I recently came across this schematic which would be useful for my Lab Bench Power Supply project.
Only problem is that the sink current capability of that schematic is very low (as they state at the end). Is there any way to improve that? I was thinking of adding a transistor to the output but I dont know if it would work or how to connect it.
Any help is appreciated!
Only problem is that the sink current capability of that schematic is very low
So how much current do you need?
This is crucial to being able to suggest a design.
Basically with this sort of circuit it is the size of the capacitors that cause the limitation, but it is not just a case of making them bigger. You have to drive these capacitors to transfer the charge and that is where a transistor comes in. And then their has to be time to allow the capacitors to charge and that is where the switching frequency can limit you.
For large currents you need an "isolated" DC / DC converter, and those are not easy to build or cheap to buy.
Why would large currents need it to be isolated? Did you mean "synchronous" instead?
An isolated 5V-5V converter can be wired with the positive output at ground and the negative output below ground potential. Negative 5V. It's an easy way to make a +/-5V supply, such as for opamps or other analog circuitry.
Alternatively the same 5V-5V converter can be wired to give 10V. It's a building block with multiple uses.
I would recommend using a switching DC-DC converter to generate the negative voltage. Assembled units are available cheaply on ebay and other similar sources.
Switched capacitor voltage converters are very limited in their current handling capacity compared to proper DC-DC converters. On the ones like you linked to (there are somewhat fancier ones wrapped up in a chip that you just connect caps to, and which have a regulator built in), the voltage regulation is also terrible (read: non-existent) unless you generate a larger negative voltage than you need and then regulate it down somehow.
Here's an example of a DC-DC converter to generate negative voltages that I found within under a minute of searching ebay (obv, I haven't tested these specific ones):
http://www.ebay.com/itm/500mA-3-3V-5V-6V-9V-12V-15V-Negative-Voltage-DC-DC-Converter-Boost-Buck-/272760327599
That would probably be a much better choice.