I am needing to power a 24vdc gate motor, it is rated for 24vdc 1A on battery power and 24vdc 4.5A on mains power, i have a laptop charger(AC Adapter) that does 220vac to 24vac and 4.5A but i need the output in VDC. The motor is rated for 3000lbs load and will only be moving a 120lbs load as it is re-purposed for a mixer.

my answer as far as i have searched is a bridge rectifier circuit, i want to use 4x 1N4007F diodes, but i need to know what the voltage drop will be across the circuit so that i can add the right capacitor the maintain the voltage generally in the 24vdc range... I understand it is not ideal but i do need a workable solution for the time being.

South africa does not have surplus electronic supply stores and importing is not an option at the moment.

in short i need to convert 24VAC to 24 VDC with max A of 4.5

  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$
    – clabacchio
    Jan 17, 2019 at 13:25
  • \$\begingroup\$ "i have a laptop charger(AC Adapter) that does 220vac to 24vac" Please edit your question and add a clear photo of the ratings label of that power supply (i.e. the manufacturer's label, usually stuck on the bottom of the power supply, showing the rated input & output voltages & currents). Thanks. \$\endgroup\$
    – SamGibson
    Jan 18, 2019 at 4:17

1 Answer 1


You will need a much bigger diode than a 1N4007, which is only rated at 1A. You will need at least 5A for your specification. Given that motors can draw a large surge current when starting, larger still would be better. Maybe 10A.

Try it without a capacitor. Motors will run on ripply DC. A big capacitor would boost your 24V up as high as 33V, which won't help.

Are you sure your power supply is really 24V AC? I have never seen such a thing as an AC adaptor for a laptop.

  • \$\begingroup\$ yes very sure, its ac to ac adapter with a manual switch to select between output V of 12 to 24vac \$\endgroup\$ Jan 17, 2019 at 19:17

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