Electronics > Beginners

Can you increase the current of a negative voltage?

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Dan123456:
Hey all  :)

I have recently become quite intrigued with negative voltages and have been playing around with different ways of creating them  :)

One way I have been doing this is with a charge pump. The issue with this route is that they don’t produce much current.

I am wondering, is it possible to somehow increase the current with an higher current positive input?

I am probably doing a terrible job of explaining this in words so please see the diagram below  :) The exact numbers are arbitrary and am more just wondering does the “Current amplifier thingy” exist?

If feel like the answer is going to be really obvious and either going to be “of course you can you idiot, just use an op amp / whatever” or “No you dingus! That would go against the laws of physics because X” but I can’t work out which one it is  :P

Sorry, this is probably a really dumb question! Negative DC voltages are really quite new to me so I am probably missing the basics (even with stuff like when to use negative numbers into the data sheet formulas is tripping me up at this point  :P)  :P

Thanks in advance  :)

Kim Christensen:
For higher currents, it's better to use an inductor based DC-DC converter instead of a capacitive charge pump.

EDIT: Check out this simple circuit that you can experiment with. You can also get dedicated chips for this sort of thing.

Dan123456:

--- Quote from: Kim Christensen on December 10, 2023, 05:00:00 am ---For higher currents, it's better to use an inductor based DC-DC converter instead of a capacitive charge pump.

EDIT: Check out this simple circuit that you can experiment with. You can also get dedicated chips for this sort of thing.

--- End quote ---

Indeed! Thank you so much  :)

One of the other ways I have been creating negative voltages is with a LM2596 and that provides significantly more current  :)

I should have said in my original post that I realise this probably wouldn’t be the best way to go about things! I am more just hoping to understand if this is theoretically possible, even if not practical, just to further my understanding  :)

IanB:
If you are starting with batteries as in your picture, you could create a split supply from the batteries themselves. For example, using two 9 V batteries will give you a split +9 V/0/−9 V supply with balanced voltages and current. Or, if using AA cells, you could just use a few more of them to get the negative rail, e.g. use 6 cells to get +4.5 V and −4.5 V.

Andy Chee:
Another simple technique to generate +ve and -ve rails referenced to ground, is with an AC adapter with, say, 12VAC output and build a full wave voltage doubler:

The trick with this circuit is to use the centre connection point between the capacitors as the GND point, thus creating +ve and -ve rails!