This circuit was found in the October 1989 issue of Radio Electronics magazine. It drives an auxiliary relay with the call signal for a possible louder bell.
We found this circuit in a 1977 Radio Handbook. The lamp is the critical component, being 120MB at the...
This circuit was suggested by Philips in 1967 documentation. The circuit receives modulated light and has...
This circuit of a 1969 Electronic Design uses RTL logic. The setting can be adapted to TTL. The...