Sure, it is ancient. You can stock a bunch of more modern voltage regulators or you can just stock one that does positive or negative, low current or high current with just adding a cheap power transistor. Nonetheless the LM723 has some great lessons on how voltage regulators work. Operating voltage goes up to about 37 V. Not a bad deal for about $0.50 US. Old, yes,, but still very educational and useful.
The LM723 has two basic sections. It has a voltage reference section and a regulator section. The reference section puts out about 7 Volts. Absolute Maximum Rating on the spec sheet says 15 mA, maximum to be drawn. From 1 mA to 15 mA this output probably won't waver even 1 mV. The voltage regulator section can tolerate about 150 mA being pulled from it. Adding an external transistor adds to this. Most any transistor will do.
For operation below 7 Volts a voltage divider is added to the output of the voltage reference. The Voltage regulator section compares this voltage to the output voltage. For operation above 7 Volts you put the voltage divider on the output and compare the 7 V reference against a tap at 7 Volts on the divider.
The LM723 has two basic sections. It has a voltage reference section and a regulator section. The reference section puts out about 7 Volts. Absolute Maximum Rating on the spec sheet says 15 mA, maximum to be drawn. From 1 mA to 15 mA this output probably won't waver even 1 mV. The voltage regulator section can tolerate about 150 mA being pulled from it. Adding an external transistor adds to this. Most any transistor will do.
For operation below 7 Volts a voltage divider is added to the output of the voltage reference. The Voltage regulator section compares this voltage to the output voltage. For operation above 7 Volts you put the voltage divider on the output and compare the 7 V reference against a tap at 7 Volts on the divider.