Vintage:  Late 1990s


Circuit Designer:  Ned Ely


Designer’s Comments:   I do remember the thrills of a CK722 amplified crystal set. I played with them in the '56 to '60 period (12  years of age to 16) and then the hormones took over, and then college, jobs, wife, kids, house................
In '94 I dug out a box that had survived time and weather (the possums also nested in it at some point) that contained all of my electronic stuff from that period, INCLUDING BLUE CASED CK722's!!!!!!!! All of mine had shortened leads, but what the heck. When  the $3.00 blue leds hit the surplus market I built a "2 blue led, 2 blue CK722" flasher.  It looks COOL.  Reminds me of that saying: Something Old, something New, something Borrowed and something Blue!”



Top View of BLINKIE

There are two blue CK722s on the left and two blue LEDs on the right – the top LED is glowing!




Ned’s BLINKIE combines some of most interesting aspects of hobbyist electronics from the past 50 years.  When the battery is connected, the two LEDs will alternately flash with a bright blue color.  With the component values listed, the “flash rate” is approximately once a second.  In basic operation, this circuit is known as a bi-stable multivibrator, and is similar to circuitry used in many of today’s computers.  For example, with high precision components, it is possible to adapt this circuit to provide a fairly accurate time standard or clock.  Other variations of the circuit (known as a flip-flop) have been used as the basic counting/timing functions in most digital computers over the past five decades.  


The original BLINKIE was constructed on a 3 ˝” by 1 3/8” rectangular piece of blue Vector board.  There are only ten components (in addition to the battery, wiring and transistor sockets), so construction should be fairly straightforward – Ned did a fine, neat wiring and soldering job (see page 2 for details) and since direct soldering is required, it is strongly recommended that the two CK722 transistors be mounted in sockets to avoid any potential heat damage to these wonderful, and increasingly scarce historic devices.  


BLINKIE, Go To Page 2


50 YEARS of the CK722

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

COPYRIGHT © 2003 by Jack Ward.  All Rights Reserved.