Suggested by Mullard in a1969 documentation, this circuit generates the erasure signal for tape recorders of the time. Transistors can be modern equivalents like BD136 and BD136.
This oscillator version is from an RCA documentation from the 1970s. Transistors support modern...
High selectivity filters can be obtained by combining same frequency crystals in series as shown...
This circuit was published in an article in Radio Electronics magazine in October 1988. It uses...