old transistors photo

[Grant Richter]

The first project I ever built that "worked" was the "Piggyback" amplifier
from ? This was a 2 transistor amplifier using CK722s, I was 10 years old,
so that would have been 1966. The only headphones I had were leather ones
from a B-29 that my uncle brought back from the war.

The cool thing about the Piggyback was all the input front ends they gave
you. A coil to listen to magnetic fields, a crystal detector for AM radio, a
dynamic microphone and even instructions for gluing a little rod to a
crystal earphone diaphragm to make an electronic stethoscope.

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>
> Hi Toby:
>
> The two  rectangular black transistors with the clear plastic base in the
> upper right corner of the photo appear to be the Raytheon CK722.  That was
> the first transistor intended for the hobbyist market, and was popular in
> the early '50s.  A detailed history of this device is available at:
>
> http://www.geocities.com/ResearchTriangle/Campus/4724/index.html
>
> BTW, I sold a CK722 on Ebay for $40.00 last year, a good example of a
> "collectible" type item.
>
> Terry Michaels
>