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Old 19th January 2010, 04:55 AM   #1
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Default Invention of the Photoresistor and phototransistor

OK, I got a good question for the electronics people here. I'm talking the old guys (and I mean that with no disrespect, as I appreciate everything that is old): What year was the photoresistor invented
Also, what year did the phototransistor come out? And by this I mean commercially available. My guess on photoransistors is 1965.. But that's just a guess...

I would have posted this question in the electronics forum but it seems it has vanished..

Thank you!
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Old 19th January 2010, 05:35 AM   #2
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ALL the old germanium transistors were light sensitive.

I used OC 44s and '45s as phototransistors by scraping the black paint off.
Some were filled with an opaque material (just repainted the black), some were filled with clear translucent stuff which were the ones to use.

Mullard did produce a phototransistor at the time.
I believe it was a 44/45 with no paint and clear filling but cost a shedload more!


Andy


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Old 19th January 2010, 04:06 PM   #3
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Phototransistor, Photo transistor :: Radio-Electronics.Com

Light Dependent Resistor or Photo Resistor :: Radio-Electronics.Com
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Old 19th January 2010, 04:53 PM   #4
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Quote:
Originally Posted by gain-wire View Post
OK, I got a good question for the electronics people here. I'm talking the old guys (and I mean that with no disrespect, as I appreciate everything that is old): What year was the photoresistor invented
Also, what year did the phototransistor come out? And by this I mean commercially available. My guess on photoransistors is 1965.. But that's just a guess...

I would have posted this question in the electronics forum but it seems it has vanished..

Thank you!
I have some FPT-100's datecoded 1968 and they were cheap already then.
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Old 19th January 2010, 06:05 PM   #5
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Some golden oldies here
I remember the OCP71, the photo version of the OC71 and the ORP12 ? cadmium sulphide photo resistor.
Back to OC transistors, wasn't that a possible cause of hum, if the black coating was damaged and you had fluorescent lights etc.
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Old 19th January 2010, 08:38 PM   #6
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Yes. Airfix black paint for models was the trick for repairs.



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Old 19th January 2010, 09:58 PM   #7
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Some golden oldies here
I remember the OCP71, the photo version of the OC71 and the ORP12 ? cadmium sulphide photo resistor.
.
thanks for the picture. Which ones are photodevices?
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Old 20th January 2010, 06:52 AM   #8
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Originally Posted by gain-wire View Post
thanks for the picture. Which ones are photodevices?
Only the black OC71 would work as photo device if you rubbed the paint off
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Old 21st January 2010, 01:25 AM   #9
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Ah, OK. well I was looking more for original devices, semiconductors that were designed with the window there. I'd like to get some part numbers like the FPT-100, (thank you scott wurcer) and possibly obtain some if anyone has any...

thank you all
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Old 21st January 2010, 01:26 AM   #10
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Originally Posted by gain-wire View Post
Ah, OK. well I was looking more for original devices, semiconductors that were designed with the window there. I'd like to get some part numbers like the FPT-100, (thank you scott wurcer) and possibly obtain some if anyone has any...

thank you all
No problem, just PM me and I can send a couple.
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