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.

Nanoammeter (CB12009E)
This circuit allows the measurement of very weak currents indicated on an analog instrument or...
Preamplifier with tone control (CB9517E)
Found in National Semionductor documentation this circuit combines a tone control with an...
RF Generator (CB7424E)
Found in a 73 magazine from the 1980s, this circuit generates signals from 3.2 to 22 MHz. FETs can be...