Invention of the Photoresistor and phototransistor

gain-wire · 19th January 2010, 04:55 AM

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!

poynton · 19th January 2010, 05:35 AM

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

.

Steve Dunlap · 19th January 2010, 04:06 PM

Phototransistor, Photo transistor :: Radio-Electronics.Com

Light Dependent Resistor or Photo Resistor :: Radio-Electronics.Com

scott wurcer · 19th January 2010, 04:53 PM

Quote:

Originally Posted by gain-wire

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.

Mooly · 19th January 2010, 06:05 PM

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.

poynton · 19th January 2010, 08:38 PM

Yes. Airfix black paint for models was the trick for repairs.

.

gain-wire · 19th January 2010, 09:58 PM

Quote:

Originally Posted by Mooly

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?

Mooly · 20th January 2010, 06:52 AM

Quote:

Originally Posted by gain-wire

thanks for the picture. Which ones are photodevices?

Only the black OC71 would work as photo device if you rubbed the paint off

gain-wire · 21st January 2010, 01:25 AM

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

scott wurcer · 21st January 2010, 01:26 AM

Quote:

Originally Posted by gain-wire

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.

19th January 2010, 04:55 AM	#1
gain-wire diyAudio Member Join Date: Nov 2004 Location: NCR	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! __________________ Trans-directional-servo-logamp non-zerocrossing autogain compressing thingamajig

19th January 2010, 05:35 AM	#2
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	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 . __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

19th January 2010, 08:38 PM	#6
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	Yes. Airfix black paint for models was the trick for repairs. . __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

21st January 2010, 01:25 AM	#9
gain-wire diyAudio Member Join Date: Nov 2004 Location: NCR	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 __________________ Trans-directional-servo-logamp non-zerocrossing autogain compressing thingamajig

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19th January 2010, 04:06 PM	#3
Steve Dunlap diyAudio Member Join Date: Sep 2008 Location: Here	Phototransistor, Photo transistor :: Radio-Electronics.Com Light Dependent Resistor or Photo Resistor :: Radio-Electronics.Com

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