Low battery indicator (CB9133E)

This circuit was found in Maxim's documentation from the 80's. The integrated circuit is from that time, uncommon today.

Ultrasonic Receiver (CB18477E)
This is the receiver for the CB18476E, but it can be used with other transmitters found on the...
CMOS PLL Siren (CB9205E)
This circuit was found in Radio Electronics from the 90s. The CMOS integrated circuit is a PLL not...
Symmetrical Powered Amplifier (CB5024E)
This circuit was found in a 1990 Electronics World magazine. The circuit can be mounted today by...