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Selenium cells

Chapter 7: CHAPTER VI The Care Of Selenium Cells
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About This Book

The manual begins with a technical overview of selenium as an element and its three physical forms, then compares cell designs and the principles by which a thin metallic selenium bridge varies resistance with illumination. It gives step-by-step instructions and tooling for building Fritts-style cells, including surface preparation, hot-press application of selenium and gold contacts, assembly and sealing. Detailed procedures for testing, maturing and measuring cell performance with bridge and substitution methods are provided along with treatments to adjust sensitivity. Practical uses and maintenance guidance cover photometry, optical signalling and recording, automatic controls, telephony-related applications, and battery-like current generation.

CHAPTER VI
The Care Of Selenium Cells

A selenium cell will give much better service and have a longer life if a little care is taken with it. These suggestions if followed will prevent to a great extent irreparable damage to the cells.

Keep them cool. Do not allow them to become heated to any extent or the gold foil will combine with the selenium to form a gold selenide and destroy the sensitiveness of the cell. This condition will be indicated by dark brown splotches on the face of the cell.

Use as small current values as possible to accomplish a desired result. This demands the use of high resistance relays. Resistances may be employed in the circuit to limit the current but a high resistant relay is the proper solution.

Use the proper voltage as determined by the testing set.

Do not expose light sensitive cells to bright light for excessively long periods of time. It fatigues the cell and causes it to become insensitive temporarily.

When using generator cells do not pass a current from an outside source thru them while lighted. This destroys temporarily the generating powers of the cell.

Keep the cells dry. If not of the sealed type keep them in a box having a few lumps of calcium chloride in the bottom to absorb moisture.

When not in use they should be kept in a light tight box but should be exposed to light each day or so regardless of whether they are used or not. This aids maturing and retains the sensitiveness of the cells.

Should their resistance drop to any great extent after continued use it can again be raised by treating with an alternating or pulsating current as described under treating and testing cells.

THE END

Transcriber's Notes:


The cover image was created by the transcriber, and is in the public domain.

Antiquated spellings were not corrected.

The illustrations have been moved so that they do not break up paragraphs and so that they are next to the text they illustrate.

Typographical errors have been silently corrected