This General Electric circuit produces pulses of light only when light stops shining on the sensor. Equivalent SCRs can be used and the trigger adjustment is done in a trimpot. The maximum load is 40W.
This simple metal detector was found in a 1960 Sylvania transistor manual. The phone must be high...
This is one of the many versions of this type of indicator that the reader can find on our...
Found in an English publication from the 1980s, this circuit can be built with equivalent...