Light Sensor

[charger105]

Hi all.
I've noticed a few references to a light sensor on the old Pulsar LEDs. Can anyone explain what this is for ? Is it to vary the intensity of the display, based on ambient light conditions ?

Rgds,
Andrew.

[bruce wegmann]

You have it exactly right. It's a miniature cadmiun-sulphide photocell [a type of light-sensitive variable resistor]; easiest to see on the P3s...sitting vertically on the right-hand side of the display. Later models and Ladies watches have even smaller versions of the same part.

[gjlelec]

Bruce, when you state the resistor is variable, is that actually how it works ie constantly dimming or brightening the display or is it only capable of two settings ie dim or bright

[bruce wegmann]

Totally and continuously variable in response to ambient light level. Resistance is high in low-level light, low in high-level light; in other words, it is inversely proportional to light level. Purely a power-saving feature. A quick test of function is, in a moderately-lit room, shade the sensor with a finger. The display should get noticibly dimmer, and return to previous brightness when you move your finger away.

[Mark A.]

Hi.

Guy Ball used to have a reprint of an article that was written by Lucien Trueb and published in the April 2004 issue of Watch Time. I haven't seen this article transferred over on the site Ed is maintaining.

In that article it mentions that the output of the display on "the production models" of Pulsars was set at 100%, 50%, 25%, and 12.5%.

I'm not sure if this is correct, but it seemed like an informative article.

Regards,

Mark A.

[retroleds]

Mark A. - I'm impressed!! Someone remembered an article by it's author! I went looking for that article - no luck by word search because it is a .pdf of scan; essentially, a picture. I found the article and added it to the section I was calling "Instructions" on the menu. That area is now "Articles & Instructions", the article is about half-way down the page.
It is also here - http://www.ledwatches.net/articles/WatchTimeArticle.pdf

It must have been a link buried in a page, that is only linked to from another page.....I'm trying to get things moved to a point where they can be referenced within two clicks of the menu.

You were right about the different brightness settings being refernced in that article - good job!!

[charger105]

Thank you for your replies gentlemen. Very informative. That article was a good read. It stated that Electro-Data produced the dot matrix modules for the prototypes, and from then on segment displays were used for the mass produced model.
I have a P3 date command with a dot matrix display. Did they revert back to dot matrix displays in later years ?

Rgds,
Andrew.