The use of field effect transistors in this circuit improves its performance. This configuration is from a 1975 circuit manual. The transistor can be any general-purpose FET such as MPF102 or BF245.
The circuit presented is suggested by National Semiconductor in its Linear Applications Handbook. The...
In this application we show how to get tuning from 0 V to an LM350 regulator IC. The setting also...
This frequency corresponds to musical note C3. Frequency accuracy depends on the accuracy of the...