Ebay DC-DC addon for soviet time power supply

I had old useless soviet time power supply 12V 3A. Added 15$ digital DC-DC converter directly after transformer + printed box. Now it work as a universal power supply 0-24V @3A, with digitally adjustable voltage and current.

This step-down was used http://www.ebay.com/itm/LM2596S-DC-DC-Step-Down-LED-Digital-Display-6V-40V-to-0-36V-for-Arduino-FR-/371085093707