1-25 volt power supply

[audioguru2]

The last schematic has a voltage gain of 10. But many opamps have inputs that cannot go as low as zero voltage without having a negative supply.

 

[Kevin Weddle]

This could be a better circuit.

View attachment 42110

 

[audioguru2]

This could be a better circuit.

Its voltage gain is only 1 so you cannot use an accurate 2.5V reference and produce a 25V output.
Therefore the voltage gain was made to be 10.