Surge protection in DC input

We at Röcklinger are very happy to share construction and design tips for you out there who are exploring the wonderful world of sound perfection and creating your own circuits. 

In order to protect against surge in DC inputs, bidirectional diodes such as the SM15T39CA from Microelectronics for instance, are very often used. The location of these diodes define the characteristics that the input circuit will have. If you place the diode fore the common-mode choke coil the diode and fuse will break when you put a disturbance in the DC input. Instead, place the diode after common-mode choke and you get a resistor in series with the diode thus limiting the inrush current.