Getting different measurements from power supply vs a battery
A linear regulator will only give you what you feed into it, at best, in the case of the  L78L33, a volt or two less depending on the loading.  

If you want the 7.6V output shown in the schematic, then you should feed it with about 10V. 

For 3.3V output, the datasheet shows an input of at least 5.3VDC, at 0 to 40mA out. If you add the 4.3V zener you should give it about 10V.  



For your 24V rail you need to make or buy a switching DC-DC converter, for the 3.3V supply you can consider an LDO regulator of better performance dropout-voltage-wise than the ancient L78L33 (which is also pretty power-hungry for battery use).