We found this circuit in the Linear Applications Handbook of the 1994 National Semiconductor. The transistor must be a high voltage type and the LM3900 power supply must be symmetrical.
We found this frequency meter circuit in a 1974 documentation. The circuit is powered by 12 V and...
This high gain small signal amplifier circuit was found in an old publication on transistors....
This circuit can be used with input voltages up to 750 V, regulating the current between 200 uA...