Datasheet of This battery powered intercom was found on a January 1947 Radio Craft. |The circuit is 4-way but can be modified by changing the key.
This audio circuit was found in the February 1983 issue of Radio Electronics magazine. The...
This circuit was obtained from an English magazine from 1981. The magazine no longer exists, but...
This circuit was found in a 1979 documentation. The transistors can be the BD136 and BD135,...
