We found this circuit in the National Semiconductor's Linear Applications Handbook of 1994. The circuit uses an operational transconductance amplifier.
Settings like this can be found at various points on this site. The trigger door can be a 4093...
Toshiba LDO Regulators Toshiba has a wide variety of low voltage drop (LDO) linear regulators...
With a 10 V input this circuit provides a 25 V output. The circuit is from December 1985 Radio...