i have a 12v power supply and fan 5v 150mA and voltage regulator L7805 cv to reduce the voltage to 5volt . i need a circuit to just turn the fan on /off by switch .

can i connect the fan directly to vo & gnd from the L7805 ?

  • \$\begingroup\$ You'll need capacitors on the 7805 and in turning about a watt ((12-5) * .150) to heat, quite probably a heatsink too. This is really not a very good idea, get a power supply and fan that match. \$\endgroup\$ – Chris Stratton Oct 11 at 14:18
  • \$\begingroup\$ should i use free wheel diode in parallel in fan . or i dont have to ? \$\endgroup\$ – Tareq Oct 11 at 14:40
  • \$\begingroup\$ Use a switching regulator, not a 7805. They make little drop-in replacement modules if you look around on your preferred distributor's on-board power supply section. \$\endgroup\$ – Hearth Oct 11 at 17:25

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