This is voltage booster schema diagram.you can get 24V from 12V DC.Q1 and Q2 are D1616.If you are unable to find D1616 You can use 2N 3055,C2236,SL 100.

Note
# For high current (around 5A) games use 2N 3055 transistor or more powerful Darlington pairs for Q1 and Q2.
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