just use a battery symbol to make it more clear :-)

I would have understood to just make a "dot" if there are problems manufacturing a complicated shape - but the star is equally complex than a battery symbol...

[Bill (Smithville NJ)]

(09-25-2015 03:44 PM)kusmi Wrote:  

(09-25-2015 12:26 PM)Didier Lachieze Wrote:  It's the Low Battery indicator.

It's really puzzling - why didn't HP just use a battery symbol to make it more clear :-)

I would have understood to just make a "dot" if there are problems manufacturing a complicated shape - but the star is equally complex than a battery symbol...

Since the line is a "character" line, I would guess using the asterisk Character was easier to do than trying to create a special symbol.

Of course the real manufacturing defect was creating a calculator that can run for 15 years before requiring a battery change. That means the user will only see this symbol very few times so the user easily forgets what the symbol means. Now if they had just put in a battery drain circuit so that the symbol would appear more often (such as every few weeks or month) then every user would learn what this symbol means. And the battery manufacturers would have been happier selling many more batteries. It obviously was just poor design to allow for such long operation on one set of batteries.

Bill (Tongue firmly placed in cheek)
Smithville, NJ

[Dwight Sturrock]

(09-25-2015 12:26 PM)Didier Lachieze Wrote:  It's the Low Battery indicator. It's time to replace the batteries in your 15C and you'll be good for the next 15 years !

Unless you calculate 600 digits of pi or some such long winded program.

I never noticed the long life on my 15C because I was always stealing the batteries to use in my 42S (s).

[Dave Frederickson]

(09-25-2015 03:44 PM)kusmi Wrote:  It's really puzzling - why didn't HP just use a battery symbol to make it more clear :-)

What did a battery symbol look like in 1981?

[Dwight Sturrock]

(09-25-2015 07:48 PM)Dave Frederickson Wrote:  

(09-25-2015 03:44 PM)kusmi Wrote:  It's really puzzling - why didn't HP just use a battery symbol to make it more clear :-)

What did a battery symbol look like in 1981?

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[Dwight Sturrock]

(09-25-2015 07:48 PM)Dave Frederickson Wrote:  

(09-25-2015 03:44 PM)kusmi Wrote:  It's really puzzling - why didn't HP just use a battery symbol to make it more clear :-)

What did a battery symbol look like in 1981?

4.5 volts:

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[Dave Frederickson]

(09-25-2015 08:42 PM)Dwight Sturrock Wrote:  

(09-25-2015 07:48 PM)Dave Frederickson Wrote:  What did a battery symbol look like in 1981?

4.5 volts:

-| ו | ו | ו-

Well there's your answer! So financial planners who bought a 12C in '81 wouldn't need a degree in electrical engineering to know when their battery got low.

Dave

Edit: And 2196 volts would look like ...

[Bill (Smithville NJ)]

(09-25-2015 09:09 PM)Dave Frederickson Wrote:  Edit: And 2196 volts would look like ...

Dave,

Thanks for posting this. Now I know what to do with all my old batteries.

Reminds me of when I was in grade school, I took a large transformer from an old TV and then made a half wave rectifier circuit to have DC volts. I then used it to recharge my 9 volt battery for use in my transistor radio. I found that 9 seconds would put a charge into the battery which would need to cool off before touching it. Ten seconds would cause the metal battery case to explode off the battery. The result was a battery case embedded into the plaster wall. A lot of fun and fond memories. Especially since I never succeeded in electrocuting myself - only in giving myself a lot of very strong shocks.

Bill
Smithville, NJ

[Dave Frederickson]

(09-25-2015 09:52 PM)Bill (Smithville NJ) Wrote:  

(09-25-2015 09:09 PM)Dave Frederickson Wrote:  Edit: And 2196 volts would look like ...

Dave,

Thanks for posting this. Now I know what to do with all my old batteries.

Reminds me of when I was in grade school, I took a large transformer from an old TV and then made a half wave rectifier circuit to have DC volts. I then used it to recharge my 9 volt battery for use in my transistor radio. I found that 9 seconds would put a charge into the battery which would need to cool off before touching it. Ten seconds would cause the metal battery case to explode off the battery. The result was a battery case embedded into the plaster wall. A lot of fun and fond memories. Especially since I never succeeded in electrocuting myself - only in giving myself a lot of very strong shocks.

Bill
Smithville, NJ

It's from one of Dave Britten's old threads: What to do with a bunch of slightly depleted 9V batteries? kusmi posted it!

Ahh, yes, there were lots of popped circuit breakers at home when I was growing up. I had lots of fun teaching my son how to create a carbon arc with two #2 pencils and a suicide cord!

Dave

[Dave Shaffer]

Try loading your water pistol with salt water and then squirting into a 120 VAC socket! Makes a wonderful arc until the circuit breaker blows. Tried only in the bathroom of the men's dorm when I was in college (many(!) years ago).

Or, 6 V grain-of-rice bulbs glow real brightly - for a few seconds! - at 25-50 volts. This has been experimentally verified (as any good scientist, or batch of summer students, would do).

I'm guessing most of us here tried stuff like this at some time or another.

[Bill (Smithville NJ)]

(09-28-2015 02:56 PM)Dave Shaffer Wrote:  Try loading your water pistol with salt water and then squirting into a 120 VAC socket! Makes a wonderful arc until the circuit breaker blows. Tried only in the bathroom of the men's dorm when I was in college (many(!) years ago).

I'm guessing most of us here tried stuff like this at some time or another.

In grade school, I wanted to listen to the World Series Baseball Game during class. I used a small crystal radio that required an antenna to work properly. I had already done this at home, so thought no problem doing it in class. I sat in the back of the room next to an electrical outlet. If the antenna clip was attached to the ground side of a two wire outlet, it worked as a wonderful antenna. Unfortunately, I connected to the hot side of the outlet, which grounded out through the clip to the metal outlet cover plate. What a beautiful spark and pop. The clip melted and then disconnected. I don't know if it tripped fuse/breaker or not. Fortunately, the teacher never noticed anything amiss.

The fun days of learning how stuff worked (and don't work) just by trying it.

Bill
Smithville, NJ

[Bill (Smithville NJ)]

(09-25-2015 10:13 PM)Dave Frederickson Wrote:  Ahh, yes, there were lots of popped circuit breakers at home when I was growing up. I had lots of fun teaching my son how to create a carbon arc with two #2 pencils and a suicide cord!

Dave

You had circuit breakers? We had the round screw-in fuses, which dad had long ago either put a penny behind them or a piece of foil to by bass the fuse.

I never had any problems blowing fuses and luckily we never had a house fire.
But I'm sure there were some close calls that I wasn't aware of.

Bill
Smithville, NJ

[Katie Wasserman]

(09-28-2015 02:56 PM)Dave Shaffer Wrote:  I'm guessing most of us here tried stuff like this at some time or another.

I put a bobby pin into the AC outlet and was pinned into the corner of our kitchen by a shower a sparks as the bobby pin slowly vaporized (the screw-in fuse never blew or course). My parents put in a safety (spring-loaded cover) outlet after that incident. Weirdly, they only changed that one outlet, I guess that they figured I learned my lesson.

Getting back on topic.....

HP's choice to use a '*' as the low battery indicator on the Voyagers was a mistake. I can't tell you how many times people at my client's offices have asked me what this means on their HP-12C, over the years. They should have had a 'BATT' indicator, they've got enough room for that I think.

[Dave Frederickson]

(09-28-2015 04:11 PM)Katie Wasserman Wrote:  Getting back on topic.....

We do have a tendency to get distracted or hiijacked.

Recall the episodes of Star Trek where Spock used an E6B to save the Enterprise from certain destruction? Why didn't we see an HP in ST:TNG?

Dave

[Siegfried]

(09-28-2015 07:59 PM)Dave Frederickson Wrote:  Recall the episodes of Star Trek where Spock used an E6B to save the Enterprise from certain destruction? Why didn't we see an HP in ST:TNG?

Because HP never produced a specialty electronic flight computer, just aviation program pacs

Thanks for the link which sent me on a 20' nostalgia tour of circular flight calculators.