I did the same (a VERY long time ago...) with the OC71. Schoolboy funds could not reach OCP71 levels. They made good phototransistors until Mullard found out and started filling the glass encapsulations with a white compound. Spoilsports :-) But all you had to do was break the glass and scrape off the compound - worked fine. I can't quite envisage doing that with a modern equivalent!
73 Paul Reeves G8GJA -----Original Message----- From: Jean-Louis Oneto [mailto:[email protected]] Sent: 20 April 2010 19:31 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] And you thought you were old I used their low power variant (OC45) to make my first audio optical link (free air, analog f course !) using flashtorch parabola as Tx and Rx "antennae". The OC45 was black painted transluscend plastic. You just had to scratch the paint to get a nice phototransitor... ----- Original Message ----- From: "Horst Schmidt" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Tuesday, April 20, 2010 2:52 PM Subject: Re: [time-nuts] And you thought you were old >I still have an original booklet from raytheon : how to build a 1 >transistor radio with a CK722. > > However, my very first transistor first transistor was an OC70 from Valvo > (German Philips). I bought it about 1956 ,I was 13 years old then in > Stuttgart Germany. > > It cost me 10.20 German Marks. A substancial sum then. I soldered the > transistor in to a socket , so the leads would not break off. > I build many different projects with it then. > > Now when I see one of the old black Philips glass encapulated > transistors, I get quite nostalgic. > But this days one hardly looks at a modern transisitor anymore. > > > > > On 21/04/2010 12:19 AM, Mike Feher wrote: >> In fact, one of the first CK-722s that I took apart did have a smaller >> hearing aid type transistor inside. Later CK-722s were of course built as >> CK-722s and even later they were in black but somewhat clear epoxy >> cases. - >> 73 - Mike >> >> Mike B. Feher, N4FS >> 89 Arnold Blvd. >> Howell, NJ, 07731 >> 732-886-5960 >> >> >> >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On >> Behalf Of J. Forster >> Sent: Tuesday, April 20, 2010 9:57 AM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] And you thought you were old >> >> Do you know the story of the CK722? >> >> In the 1950s, Raytheon was making tiny transistors for hearing aids to >> replace the pre-WW II subminiature tubes. >> >> Aside: Those tubes, developed by Norm Krim, were ruggedized and used in >> the WW II Proximity Fuzes, one of THE big inventions of WW II. >> >> Anyway, Raytheon was making piles of these tiny transistors, but many >> were >> not making hearing aid specs. Norm got the idea of packaging them to sell >> to hams to learn about transistors. If you open up one of the blue ones, >> there is another tiny case inside which is the real transistor. >> >> BTW, Norm is still alive and well in his 90s. >> >> -John >> >> =============== >> > Anyone remember the CK722 transistor? As I remember they were about $7.50, >>> a >>> considerable sum. >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >>> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> __________ Information from ESET NOD32 Antivirus, version of virus >> signature database 5044 (20100420) __________ >> >> The message was checked by ESET NOD32 Antivirus. >> >> http://www.eset.com >> >> >> >> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. This email, including any attachment, is a confidential communication intended solely for the use of the individual or entity to whom it is addressed. It contains information which is private and may be proprietary or covered by legal professional privilege. If you have received this email in error, please notify the sender upon receipt, and immediately delete it from your system. Anything contained in this email that is not connected with the businesses of this company is neither endorsed by nor is the liability of this company. Whilst we have taken reasonable precautions to ensure that any attachment to this email has been swept for viruses, we cannot accept liability for any damage sustained as a result of software viruses, and would advise that you carry out your own virus checks before opening any attachment. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
