A friend of me wants the circuit enhances Voltage 12VDC from be 24VDC or DC to DC Converter 12V to 24V. By fix reveal that be the circuit is simple , build not difficult. I then advise this circuit try out think use just Transistors D1616 = 2 pcs. with transformer the small-sized , mix with other equipment a little only again. Follow a picture has can to use this circuit with small fan motor.

http://www.circuitpowersupply.com/circuitblog/easy-dc-converter-12v-to-24v/