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 circuit was found in an old Electronic Design. It makes use of sidacs and operational not very...
Although it was found in a British magazine 1976, this circuit can be easily upgraded with the...
This circuit that uses only transistors that are still common was found in a 1995 documentation. The TIP41...
