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.

1 to 20 MHz Colpitts Oscillator (CB6506E)
Found on Popular Electronics from the 1990s, this oscillator uses a general purpose transistor. The...
1A voltage follower (CB21073E)
This circuit was obtained from National Semiconductor documentation from the 1990s. The circuit has a...
H Bridge Current Monitor (CB5393E)
We found this circuit in a 2005 Linear Technology manual. Observe the component values and...