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.

Water Level Alarm (CB5313E)
This circuit produces a loud sound in the speaker when water level reaches the sensor. The power...
1092 LED panel indicators (COM001E)
May 2016 - It can be obtained from Mouser Electronics new display 1092 from VDC. The new LED...
Two transistor assisted ignition (CB6391E)
This Motorola circuit is from 1965. Collector currents must be 7 and 12 A for transistors....