I'm really new to electronics, and I'm wondering if adding a capacitor increases the output current. I have the following questions:

  1. Say for example, I have a 5V 1.0A Source, does the output current capacity increases if there's capacitor in parallel?

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  1. Say for example, I have a 5V 1.0A Source, and 2 x 3300uF Capacitors in parallel, and the output is drawing 5V 3.0A, can it accommodate the 3.0A requirement of the output?

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  • \$\begingroup\$ The answer to both questions is: No. What makes you think that it would? \$\endgroup\$
    – Dampmaskin
    Aug 24 '18 at 14:12
  • \$\begingroup\$ Not even sure why. Lol \$\endgroup\$ Aug 24 '18 at 14:13
  • 3
    \$\begingroup\$ Depends on which timeframe you are looking at it. Only short bursts of 3A or all the time? \$\endgroup\$
    – Arsenal
    Aug 24 '18 at 14:13
  • \$\begingroup\$ Constant 3A. Is it possible to achieve that? \$\endgroup\$ Aug 24 '18 at 14:15
  • \$\begingroup\$ @CongTibshrani no, in that case the answer provided by Elliot Alderson is correct. You can't use more power than the input is providing in the long run. A capacitor might help for short bursts but not in the long run. \$\endgroup\$
    – Arsenal
    Aug 24 '18 at 14:17

Say for example, I have a 5 V 1.0 A Source, and 2 x 3300 uF capacitors in parallel, and the output is drawing 5 V, 3.0 A, can it accommodate the 3.0 A requirement of the output?

Yes, for a very short time but otherwise no.

A capacitor in this configuration behaves a bit like the water tank in your toilet. It stores charge and can deliver a short high volume flush but has to be recharged at the rate the supply can manage and this takes some time. Flushing again to soon doesn't work as the tank hasn't refilled. Adding more capacity to your tank (parallel capacitors) increases the volume you can discharge in one flush but the refill time increases proportionally. In your case the maximum fill rate is determined by the current limit in your PSU.

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Figure 1. A smoothing capacitor smooths out the pulses from a rectified AC supply. Source: WikiMedia.

Usually we use capacitors in the configuration you've shown to smooth out a rectified AC supply as shown in Figure 1. The graph shows that the capacitor gets charged on each half-cycle and keeps the voltage up during the dips between pulses.

For more on this see Electronics Tutorials Full-wave rectifier


No, adding capacitors does not increase the current if you have a dc supply and the load is constant. However, you may increase the transient current when the load is first connected or if the load current changes suddenly.

You really need to tell us about the load and what you are trying to accomplish.

  • \$\begingroup\$ I'm trying to increase the ampere of the source. Say, a device is drawing 5V 3.0A from 5V 1.0A. Is that possible? \$\endgroup\$ Aug 24 '18 at 14:17
  • 1
    \$\begingroup\$ No, there is no free lunch. \$\endgroup\$
    – Andy aka
    Aug 24 '18 at 14:20
  • \$\begingroup\$ (in other words from what Andy said, no magic and no breaking the laws of physics) \$\endgroup\$
    – user103380
    Aug 24 '18 at 14:29
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    \$\begingroup\$ @CongTibshrani Your 5 V 3 A device requires 15 Watts, your 5 V 1 A power supply is only providing 5 Watts. \$\endgroup\$
    – Colin
    Aug 24 '18 at 14:34
  • \$\begingroup\$ A circuit could convert the 5V 1A into 3A at 1.66V or so. But a supply that's actually supplying 5V at 3A is putting out 15W of power -- it needs to get at least 15W of power coming in to do that continuously. \$\endgroup\$ Aug 24 '18 at 17:40

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