CK722 Germanium Transistor Construction Project Blinkie Page 3

BLUE BLINKIE

BLUE CK722s AND FLASHING BLUE LEDs

SUMMARY COMMENTS FROM NED ELY

“It came back to me in 1967 when my folks moved. I never could bear to throw it away, so it moved with me many times until 1994 when I saw a Popular Electronics article entitled "How To Build a One Tube Radio" by Larry Lisle. The seed was planted, the box found and dusted off and the possums were evicted. About 3 years ago I bought some blue leds for tinkering purposes and hit on the idea of using them with my 2 surviving blue CK722's in a relaxation oscillator/flasher circuit. Imagine my delight when the leds flashed! I piddled with the electrolytic values a bit to separate the flashes; the CK722's are so leaky (by nature) that the leds never fully extinguish between flashes so a lot of separation is needed. The CK722's and sockets are of 1957 vintage, the electrolytic capacitors are from the 60's, the perfboard and resistors are from the 70s and the blue leds are from the late 90s. I recently read that light flashers are always popular with novice electronic experimenters. They're fun for geezers, too!”

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Editor’s Note: There you have it. Ned’s BLINKIE is a straightforward, interesting project that you can probably build with spare parts, accumulated over the decades, from the junk box. Once completed, you’ll have a visually interesting “piece of art and technology” which can be the platform for proudly displaying your historic and ever useful CK722 transistors.

50 YEARS of the CK722

A New Volume of Projects Using the Most Famous Transistor Ever Made