For the next project, a 24V power supply is required. But no transformer is needed. The big, heavy, separate regulator (LM7824) should be added etc etc …  And the consumption is just a few mAs. Well, then be DC – DC converter! The point was that 12v should be converted to 24V. Be simple with few parts. Therefore, choose the old, proven MC34063 circuitry. Not complicated:

MC34063 Step Up converter schematic

R2 is two 1 ohms in parallel. This is not marked separately in the drawing. Here is the official MC34063 datasheet, which is worth studying.

Here is an earlier project, that we used for a while as a tube preamplifier power supply.

Finally, here is a very good calculator program.