Hello

On 31.08.12 23:18 , gafbf wrote

> In the gear is just written 12v DC, I've try one power supply with 100 ampere, and it seem that it is not enough.

12V with 100 Ampere is enough to start a diesel trucks engine ;-)

I assume you mean Milliampere (100mA): yes, that is not enough. The
specs say 300mA. But my experience is: if you use modern wallwart
powersupply a 500mA is more reliable.

Explanation: the heavy old wallwarts contained a transformer based
supply with large capacitors, which could catch spikes in the
consumption quite well. The modern light weight wall warts use a so
called switching powersupply, which do not have those large capacitor
anylonger. So they cannot catch those spikes. If the supply is a little
over dimensioned, a short breakdown does not reach "deep" enough to
disturb the 707

Florian