+/- 12V DC DC Converters

[German_EE]

Sorry folks but my Ebay search skills are failing me. I'm looking for some DC-DC converters that can take a nominal 20V input and output +/- 12v @ 200mA per channel. Does anybody have a favorite supplier on Ebay that might have these in stock?

[mariush]

Why not quickly make them on a prototyping board using two MC34063 ICs and basic components... it gets even cheaper if you buy 10-25 pcs of each component.

Farnell has a lot of them in stock, here's a few through hole ones easy to solder on proto boards:

1. http://de.farnell.com/texas-instruments/mc34063ap/ic-dc-dc-controller-34063-dip8/dp/1053579
2. http://de.farnell.com/texas-instruments/mc33063ape4/ic-dc-dc-converter-33063-dip8/dp/1053584

Calculator software is here (even shows you how to connect things): https://sourceforge.net/projects/mc34063uc/

Just pay attention to the inductor when you choose it .. for example you may see minimum 80 uH with Ipeak of 0.5a for 20->12v @ 0.25a and you may see minimum 105 uH with Ipeak of 0.8 , you could go with a standard 120uH for both and Ipeak of 1A or something like that... buying same inductor in bigger quantity saves money. For example http://de.farnell.com/multicomp/mcsch895-121ku/induktivit-t-120-h-10-radial-bedr/dp/1864383 would work and it's cheap in quantity.

And for weird resistors you could put two or three in parallel to get the value you want (like three 1 ohm resistors in parallel to get 0.33-0.39 ohm)

[Buriedcode]

Why not use a standard buck converter, with a coupled inductor?  1:1 inductors are plentiful on Farnell and can provide a negative rail, albeit not fully regulated.  It'll require two extra components (diode and output cap for the second rail) and its regulation tends to track the positive rail, whilst being able to provide more current than a charge pump.