Yes, i've seen this "pump-up" circuit but i would prefer a real 24 vdc to
make sure the rele is correctly energized.
My 26 vdc - 4 ways Dow-Key coax rele works also with 12 vdc, but the problem
is : "is it affordable at this coil voltage???"
A stronger 24 vdc would be better...

Thank you,
73 de Riccardo IK5WQO