This circuit is from old documentation, but it can be implemented with more modern equivalent components. The transistor can be the TIP31 with a heatsink and the 1N4002 diodes.
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...