TThis is the PCB of a high speed low-noise super shunt regulator board. The regulator circuitry is based on Stax's patented shunt topology( see below). The circuit prevailed in the diy circle and commercial designs( probably right after the expiration of the patent). "Mr. FET", Erno Borbely did a similar design using all FETs in early 90s. In this board we incarnated the original Stax design using readily accessible BJT transistors and allow a wide settable voltage range from +/-15VDC to +/-70VDC. Board Dimension : 128mm x 73mm Board thickness : 2mm Copper Thickness :75um( 4 times normal thickness !!) Surface finishing : Double-sided solder resist coating for maximum reliability We provide schematic and part list for this PCB by EMAIL to buyers. Specifications: Input voltage : AC 22Vx2 to 55Vx2 Output voltage : three ranges , user settable with change of two resistor values : 1. +/-15V to +/-30V 2. +/-30V to +/-50V 3. +/-50V to +/-70V We do air shipping worldwide at US$7.00.