This circuit was obtained in a French documentation from 1981 and can be easily assembled. The analog instrument itself can be replaced by the current scale of an ordinary multimeter.
Taiyo Yudem SAW filters can be ordered from Mouser Electronics for UMST (W-DMA), GSM, CDMA, LTE,...
This simple circuit consists of an oscillator that can be activated both by the action of NO and...
This circuit was found in a Radio Electronics Constructor, English magazine from April 1976; The...