Recently I have made a power supply which gives dc voltage between 1.2 ~ 30 But when I use my multimeter I can measure AC voltage too is that normal ? Shouldn't it be zero ? enter image description here enter image description here enter image description here

  • \$\begingroup\$ How much of an AC waveform do you see? What is its voltage? What is its frequency? Does it change as you draw current on the DC side? \$\endgroup\$ – Puffafish Feb 26 '16 at 12:17
  • \$\begingroup\$ Many (most, probably) multimeters are AC coupled on the AC ranges so they will read 0V if there is no ripple. If you connect the multimeter across a battery (on an AC range) what do you read? \$\endgroup\$ – Spehro Pefhany Feb 26 '16 at 12:17
  • \$\begingroup\$ @AndyHall the AC output is almost as twice as the DC and yes it changes as I change the DC voltage \$\endgroup\$ – user90575 Feb 26 '16 at 12:22
  • \$\begingroup\$ @SpehroPefhany I can get 18 ACV out off a 9 v battery so is it my multimeter \$\endgroup\$ – user90575 Feb 26 '16 at 12:56
  • \$\begingroup\$ can we say "get a new meter?" \$\endgroup\$ – Robherc KV5ROB Feb 26 '16 at 14:32

Since your multimeter reads significantly differently from non-zero with a battery input, your power supply is probably okay. That's a bit of a strange voltage reading- maybe 1/2 wave rectified with DC coupling.

You van try a capacitor in series with the input of the meter- maybe 10uF.


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