Published by Philips in 1965 documentation, the sensor for this circuit is a common LDR. The transistors are general-purpose types from the time, only TR3 is a power type according to the load.
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
Found in the July 1994 Electronics Now magazine, this circuit drives a relay up to 12 V depending on...
May 2017 - Mouser Electronics is delivering a voice recognition kit from NXP Semiconductors. The...