We found this mixer in an American documentation. Operational amplifier supports equivalent and changed number of inputs. Power can be between 6 and 12 V.
We found this circuit in an American documentation from the 90s. Through an LED it indicates the...
Found in an EEE this circuit uses FETs of the time and a bipolar one. Current equivalent...
Both the operational amplifier and the diodes admit equivalents in this circuit suggested by...