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Author Topic: How do you make an Acid Photovoltaic Cell?  (Read 893 times)
RJBowman
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« on: April 05, 2016, 04:00:13 am »

This is from memory from circa 1980. I was twelve, and my local library had a pre-first-world-war book of electrical experiments. Most of the devices I recall from the book I can fond documented on the web, but one remaining enigma is the photovoltaic cell.

This is not like modern solar cells made of silicone and semiconductors. The photovoltaic cell of the early 20th century was an acid battery made from metal plates in a glass jar of chemicals. I don't know what the liquid in the jar was (acid is my assumption based on what I know of old wet batteries) and I don't know what the plates were but I suspect that one of them was probably a strip of silver.

I don't think that it was a true solar battery; I think that the electrodes are probably consumed by the acid to produce energy just as happens in a regular chemical cell, but the unique feature of this battery is that it only works when light shines on it.

The experiment book described a use for the cell: the small current that it produces can be used to trip an electromagnetic relay to switch off electric lights when the sun comes up. That's a fairly impressive feat of automation for that era.

So I am asking of anyone can provide any more information? What kind of metal were the electrode plates made from? What was the chemical solution in the jar? Do the electrodes require any kind of treatment to make them photosensitive?

I would be grateful for any information that anyone can provide.
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sgt_bear
Swab

Switzerland Switzerland


« Reply #1 on: May 22, 2016, 04:12:55 pm »

Hi

I don't know if this is still relevant, but i try to answer.

I think, this is about the photoelectric effect at all. If you place a battery in a glass enclosure, and place it into sunlight, its current will be slightly higher

http://www.renewable-energy-concepts.com/solarenergy/solar-basics.html
http://www.historycommons.org/context.jsp?item=a1839photovoltaic

he photovoltaic effect (PV) occurs when the energy from photons strikes a semiconducting material such as silicon or platinum, and transfers its energy to an atom of the semiconducting material. The energized electron then escapes its bond and generates an electric current. The “gap” created by the escaped electron works with the electron to create the current.
So the electrode could be Platinum, i don't know about the acid, but don't think it will matter very much.
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RJBowman
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« Reply #2 on: May 22, 2016, 04:46:56 pm »

What i'm looking for is a little more significant; the difference was enough to trip a homemade relay.
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J. Wilhelm
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« Reply #3 on: May 22, 2016, 05:39:38 pm »

What i'm looking for is a little more significant; the difference was enough to trip a homemade relay.

Significant in what way? Current wise? Sgt. Bears's answer is correct IMHO. In this case, platinum is that alternative to silicon.
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sgt_bear
Swab

Switzerland Switzerland


« Reply #4 on: May 22, 2016, 06:38:36 pm »

What i'm looking for is a little more significant; the difference was enough to trip a homemade relay.

Do you know any of the size of the cell? Maybe the bigger the cell, the bigger the change... and depends on the relay spec's
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RJBowman
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« Reply #5 on: May 22, 2016, 06:50:01 pm »

It was a glass jar like might have been used to can vegetables; probably a quart jar. It was full of liquid; probably acid. It had electrodes made of strips of metal. One of the electrodes might have been foil.
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Peter Brassbeard
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« Reply #6 on: May 23, 2016, 03:34:24 pm »

A google search for "liquid junction solar cell" gets lots of hits, but good luck finding what you seem to be looking for among them.
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RJBowman
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« Reply #7 on: May 23, 2016, 05:02:22 pm »

A google search for "liquid junction solar cell" gets lots of hits, but good luck finding what you seem to be looking for among them.

It seems to be bringing up scientific articles, but nothing about the old fashioned device I've looking for. I guess it's more obscure and forgotten than I had thought.
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GCCC
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« Reply #8 on: May 23, 2016, 05:16:37 pm »

This may or may not be a useful suggestion, but if any of the old issues of whatever the magazine is for the Boy Scouts are online, this sounds like just the sort of thing they would have suggested for a project. If that doesn't pan out, then perhaps contacting someone over at Make would yield results.
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RJBowman
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« Reply #9 on: May 23, 2016, 06:39:35 pm »

I was thinking that if I could get to a decent sized university library I could check the Readers Guide to Periodical Literature from circa 1910. I remember the old book giving a description of a setup where a farmer used to cell to control lights around his chicken coup, which seems like a project that might have been published in Popular Mechanics are possibly a farmers' magazine.
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Peter Brassbeard
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« Reply #10 on: May 24, 2016, 06:30:23 am »

The magic search terms appear to be "Becquerel photogalvanic cell".
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RJBowman
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« Reply #11 on: May 25, 2016, 05:12:59 am »

The magic search terms appear to be "Becquerel photogalvanic cell".

Thank you for the leed. Look at this :
https://www.google.com/search?q=Becquerel+photogalvanic+cell&client=tablet-android-att-us&prmd=imsvn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi43c3NqvTMAhUSQ1IKHaACCewQ_AUIBygB&biw=1024&bih=600

The first image is a diagram of the cell. If it can be done then this hint you provided should lead to the solution  (and the electrodes suspended theren).
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