This wired intercom circuit was found in an English publication from the 80's. The integrated circuit can be replaced by an equivalent, just like the transistor which is a general-purpose type.
We found this circuit in the 1974 Ferranti transistor manual. The transistors are general purpose, and...
The RC network of this circuit determines the operating frequency. The emitter-coupled circuit was found...
This circuit can be used as a receiver for the CIR10534 transmitter or others described in this...