Found in a 1990s US publication, this alarm circuit detects when a light beam is interrupted. Optical resources may be used for the sensor and instead of the alarm a relay may be used.
Found in a 1969’s Electronic Design, this circuit operates in a narrow range of voltages....
This power stage with two counterphase transistors and coupling transformers was shown in Radio...
Found in old documentation, this circuit uses special discharge lamps (neon) of the time. The...