This variable oscillator with power step for alarms was found in an American documentation from the 90's. The power transistor must be equipped with a heat sink.
November 2016 - Texas Instruments' new TLV8802 nano-power operational amplifiers for wireless...
This sophisticated photometer that has a light comparator with LED indicator came out in an...
This is a version of the previous circuit that includes a tone modulator based on a Hartley...