das psu des nac liefer keine -5 
du kannst einen (gleich)spannungswandler verwenden um z.b. aus den +5v/+12v die für mk pcb benötigten -5v zu gewinnen. das negatron ist oft zitierte paradebeispiel für diese aufgabe. ich hatte mitr mal ein paar alternative bauteile rausgesucht aber gerade finde die bookmarks nicht die elektrocracks hier an board haben sicher nen tipp welche bauteile sich eignen. alternative kannst du auch zweites (stecker)netzteil für die +5v verwenden 
ZitatAlles anzeigenNegatron is a buck-boost converter that takes a positive voltage and turns it into a negative voltage that you can use with amplifier circuits and more. The output is adjustable from -1.3V to -12V. Negatron is also able to step up/step down the magnitude of the voltage. For example, you can feed Negatron +9V and it can give you a -5V or a -12V rail.
Negatron is the perfect choice for engineers frustrated with trying to create a negative voltage source in their low power circuit.
Negatron will operate from a 4V to 14V input and the output voltage is set with the small screw potentiometer on the top.
Negatron is pin-compatible with the common 78XX series of linear voltage regulators, so it will work with breadboards and other popular prototyping methods.
Negatron is very different from any other DC-DC converter on the market so please read the entire datasheet thoroughly before buying or using one.
Performance:
-1.3V to -12V output voltage range
4V to 14V input voltage range
0.5A max output current @ -5V when powered from +9V
0.25A max output current @ -12V when powered from +12V
(please see datasheet for current ratings at other input/output voltages)
~100mV typical ripple
External components not normally needed
Protective features:
Overcurrent protection
Thermal protection
Datasheet:
Negatron.pdf (182kb)
