This is IC 7805 adjustable voltage regulator circuit, can adjust voltage output: 5V up to 30V as need 6V,7.5V,8V,9V,10V and 12V etc at 1A it small and cheap[...]
It is a great idea. but It is suitable for an old hand!
If you want to a LM338 variable dc voltage power supply circuit during 1.2V to 30Vdc and can provide a current maximum to 5A.
it is protected the current over the limit that we define at about 100 mA.
The top cheap 7805 Dual Variable Regulator Power Supply. It can adjust the dc voltage with +5V to +25V and -5V to -25V at current 1 amp, using LM7805 and LM7905.
It is easy circuit but high current output.