This circuit is from 1980s documentation. The maximum operating frequency is 3.5 MHz. The current of the LED can be from 0 to 100 mA. The integrated circuits used are from that time.
This alarm oscillator was found in the December 1974 issue of Radio Electronics magazine. The...
This variable frequency oscillator (VFO or OFV) was obtained in an old Motorola documentation. The integrated...
This resistive sensor was found in a 1969 US documentation. The circuit uses transistors of the...