Cheap Solar Cells and LCD

[jeffpda]

I am looking for a source for the solar cells used in cheap solar
calculators like the ones sold in dollar stores and Walmarts. I have
been searching the web and haven't found much. I stripped some
calculators and couldn't find a part number on the solar cells. I want
to power a device which uses an lcd display (.5" or larger characters)
and small PIC chip. I am also looking for the cheapest 2 line
alphanumerc lcd available (so far the cheapest I've found for quantity
of 1 thousand is about $5 US).

Thanks in advance.

 

[Ian Stirling]

I am looking for a source for the solar cells used in cheap solar
calculators like the ones sold in dollar stores and Walmarts. I have

These produce almost no power.

been searching the web and haven't found much. I stripped some
calculators and couldn't find a part number on the solar cells. I want
to power a device which uses an lcd display (.5" or larger characters)
and small PIC chip. I am also looking for the cheapest 2 line
alphanumerc lcd available (so far the cheapest I've found for quantity
of 1 thousand is about $5 US).

Certainly not enough to run on eof these.

 

[Macgyver]

I am looking for a source for the solar cells used in cheap solar
calculators like the ones sold in dollar stores and Walmarts. I have
been searching the web and haven't found much. I stripped some
calculators and couldn't find a part number on the solar cells. I want
to power a device which uses an lcd display (.5" or larger characters)
and small PIC chip. I am also looking for the cheapest 2 line
alphanumerc lcd available (so far the cheapest I've found for quantity
of 1 thousand is about $5 US).

Thanks in advance.

I was working on a similar project last year but on a much bigger scale
(if that makes sense!) for products requiring small cells and larger
flexible solar cells. After looking thru the websites of a few hundred
solar cell and panel manufacturers and distributors (oh the internet is
such a wonderful tool), I was able to narrow down the list to a few
that you may find helpful.

http://www.sinonar.com.tw/
http://members.aol.com/photontek3/photon3/itf1.html
http://www.microsolpower.com
http://www.iowathinfilm.com
http://www.siliconsolar.com
http://www.flexcell.ch
http://www.gepower.com/prod_serv/products/solar/en/solar_cells.htm

And a distributor that may be helpful
http://www.solar-world.com

I did not include the manufacturers that make the cells for those
calculators as the MOQ is in the thousands. There should be other
local distributors that stock some of these company's cells if you keep
looking.

In the end, if you only want small quantities quickly, buying very
cheap solar powered calculators may be a viable option (just make sure
that the solar calculator is not a battery-powered calculator with a
fake solar panel like the one I found!).

 

[jeffpda]

Thanks Macgyver! This is good stuff.

 

[[email protected]]

I am looking for a source for the solar cells used in cheap solar
calculators like the ones sold in dollar stores and Walmarts. I have
been searching the web and haven't found much. I stripped some
calculators and couldn't find a part number on the solar cells. I want
to power a device which uses an lcd display (.5" or larger characters)
and small PIC chip. I am also looking for the cheapest 2 line
alphanumerc lcd available (so far the cheapest I've found for quantity
of 1 thousand is about $5 US).

Thanks in advance.

Would this help?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44768

 

[jeffpda]

Thanks for the link but I am looking for just the cells themselves to
manufacture into a product. (indoor cells that operate under 200 lux)

 

[Christopher]

Hello Jeff,

I am looking for a source for the solar cells used in cheap solar
calculators like the ones sold in dollar stores and Walmarts. I have
been searching the web and haven't found much. I stripped some
calculators and couldn't find a part number on the solar cells. I want
to power a device which uses an lcd display (.5" or larger characters)
and small PIC chip. I am also looking for the cheapest 2 line
alphanumerc lcd available (so far the cheapest I've found for quantity
of 1 thousand is about $5 US).

Here is a solar cell I like, flexible thickness of a soda can with and
a few other interesting features.

http://www.bigfrogmountain.com/powerfilmsolarproducts.htm



* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com

 

[jeffpda]

These produce almost no power.

After measuring the output of these solar cells, I have to agree that
you are correct.

Certainly not enough to run on eof these.

How do they manage to run the solar calculator on a microamp budget.

 

[Spehro Pefhany]

After measuring the output of these solar cells, I have to agree that
you are correct.


How do they manage to run the solar calculator on a microamp budget.

The purpose-specific LSI chip is designed from the ground up to use
very little current. Eg. JT6A72-CS Toshiba 8-digit calculator:

1.9uA wait/3uA operating typical @1.4V (it incorporates a charge-pump
voltage doubler, so the actual current draw of most of the chip is
half of that). This particular chip blazes at a mind-bending 18kHz
when calculating and then throttles back to a more leisurely 7kHz when
waiting for a keystroke. Current draw surges to 4uA (max) peak during
the worst-case calculation (square root of all 9's) for a worst-case
time of 263.2 milliseconds.

Typically, with solar power, possible excess voltage from the solar
cell is clamped by an external shunt regulator LED.


Best regards,
Spehro Pefhany

 

[Lostgallifreyan]

The purpose-specific LSI chip is designed from the ground up to use
very little current. Eg. JT6A72-CS Toshiba 8-digit calculator:

1.9uA wait/3uA operating typical @1.4V (it incorporates a charge-pump
voltage doubler, so the actual current draw of most of the chip is
half of that). This particular chip blazes at a mind-bending 18kHz
when calculating and then throttles back to a more leisurely 7kHz when
waiting for a keystroke. Current draw surges to 4uA (max) peak during
the worst-case calculation (square root of all 9's) for a worst-case
time of 263.2 milliseconds.

Typically, with solar power, possible excess voltage from the solar
cell is clamped by an external shunt regulator LED.


Best regards,
Spehro Pefhany

I found that 69 n! on a scientific 10 digit calculator makes it chew
hardest, so if that function is available, it's fun to try. Newer ones do
it fast though, the first one I tried was a Texas Instruments one in 1982
which took around 10 seconds or more.

 

[Jim Thompson]

I'd heard that some people loved their calculators, but I had no
idea...


I think the TI-59 (the one with the magnetic card reader) was in that
general range for factorials.


Best regards,
Spehro Pefhany

Yep, I had that one.

...Jim Thompson

 

[Spehro Pefhany]

I found that 69 n! on a scientific 10 digit calculator makes it chew

I'd heard that some people loved their calculators, but I had no
idea...

hardest, so if that function is available, it's fun to try. Newer ones do
it fast though, the first one I tried was a Texas Instruments one in 1982
which took around 10 seconds or more.

I think the TI-59 (the one with the magnetic card reader) was in that
general range for factorials.


Best regards,
Spehro Pefhany

 

[[email protected]]

I'd heard that some people loved their calculators, but I had no
idea...


I think the TI-59 (the one with the magnetic card reader) was in that
general range for factorials.


Best regards,
Spehro Pefhany

Whoa! My Casio fx-115MS (dual solar/battery) calculated 69! in a split
second. 1.711E+98

70! results in a Math Error (overflow?)

Not bad for $15 at Target. (Used it for taking the PE exam - they have
a very limited selection of allowed calculators.)

Michael

 

[Spehro Pefhany]

Whoa! My Casio fx-115MS (dual solar/battery) calculated 69! in a split
second. 1.711E+98

70! results in a Math Error (overflow?)

Not bad for $15 at Target. (Used it for taking the PE exam - they have
a very limited selection of allowed calculators.)

Michael

We were talking late 70's early 80's era calculators, with LED
displays, not this newfangled stuff. The slowest calculator I've owned
is a cute little handheld Commodore LED display unit (9V battery, PET
style 'chiclet' keyboard). Tan(0.5) blanks the display for
approximately 3 seconds. Chip is a MOS MCS7529 in white ceramic and
gold package, with an ITT Led driver chip. Through-hole 0.1" pitch all
the way.


Best regards,
Spehro Pefhany

 

[Keith]

Whoa! My Casio fx-115MS (dual solar/battery) calculated 69! in a split
second. 1.711E+98

70! results in a Math Error (overflow?)

Just tried the HP11/12C emulator I have here on my laptop. It
calculates 1000! (4.024E2567) in well under a second. 1001
overflows (strange).

Not bad for $15 at Target. (Used it for taking the PE exam - they have
a very limited selection of allowed calculators.)

This one was free, but I doubt they'd let a laptop into the PE
exam.

 

[[email protected]]

Just tried the HP11/12C emulator I have here on my laptop. It
calculates 1000! (4.024E2567) in well under a second. 1001
overflows (strange).


This one was free, but I doubt they'd let a laptop into the PE
exam.

I doubt it too.

I would have liked to just bring my old TI-85 to the exam, but I guess
they didn't want me to copy down all the questions and re-sell them on
the internet. (Like I'd have time to do that...!!!)

Annoyed me too, that they don't allow digital watches (!!??) - I had to
buy a $6 "analog" watch from Wal-Mart to keep the time.

Michael

 

[Lostgallifreyan]

I'd heard that some people loved their calculators, but I had no
idea...


I think the TI-59 (the one with the magnetic card reader) was in that
general range for factorials.


Best regards,
Spehro Pefhany

When it's all you have as a kid you make the best of these things. >
I had one of those TI-59's once too, later, but I didn't make much use of
it.

Another fun thing I used to do was take a constant multiplier like
2.1452767 and start with 1 or other seed value, and when it got to the top
and overloaded, I'd press CE to let me carry on with the truncated value. I
learned that you can get a chaotic, even random output if you chose good
starting values, despite sticking to a rigid and repeatable set of rules.
That experience helped me to understand a bit of chaos theory a few decades
later, and also to make true white noise generators in FM synthesis on
Yamaha SY99 and SY77 synthesizers.

Ok, it's true, I have LOTS of time. But when I see the way coding is
getting in certain operating systems that should be nameless, and in some
electronic hardware too, though to less extent, I think plenty of time and
less money might do the whole industry a lot of good.

One thing I like best is the tiny answers to complex problems like the
'Best of EDN' circuits. It takes either a lot of inspiration, or a lot of
testing time, to come up with stuff like that.

 

[Rich Grise, Plainclothes Hippie]

When it's all you have as a kid you make the best of these things. >
I had one of those TI-59's once too, later, but I didn't make much use of
it.

Another fun thing I used to do was take a constant multiplier like
2.1452767 and start with 1 or other seed value, and when it got to the top
and overloaded, I'd press CE to let me carry on with the truncated value. I
learned that you can get a chaotic, even random output if you chose good
starting values, despite sticking to a rigid and repeatable set of rules.
That experience helped me to understand a bit of chaos theory a few decades
later, and also to make true white noise generators in FM synthesis on
Yamaha SY99 and SY77 synthesizers.

Speaking of "chaos" from simplicity, have you ever heard of "the
Mandelbrot set"? Actually, it's more merely "fractal" than "chaotic", I
think.
I found some examples here:
http://www.google.com/search?q="mandelbrot set%22

Cheers!
Rich